university of pretoria · in food safety, biological control of fruit diseases and post harvest...

1 Jaarverslag / Annual Report 2003

University of Pretoria CONTENTS (click on headings for text)

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Annual Report 2003�


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� The year 2003 has come to its end and we can reflect on a year of extraordinary achievement in the department. The 31 Scientific publications reflect the quality of research and training and I would like to give a brief overview of the activities. Professor Nel uses gene manipulation technology in the study of aspects of gene expression and protein function in a variety of microorganisms, including a number of important viruses. He also implements molecular genetic analysis in the diagnostics and taxonomy of various important groups of viruses, bacteria and fungi. Professor Korsten’s research field is in food safety, biological control of fruit diseases and post harvest pathology of citrus and subtropical crops. There are two

other academic staff members in the Division for Microbiology. Professor Jacques Theron’s research focuses largely on bacterial biofilms with a view to biotechnological applications. His other research interests focus on the structure-function relationships of orbivirus encoded gene products and has projects with the aim of developing effective new generation recombinant vaccines against viral diseases of animals. Dr. Fanus Venter’s research focuses largely on environmental microbiology with a special interest in molecular epidemiology. He focuses on the development and application of techniques for the detection and typing of pathogens (bacteria and protozoan parasites) in water. He has also been involved in the design of water quality monitoring systems. During the course of 2003, two academic staff members in this division resigned. Professor Volker Brözel left South Africa to take up a position in the USA and Dr. Julian Jafta joined the National Department of Agriculture. The associate professorship and senior lecturer posts are in the process of being filled. There are four academic staff members in the Division for Plant Pathology. Professor Teresa Coutinho’s research focuses on pathogens of trees particularly those caused by bacteria. In this regard she is interested in taxonomy and epidemiology of this group of important plant pathogens. Professor Terry Aveling is involved in studying the pathogens of southern African indigenous food crops. Her group concentrates on those crops grown by small scale farmers in areas of low agricultural potential. To date most research has been done on diseases of cowpeas, which is a drought resistant crop that grows well on poor soils, and on bambara groundnuts. Mycotoxin studies and identification of storage fungi of cowpeas is also underway. Professor Nico Labuschagne main research focus is on Integrated Plant Disease Management. This research encompasses both biological and chemical control of fungal pathogens as well as plant parasitic nematodes. He also has a research interest on root/soilborne diseases. Lastly, Dr. Altus Viljoen manages a research programme on banana disease and pest control, banana microbial phylogenetics, banana functional genomics and banana tissue culture. Roughly divided into two areas, the programme consists of integrated disease and pest management and banana biotechnology.

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Doserende personeel / Lecturing staff Prof Cloete TE: MSc(UOVS) DSc(Pret) Pri Sci Nat – Professor and Head

Prof Coutinho TA: BSc, BSc Hons, MSc, PhD (Natal) – Associate Professor

Prof Korsten L: BSc(Hons)(Stell), MSc PhD(Pret) - Professor

Prof Nel LH: MSc(UOVS), PhD(Pret) - Professor

Prof Steyn PL: MSc(Agric)(Pret) PhD(Calif) Pri Sci Nat - Adjunct Professor

Prof Aveling TAS: MSc PhD(Natal) - Associate Professor

Prof Wingfield MJ: BSc(Hons)(Natal) MSc(Stell) PhD(Minnesota) – Professor and Director: FABI

Prof Theron J: BSc BSc(Hons) MSc PhD(Pret) – Associate Professor

Dr Labuschagne N: MSc(Agric) DSc(Agric)(Pret) Pri Sci Nat - Snr Lecturer

Dr Venter SN: MSc(Pret) PhD (Pret) Snr - Lecturer

Dr Viljoen A: BSc, BSc (Hons) PhD (UOVS) – Snr Lecturer

Technical assistants Ms Kerien van Dyk: MSc, UP

Ms Wanda Markotter: MSc, UP

Mrs Aida Bosch: Diploma in Medical Technology

Mrs Amelita Lombard: BSc (Agric Hons), UP

Mrs Mariette Truter: BSc (Hons) UP

Support Staff Mrs Madelein Botha (Secretary) Mrs Bettie van Rooyen (Secretary) Mrs Lilian Motale Mr Albert Molefe

Industry Funded Staff (Citrus and Subtropical) Ms A Redmond: Research Assistant Ms T Beart: Technical Assistant

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Ms D Muller: Administrative assistant

Departmental Staff Members: Front: Prof J Theron, Mrs M Truter, Prof T E Cloete (Head of Department), Me K van Dyk, Mrs A Bosch.

Back row from left: Prof N Labuschagne, Me W Markotter, Prof T Couthino, Prof L H Nel, Prof L Korsten, Mrs A Lombard, and Mrs M J Botha

Final Year Class of 2003 who decided to continue with their honours degrees in the department.

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Gevers, Tanja

Du Plooy, Heinrich

Harmzen, Gerda

Dawlal, Pranitha Botha, Liz

Kotze, Aletta


Jooste, Donovan

Jooste, Lucinda

Mehl, James Mohammed-Ali, Asha Labuschagne, Christo

Kvas, Maria

Naidoo, Mershann Muncro, Claire Ooshuyen, Wihelm

Stewart, Katherine Willemse, Mulda Winterton, Claire


MSc-Students

Asare, F Auret, EE B. Buthelezi Bandounas, T Bankoes, C Begashaw, LM Bohmer, B Burger, L Burke, LM Chabalala, HP Chale-Matsau, B Chandran, M Cooper, C De Jager, ES Demoz, B

Dilima, N Domola, MJ Du Plessis, DJF Du Plooy, GW Du Preez, M Fourie, A Gantsho, N Gouws, R Govender, V Grimbeek, E Groenewald,S Gull, C Gumbo, J Havenga, W Hlupheka, P

Hunter, GC Juckers, E Khalata, M Kola, ME Le Roux WJ Lindeque, M Louw, K Mashau, F Masoabi, T D Matlala, AK Mavhungu, J Mienie, NJJ Millard, CP Mnisi, S Motshane,L Mphahlele, M

Mphalele, MP Nakabonge, G Ndunguru, J Nel, B Nemato, H Nyoni, T Olajubo, R Opperman, M Orlay, Phaswana, Y Pieterse, N Posthimus, C Pretorius, M Ramokolo, LAJ Roos, HJ Schoeman, MV

Silimela, M Smith, JJ Sorril, M Storey, P Surridge, K Swartbooi, MJ Tosago, P Truter, M Tshabalala, B Uaciquete, A Uaciquete, A Van Schalkwyk, A Van Zyl, R Verwey, F Wolmarans, B Wolmarans, B


PhD-Students

Adandonon, A Boshoff, M Britz, H Coetser, SE Dube, R Hawumba, JF

Hugues, B Jacobs, A Kappindu, S Kock, MM Kritzinger, Q Kwerepe, BC

Le Grange, C Maseko, B McDonald, R Obagwu, J Pakela, YP Said, M

Severn-Ellis, A Slippers, B Smith, JE Steyn, B Thantsha, M Thompson, AH

Van den Berg, N Van der Linde, EJ Van der Waals, JE Visser, M Weldern,G Weyers, JB

Prof L H Nel was awarded an exceptional achievers award by the University of Pretoria. This award was given in recognition for his excellence in undergraduate and postgraduate teaching, scientific research and status and administrative contributions. No less than 17 students have been awarded their MSc and/or PhD research degrees with him as the promoter over the past three years. In this period one postdoctoral student also completed his fellowship with considerable success.

Since the year 2001, Prof Nel has published 21 papers in Science Citation Indexed Journals and /or chapters in books and he also enjoys considerable international recognition. This is evident from the

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favourable evaluations and recognition by all the major international players in his field – that include amongst others:

• Director, World Health Organization Collaborating Center for Reference and Research on Rabies, CDC, Atlanta, USA.

• The Director for Lyssavirus research, Pasteur Insititute, Paris, France. • The Head, Rabies Centre of Expertise, Government of Canada. • Head of Rabies, Virology Dept, VLA – Weybridge, Surrey United Kingdom. Prof Nel furthermore regularly acts as critic for leading journals and as referee for local and international project proposals (most recently for the Department for Environment, Food and Rural Affairs, UK (DEFRA, London), and as session chair at local and international meetings. Prof Nel is consulted throughout southern Africa and the larger continent as a leading expert on Lyssavirus research. He has also made significant contributions to working groups of the Government and to international working groups, including those of the IAEA and the FAO (UN). His international standing is also reflected by the following official roles and invitations ie:

• 2000: Emerging infectious diseases international fellowship: Comparative evaluation of scientific status/merit by an international panel of experts. Received this prestigious award from the association of public health laboratories (USA).

• 2002 and ongoing: Scientific advisor to the South and East African Rabies Group made up of 18 African countries and representatives from the USA, Canada, UK, France, Germany and Thailand.

• 2002: Organizer of the first Biotechnology in Agriculture conference of the Molecular and Cellular Biology Group, in Pretoria.

• 2002 and 2003: Co-organizer and one of the principal presenters of two international workshops on the use of molecular technology in disease diagnostics for the International Atomic Energy Agency (IAEA) and the Food and Agriculture Organisation of the United Nations (FAO).

• 2003: Organizer of the 7th International SEARG conference in Swaziland and election to the SEARG Executive Board.

• 2003: Invited to represent the African continent and deliver a key note address “Lyssaviruses isolated on the African continent”; Centennial celebration of the Pasteur Institute, Sao Paulo, Brazil.

• 2003: Member of the National DST Roadmapping Committee: Biotechnology in Animal Health.

• 2003: Invited to deliver a key note address, “Problems inherent to the presence of rabies on the African continent”, at the opening global rabies session of the 2003 Rabies in the America meeting; Thomas Jefferson University in Philadelphia and the Wistar Institute, Philadelphia, Pennsylvania, USA.

• 2003: Nominated as member of the World Health Organization (WHO) global lyssavirus taskgroup


As the head of the Microbiology division, Prof Nel has for a long time played an important administrative, managerial and planning role within the Department. He has recently also acted a Head of the Department for a six month period, and performed this function with excellence. Within the larger University context Prof Nel has played various important roles in the past years and currently serves on the Faculty Postgraduate Committee as well as the Faculty Appointments Selection Committee. I am of opinion that he fulfills these roles with distinction. This award is well deserved and we congratulate Prof Nel and wishes him the very best with his continued contributions to the success of our Department.

Promotion – Prof N Labuschagne Nico Labuschagne has recently been promoted to associate professor in the department of Microbiology and Plant Pathology. He was born in Springs, South Africa, attended Die Poort primary school outside Pretoria and matriculated at F.H. Odendaal high school. Nico enrolled for a BSc(Agric) degree in Microbiology at the University of Pretoria, and later switched to Plant Pathology. He completed his BSc (Agric) degree in 1979. During 1980 he joined the Oil Seed Research Group (Potchefstroom) in the Department of Agriculture and Fisheries and was seconded to do an Honours degree in Plant Pathology which he completed in 1981. He subsequently joined Agricura (Agrihold) as a research Plant Pathologist. During 1982 he joined the University of Pretoria as a lecturer in Plant Pathology. He completed his Masters degree cum laude during 1983 on the topic of Thielaviopsis basicola (Chalara elegans) as a pathogen on groundnut. In 1984 he was promoted to senior lecturer. Continuing in the field of soilborne diseases he completed his DSc on the topic of Fusarium solani associated with citrus root disease during 1988. Currently Prof Labuschagne is lecturing in Disease control, Introductory Crop Protection and Nursery & Seed Pathology. Prof Labuschagne has maintained, as his main research focus, soilborne diseases, with emphasis on etiology and control including chemical and biological control and resistance mechanisms. His research involved mostly fungal diseases, but also included nematode diseases of citrus, bambara groundnut, yam and bananas. Some of the highlights of his research include evidence of a link between the citrus blight syndrome and naphthazarin toxins produced by F. solani. Another break-through has been elucidation of the biochemical mechanisms involved in citrus rootstock resistance against Phytophthora nicotianae. More recently he initiated a research program on control of root diseases in hydroponic systems and developed an Integrated Disease Management System for hydroponics in South Africa. Another research program which was recently started involves biological control of plant diseases with Growth-Promoting Rhizobacteria. Prof Labuschagne has been promotor or co-promotor of 10 masters and two PhD students and has been author or co-author of 40 publications in scientific journals and international conference proceedings. He is currently supervisor for four PhD and six MSc students.

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Promotion – Prof T.A. Coutinho

Prof Teresa Coutinho was recently promoted to full professor in the Department of Microbiology and Plant Pathology. She was born in Welkom on 30 July 1961 and attended Selly Park Convent in Rustenburg. She completed her BSc and BSc Hons. degrees at the University of Natal, Pietermaritzburg, majoring in Plant Pathology. She was awarded her MSc from the same University in 1988 under the guidance of Prof. M. Wallis. The topic of her research was the characterisation of a previously undescribed bacterial disease of maize. In 1991 she was awarded her PhD which she completed under the guidance of Prof. F.H.J. Rijkenberg at the University of Natal.

Her studies were on the economically important leaf rust disease of coffee. Her research focused on the infection biology of the causal agent, Hemileia vastatrix, in both susceptible and resistant hosts. In 1994, Teresa was appointed as a lecturer in Microbiology at the University of the Free State. In 1998, she took up a position as a senior lecturer in the Department of Microbiology and Plant Pathology at the University of Pretoria and was promoted to associate professor in 2000. Since 1994, her research has focused on pathogens of tree crops, particularly forest tree species. Much of her research has been in the broad field of taxonomy where she has been involved in characterising both fungal and bacterial pathogens. These have included Fusarium circinatum, the fungus responsible for pitch canker of pines, and Pantoea spp. associated with bacterial blight and dieback of eucalypts. She is a team member of the Tree Pathology Co-operative Programme (TPCP) and, in this regard, is responsible for disease diagnosis.

Recently, Eugene Cloete, a professor at the University of Pretoria’s Natural and Agricultural Sciences faculty and Chairperson of the School of Biological Sciences as well as Head of the Department for Microbiology and Plant Pathology, was elected Vice-president of the International Water Association (IWA) at an IWA board meeting held in Japan during the 3rd World Water Forum in OSAKA and Kyoto. Cloete is an outstanding researcher and expert in water supply and sanitation as well as industrial and wastewater treatment and has published extensively in these fields with more than 90 publications in Science Citation Indexed journals and holds six patents.

He has been a member of the IWA Governing Board for the past two years and was elected to the

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IWA Strategic Council during 2002. Cloete previously served on the Management and Policy Council for a number of years and is currently the chairman of the IWA Specialist Group on Bio-fouling and Bio-corrosion. Among his impressive accomplishments, his contribution to water issues lies in the practical implementation of his research, including the development of a solar water pasteurisation system for producing potable water in rural areas, a better understanding of biological phosphorus removal from activated sludge and the optimisation of the chemical control of bio-fouling and bio-corrosion and the development of processes for treating acid mine drainage, in collaboration with the private sector and industry.

Prof Cloete teaches Microbiology at the undergraduate as well as the postgraduate level. He introduced a coursework masters degree in Water resource management and since its inception three years ago, 30 MSc students have completed their degrees. These students are employed in both the private and public sector and in their own right, are making major contributions to water management in South Africa. He also runs the Centre for Water Biotechnology and more than 45 students have completed their MSc and PhD degrees, with him as promoter, in this program during the past ten years. No less than eight of these students are currently professors and or lecturers at South African Universities and many of the others play a leading role in their organisations.

He recently completed a project in collaboration with the Netherlands in the SANPAD program, where the status of rural water supply in South Africa was determined. The results from this research, has lead to a heightened awareness, and the need to supply potable water in rural areas in order to prevent disease, both with government and also in the areas affected. He is currently involved in a project addressing the cholera epidemic in rural South Africa. Apart from the epidemiology and causative factors, ways are being provided to counteract the disease. In this regard he is steering a project initiated by the TUK’s RAG committee to bring safe water, using solar pasteurisation, to a rural area in the Eastern Cape. This project is being extended by means of the commercialisation of the solar pasteurisation technology which he developed in collaboration with Business Enterprises at UP. IWA is the largest global network of water professionals, spanning the continuum between research and practice and covering all facets of water. One of its aims is to advance education in particular by the exchange of information and experience, and promotion of research into the scientific, biological, engineering, legal and administrative aspects of water pollution abatement and control and in the publication of the results of this research for the benefit of the public.

Through IWA, more than 6000 members collaborate to lead the development of effective and sustainable approaches to water management, with emphasis on the science and management of drinking water, wastewater, storm-water and the conservation of water resources throughout the world. IWA seeks to create value and drive the advancement of both the science and best practice of water management in cooperation with other similar international efforts in the fields of water resources, and irrigation and drainage.

The ultimate strength and potential of IWA lies in the professional and geographic diversity of its membership represented by 52 Specialist Groups consisting of a “mosaic” of member communities including academic researchers and research centres, utilities, consultants, regulators, industrial water users and water equipment manufacturers and spanning more than 120 countries.

IWA members from each of these stakeholders represent the leading edge in their fields of specialty, and together are building new frontiers in global water management through interdisciplinary exchange and collaboration. It joins the network of initiatives of the past decade, of the Stockholm Water Symposia, the World Water Forum, the Global Water Partnership, UNEP, UNESCO and the


World Health Organisation. IWA and its members are committed to furthering sustainable and holistic resource management and service provision, built on the concept of the complete water cycle.

• Dr W Hammond, Biological Control Center for Africa, International Institute of Tropical Agriculture, Benin

• Prof J van Buuren, Wageningen Agricultural University, The Netherlands • Dr J Legg, International Institute of Tropical Agriculture, Uganda • Prof Shin-Chuan Hwang, Taiwan Banana Research Institute, Taiwan • Dr G Thompson, Agricultural Research Council (ARC), South Africa • Dr A Majewska, University of Medical Sciencies in Poznan, Poland • Dr Christiaan Steinberg, INRA, Dijon, France • Dr Jean-Vincent Escalant, INIBAP, Montpellier, France • Karine Dr�nen, Bergen University, Norway • Lise Øvereås, Bergen University, Norway • Frida Lise Daae, Bergen University, Norway

• Prof P Ashton, CSIR, Environmentek, South Africa

• Prof R M Atlas, University of Louisville, Kentucky, USA

• Prof P L Steyn, Pretoria, South Africa

• Prof B Strydom, Pretoria, South Africa

• Prof H Kasan, Randwater, Johannesburg, South Africa

• Prof P Jooste, Pretoria, South Africa

• Prof G Viljoen, Onderstepoort Veterinary Institute, South Africa

• Prof Wally Marasas, Medical Research Council, Tygerberg, South Africa

• Prof Pedro Crous, CBS, Utrecht, The Netherlands

• Prof G Pietersen,

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1. Prof T E Cloete was invited as a keynote speaker at the Third World Water Forum, Osaka,

Japan, 2003. 2. Prof T E Cloete was visited to the University of Bergen on a Collaborative research

programme. 3. Prof T E Cloete was invited as a guest as formal representative of IWA as Vice-President to

the IWA Biosolids Conference in Trondheim, Norway June 2003. 4. Prof T E Cloete attended the IWA Strategic council and Board Meetings as Vice-president.

Prague, September 2003. 5. Dr A Viljoen visited Mozambique on a Research visit to collect Sigatoka leaf disease samples

of banana. 8-10 April. 6. Dr A Viljoen visited Ethiopia on a Research visit for enset diseases. 21-28 Julie. 7. Dr A Viljoen visit Brazil for the International Workshop on Fusarium wilt of banana,

Salvador, Brazil. 22-26 September. 8. Susan Groenewald and Barbara Nel (MSc students of Dr A Viljoen) visited Brazil for the

International Workshop on Fusarium wilt of banana, Salvador, Brazil. 22-26 September. 9. Gizachew Weldemichael (PhD Students of Dr A Vijoen) visited Ethiopia for Research enset

diseases. 2 July – 12 August 10. Dr Retha Slabbert (Post-doc) visited France at CIRAD for training in banana cell

suspensions. 30 June – 4 July 11. Prof Korsten visited Dole Laboratories Hamburg in April. 12. Prof Korsten, Zelda Pieterse and Willeke Keesenberg visited European markets to trace the

quality of South African export fruit in July 2003. 13. Prof Korsten attended the 4th Official Eurepgap Conference in Madrid, Spain.

Sabbatical – T.A. Coutinho

I spent three months, from the 2nd of September to the 28th November 2003, in the Laboratorium voor Microbiologie, University of Ghent, Belgium. My host was the eminent microbial ecologist and bacterial taxonomist, Professor Jean Swings. The objective of my research was two-fold. Firstly, I attempted to identify and characterise Pantoea spp. infecting eucalypts locally and countries where symptoms similar to those observed in South Africa have been reported. Preliminary results suggested that more than one member of the Enterobacteriaceae are involved in this disease. Secondly, I attempted to identify and characterise two species of Pantoea associated with Coniothyrium canker of eucalypts in South Africa. These two bacterial species are believed to have a synergistic interaction with the fungal pathogen, Coniothyrium zuluense.

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During the course of the past two years, we have obtained authentic Pantoea ananatis strains from a number of hosts including rice, onions, pineapple, sudan grass, melons and a clinical strain. These strains were included in this study together with strains isolated from eucalypts showing typical symptoms of bacterial blight and die-back from various countries in South America and Uganda. Preliminary results obtained in South Africa indicated that we were dealing with P. ananatis and one or more unknown Pantoea spp. After examining the results obtained in South Africa, it was decided that my first research objective in Gent would be to try and group the strains using another molecular method, namely, REP-PCR. Included in this study, were the eight Pantoea type species. It was also decided to include two authentic strains of each of these species to determine the variation in profiles within a species. A computer programme, Bionumerics, was used to analyse the results obtained. It was decided to only consider the results obtained from the ERIC profiles because they were more distinct than those obtained using BOX primers. All 68 strains used in this study, including the eight found associated with Coniothryium zuluense, grouped into 5 clades. The type strain of P. ananatis grouped with the largest clade. The type strain of P. agglomerans also grouped with one of the clades. All other types strains were distinct and grouped separately. These results were then compared to those obtained in South Africa and the strains grouped accordingly. The next step was to conduct DNA:DNA hybridisations between selected strains from the various sub-clades and the type strains of Pantoea. This is a complex process which requires DNA of a very high quality and quantity. The first task was to grow up sufficient quantities of bacteria for DNA extraction (i.e. at least 1 gram). Because of the time constraint it was decided that three strains from Uganda, eight strains from South America and eight strains associated with C. zuluense would be hybridised with the type strain of P. ananatis. Hybridisation with the other type strains would proceed once we ascertained which strains were indeed P. ananatis. The hybridisation method, which is very sensitive and requires very careful preparation, is based on fluorometric measurements. Microdilution well plates are used so each hybridisation is repeated four times and results averaged and analysed statistically. None of the strains obtained from Uganda and South America are P. ananatis (DNA binding values range from 4 – 56%). Three of the eight strains associated with C. zuluense are P. ananatis (DNA binding values range from 74 – 94%; others had a values between 39 – 56%). Based on these results, DNA from two strains from Uganda and two strains associated with C. zuluense but not P. ananatis were hybridised with DNA from the types of P. agglomerans and P. stewartii subsp. indologenes (based on 16S rRNA gene sequences these two species are closely related to P. ananatis). None of these strains are either P. agglomerans or P. stewartii subsp. indologenes and are thus probably undescribed Pantoea spp.

My first impression of the Laboratorium voor Microbiologie was of vibrancy. The atmosphere was very similar to FABI and I felt at home. Academics, students and technicians in the Laboratorium conduct focused research in the broad field of bacteriology. They also have a commercial bacterial culture collection and a diagnostic service available. The topics they cover in the field of bacteriology are broad – from probiotics to identifying lactic acid bacteria found in cheese. The group consists of 60 people, a third are academics and researchers, a third students and a third are

Prof. Jean Swings who is the head of the Laboratorium voor Microbiologie at the University of Gent and he was Prof

Couthino host.


technicians linked to the BCCM/LMG collection. I shared a laboratory with a visiting Serbian professor working on lactic acid bacteria and Dr. Marc Vancanneyt, a researcher and my “hands on” collaborator on this project. I thoroughly enjoyed doing hands-on research again and by re-examining my daily programme perhaps I can spend more time in the laboratory in future. Having no responsibilities other than getting results was pleasurable. Gaining some experience in molecular techniques has boosted my confidence. I have now learnt how to do techniques I had previously only had an understanding of – REP-PCR and DNA:DNA hybridisations. I was also given opportunities to see other bacterial diagnostic techniques performed. These included FAMES, SDS-PAGE and DGGE.

While at the University of Ghent, I attended the PhD defences of two candidates from the Laboratorium voor Microbiologie. I was fortunate to meet with the gurus of bacterial taxonomy who were the external examiners of the two candidates. A “Feest” was held for Professor Monik Gillis to celebrate her retirement from the Laboratorium. It was in the form of a mini-symposium with invited speakers. I was invited to present two seminars one entitled: “Coniothyrium canker of eucalypts: a phytopathological enigma” at the Centraal Bureau voor Schimmel cultures (CBS) in Utrecht, the Netherlands on the 5th of November 2003 and the other entitled: “South Africa, Forestry and Pathogens” in the Laboratorium on the 26 November 2003.

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� � �� The Water Biotechnology Group focused their research on the passive treatment of acid mine drainage, microbial community diversity studies in activated sludge, and on solar pasteurisation of water supplies in rural areas. A new dimension was added with the three PhD students in Water Resource Management focusing on a multi-criteria decision making model for integrated catchment management in the one instance, a national strategy for monitoring the microbial quality of water supplies in the other and the third project revolving around the development of a national strategy for water supply in rural areas. Significant advances have been made in the development of a passive treatment system for acid mine drainage. The group working on activated sludge population dynamics, indicated for the first time, that the exopolymers produced by bacteria in activated sludge contained phosphorus and could play a major role in biological phosphorus removal from waste water. Research on solar pasteurisation indicated that this technique could be used successfully for treating groundwater to meet potable standards, hence providing an ideal cost effective method for treating contaminated water in rural areas. Biofilm physiology: The bulk of bacteria occuring in the environment grow at surfaces, forming biofilms. Bacteria growing in biofilms display a unique phenotype distinct from broth or agar

RESEARCH PROJECTS


cultured cells. The behaviour of Pseudomonas aeruginosa and Bacillus cereus in biofilms is under investigation by proteomic (2D electrophoretorgrams of proteins), as well as genetic analysis. The regulation and function of a number of regulatory elements of P. aeruginosa affected during growth as a biofilm are being studied. The growth, activity and survival of pathogenic bacteria in drinking water biofilms is also under investigation. Bacterial pathogens in water: The research focus entails the development of detection and identification methods, as well as a study of the fate (survival) of water-borne pathogens. Detection, typing and identification methods for Vibrio cholerae in surface and drinking water sources are developed. The prevalence of bacterial pathogens in biofilms associated with drinking water is investigated, as is the survival of pathogens in fresh water sediments. Environmental biotechnology: The use of micro-organisms to inhibit pollution is researched. Emphasis is placed on water pollution with special reference to waste water, industrial waste water, industrial effluent cooling water and water supply.

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Forest Pathology: New tools have been developed to understand population diversity of some key pathogens of plantation trees in South Africa. This will significantly enhance our ability to deal with losses due to associated, and often serious losses. In addition, new knowledge has been gained on the biology of important insect pests and diseases. Furthermore, new pathogens have been discovered and techniques to identify them have been explored.

Citrus black spot research Citrus black spot (CBS), caused by Guignardia citricarpa Kiely, has become an important disease in global fruit trade, due to phytosanitary restrictions. The pathogen attacks both leaves and fruit, resulting in cosmetic lesions on the latter, which can result in rejection of fruit destined for export. Our research mainly focuses on basic epidemiological studies (infection conditions, growth requirements, sporulation, etc.) and disease control. It is important to work in close co-operation with the producers to ensure that the control strategies are practical and economical viable.

White rust of Sunflower: White rust is considered the most damaging sunflower disease in South Africa, and is caused by the obligate parasite Albugo tragopogonis. Research on the disease is difficult, since no greenhouse inoculation techniques are available. The development of such a technique will assist in the study of control methods which will include chemical control.

Panama disease of bananas:


Panama disease is considered to be one of the most damaging plant diseases in the world. In South Africa, the disease is particularly severe in the Kiepersol and Southern KwaZulu-Natal area. Since no effective method of control is available, an integrated disease management program to limit the effect of the disease in the field is being developed. This programme integrates plant disease resistance, biological control, general plant health and disease management. The pathogen population was been analysed and the spread of the fungus determined. Postharvest Pathology Pre and postharvest factory that influence postharvest quality of fruits and vegetables are studied to ensure sustained market access through quality assurance. Postharvest pathogens that infect fruits and vegetables pre or postharvestly are studied in terms of ecology, biology and control.

Integrated disease management: Alternative disease control strategies as part of integrated disease management systems focus on the use of biological and other natural control options. The reduced use of agrochemicals coupled with more environmentally friendly ways to control diseases and enhance plant growth, forms an integral part of IDM systems.

Hydroponic pathology: The main focus is the etiology and control of Pythium wilt and root rot in hydroponic systems. A disease control strategy is being developed for the different types of systems. A range of Pythium isolates have been isolated from the main hydroponic crops. These isolates are now being identified and screened for pathogenicity.

Nitrogen Fixation: Leguminnous plants and their rhizobial symbionts are investigated to increase the application of Biological Nitrogen Fixation in South African agriculture. Rhizobia from a wide range of plant hosts are characterised in an effort to determine the diversity of the bacterial symbionts and possibly identify inoculant species for agricultural application.

Biochemical aspects of the quality and health properties of tea: DNA primers are used to identify tea cultivars of different qualities, and the role of polyphenols in conferring quality and health aspects on tea is investigated.

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Biocontrol of plant diseases: Development of natural disease control products such as natural plant extracts and microorganisms that can control the most important plant diseases on a commercial scale. Phytobacteriology Pantoea ananatis is the casual agent of serious diseases on a number of monocotyledous and dicotyledous plant species worldwide. In South Africa, this bacterial pathogen causes large-scale losses to the forestry industry where it infects young eucalypt trees. The blight and die-back caused by P.ananatis either causes tree death or the production of multi-stemmed plants, and undesirable silvicultural trait. Similar symptoms have also


been reported from other countries, but the causal agent involved has not been identified. Due to the serious nature of the disease, a research programme was initiated by the Department to understand the biology and ecology of P. ananatis. One problem that repeatedly confronts the group is the difficulty to accurately identify the bacterium because of its similarity to other Pantoea species. This problem led to a collaborative project between our group and experts on Pantoea identification at the University of Ghent in Belgium. Soilborne diseases: Biochemical resistance mechanisms against soilborne pathogens are being investigated in citrus rootstocks. The yam nematode is being studied pertaining to aspects such as pathogenicity, genetic variability and rapid resistance screening.

Citrus and Subtropical research The most important diseases of citrus and mango are studied and include citrus greening, blackspot and root rot. Mango research focus mainly on treeding back, black spot anthracnose and soft brown rot.

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Molecular biology and virology: Gene manipulation technology is used in the study of aspects of gene expression and protein function in a variety of micro-organisms, including a number of important viruses. Molecular genetic analysis is also implemented in the diagnostics and taxonomy of various important groups of viruses, bacteria and fungi.

��

1. CLOETE, T.E., WESTAARD, D., and VAN VUUREN, S.J. 2003. Dynamic response of biofilm to pipe surface and fluid velocity. Water Science & Technology. 47(5): 57–59

2. CLOETE, T.E. 2003. Biofouling control in industrial water systems: What we know and what we need to know. Materials and Corrosion. 54: 1-7

3. CLOETE, T.E. 2003. Resistance mechanisms of bacteria to antimicrobial compounds. International Biodeterioration and Biodegradation, (51) 277-282

4. THERON, J. and CLOETE, T.E. 2003. Applications of Molecular Technologies in Environmental Biotechnology for Monitoring Bacteria, Bioremediation. 8: 205-231

5. THERON, J. and CLOETE, T.E. 2003. The microbiology of biological phosphorus removal using activated slude. Journal of Environmental Engineering and Science. 4:273-280

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20. VAN DER WAALS, J.E., KORSTEN, L., AVELING, T.A.S. AND DENNER, F.D.N., 2003. Influence of environmental factors on field concentrations of Alternaria solani conidia above a South African potato crop. Phytoparasitica, 31(4):353-364.

21. VAN DER WAALS, J.E., KORSTEN, L., VAN RIJ, N. & DENNER, F.D.N. 2003. Evaluation of PLANT-Plus, a decision support system for control of early blight on potatoes in South Africa. Crop Protection 22:821-828.

22. SANDERS, G.M. & KORSTEN, L. 2003. A comparative morphological study of South African avocado and mango isolates of Colletotrichum gloeosporioides. Canadian Journal of Botany 81(8):877-885.

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�� 1. Surridge, A.K.J., Viljoen, A., and Wehner, F. 2003:

Fungi associated with banana foliage in South Africa. Pages 95-98 in: Mycosphaerella leaf spot diseases of bananas: present statu s and outlook (ed. Jacome, L., Lepoivre, P., Marin, D., Oritz, R., Romero, R, and Escalant, J.V.). Proceedings of the Workshop on Mycosphaerella leaf spot diseases held in San Jose, Costa Rica on 20-23 May 2002. INIBAP, Montpellier, France.

2. Viljoen, A., Surridge, A.K.J., and Crous, P.W. 2003: The impact of minor Mycosphaerella spp. on banana in South Africa. Pages 61-66 in: Mycosphaerella leaf spot diseases of bananas: present status and outlook (ed. Jacome, L., Lepoivre, P., Marin, D., Oritz, R., Romero, R, and Escalant, J.V.). Proceedings of the Workshop on Mycosphaerella leaf spot diseases held in San Jose, Costa Rica on 20-23 May 2002. INIBAP, Montpellier, France.

3. Kola, M.E., Avenling T.A.S., Regnier, T. & Hall, A.N. 2003: Surface topography and polyphenols of bambara groundnut seed coats. Proceedings of the

Microscopy Society of Southern Africa 33:65

4. Kritzinger, Q., Aveling, T.A.S. & Van Der Merwe, C.F. 2003: Effect of fumonisins on the ultrastructure of cowpea seed. Proceedings of the Microscopy Society of Southern Africa 33:64.

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1. THERON, J and CLOETE, T.E. 2003. Applications of Molecular technologies in

Environmental Bitechnology for Monitoring Bacteria. In: Marine Biotechnology, Volume 8 Bioremediation, Science Publishers, Inc. pp 204-231.

2. THERON, J. and CLOETE, T.E. 2003. Emerging microbiological detection techniques.

(In press) 3. CLOETE, T.E., EHLERS, M.M., VAN HEERDEN, J. and ATKINSON, B. 2003. The

microbiology of phosporus removal in activated sludge. The Handbook of Water and Wastewater Microbiology, 374-390

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6. NEL, L.H., & VILJOEN, G.J., (Authors). “PCR Methodology and Diagnostic Application for Animal Diseases (Ten Chapters) 2003. In Press, FAO Press, Vienna, Austria

1. Prof T E Cloete: Transboundary rivers, sovereignty and development: Hydropolitical drivers in the Okavango River basin. African Water Issues Research Unit (AWIRU) and Green Cross International, 2003.

2. Prof T E Cloete: Biofilm Monitoring, Water Science & Technology, IWA Publishing, 2003.

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Invited Paper

1. Korsten, L. 2003. Analysis of the accreditation status and focus of research and diagnostic laboratories in Southern Africa. Test and Measurement Conference. Birchwood Conference Centre, 25-27 August 2003. Invited paper.

Papers 1. Kritzinger, Q., Aveling, T.A.S., Marasas, W.F.O., Rheeder, J.P., Van Der Westhuizen,

L. and Shephard, G.S. 2003. Mycoflora and fumonisin mycotoxins associated with cowpea (Vigna unguiculata (L.) Walp) seeds. 41st Congress of the Southern African Society for Plant Pathology, 19 - 22 January, Baines Game Lodge, Bloemfontein.

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2. Paul, I., Van Jaarsveld, A.S., Erasmus, B.F.N. & Korsten, L. 2003. Climate change and the potential distribution of Guignardia citricarpa Kiely, the causal agent of citrus black spot. National Symposium on Global Change and Regional Sustainability in South Africa. Kirstenbosch, Cape Town 27-29 October 2003.

3. Du Plooy, W., Prinsloo, L., Van der Merwe, C. & Korsten, L. 2003. Spatial identification

(using SEM) and characterization (using Raman & FTIR) of mango epicuticular wax. MSSA Congress, 1-5 December, Cape Town.

4. Du Plooy, W., Van der Merwe, C. & Korsten, L. 2003. Ontogeny and surface morphology

of mango fruit wax. MSSA Congress, 1-5 December, Cape Town. Posters

1. Stronkhorst, L.D., Viljoen, A., Claassens, A.S., Nel, B., & Van der Waals, J.H. 2003. The effect of N-fertilization and pH on the incidence of Fusarium Wilt (Panama disease) of banana in greenhouse trials. Golden Jubilee Congress (Soil Science Society of South Africa, South African Society of Crop Production, Southern African Society for Horticultural Sciences), Stellenbosch, 20-23 January 2003.

2. Van den Berg, N., Birch, P., Viljoen, A., Wingfield, M.J., and Berger, D.K. 2003. The identification of genes associated with tolerance/resistance to Fusarium oxysporum f.sp. cubense in Cavendish bananas. SAAB National Conference, Pretoria, South Africa.

3. Du Plesis, D.J.F., Theron, J and Brözel, V.S. The role of rhamnolipid in biofilm formation and structure of Pseudomonas aeruginosa PAO1. 18th Congress of the South African Society of Biochemistry and Molecular Biology (SASBMB), Pretoria, South Africa, 6-9 July 2003.

4. Pretorius, J.M., Brözel, V.S. and Theron, J. Identification of genes involved in Bacillus cereus biofilm formation. 18th Congress of the South African Society of Biochemistry and Molecular Biology (SASBMB), Pretoria, South Africa, 6-9 July 2003.

14. Sorrill, M., van Rensburg, H.G. and Theron, J. Development of a diagnostic assay for the

differentiation of foot-and-mouth disease infected animals from vaccinated and naïve animals for use in sub-Saharan Africa. 18th Congress of the South African Society of Biochemistry and Molecular Biology (SASBMB), Pretoria, South Africa, 6-9 July 2003.

15. Böhmer, B., van Rensburg, H.G. and Theron, J. Construction of a chimeric FMD virus

containing the determinants for antigenicity of the Saudi SAT-2 vaccine strain: a possible alternative for the current vaccine. 18th Congress of the South African Society of Biochemistry and Molecular Biology (SASBMB), Pretoria, South Africa, 6-9 July 2003.

16. Storey, P., van Rensburg, H.G. and Theron, J. Analysing the functional role of a second

RGD-triplet in a Namibian SAT-1 Foot-and-Mouth disease virus. 18th Congress of the South African Society of Biochemistry and Molecular Biology (SASBMB), Pretoria, South Africa, 6-9 July 2003.

17. Bagnall, R. C. & Labuschagne, N. 2003. Control of Pythium in hydroponic systems by

means of water treatment with sanitizers. 41ST congress of the SASPP, Univ of the Orange


Free State, Bloemfontein. January 2003. 18. De Meyer, E. & Aveling, T.A.S. 2003. Biological control of Sclerotium rolfsii on Bambara

groundnuts. 41st Congress of the Southern African Society for Plant Pathology, 19 - 22 January, BainesGame Lodge, Bloemfontein.

19. Kola, M.E., Aveling, T.A.S., Regnier, T. & Hall, A.N. 2003. Surface topography and

polyphenols of bambara groundnut seed coats. Annual conference of the Microscopy Society of Southern Africa, 2-6 December, University of Cape Town, Cape Town.

20. Kritzinger, Q., Aveling, T.A.S. & Van Der Merwe, C.F. 2003. Effect of fumonisins on the

ultrastructure of cowpea seed. Annual conference of the Microscopy Society of Southern Africa, 2-6 December, University of Cape Town, Cape Town.

21. Du Plooy, W., Vander Merwe, C., Robbertse, H. & Korsten, L. 2003. Lenticel

development related to damage of the epicuticular layers of mango fruit. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

22. Grobler, L. & Korsten, L. 2003. Propagation material of mango – playing a role in

dissemination of Botryosphaeria spp. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

23. Paul, I., Van Jaarsveld, A.S. & Korsten, L. 2003. An analysis of the suitability of

European climate for the establishment of the citrus black spot pathogen Guignardia citricarpa. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

24. Obagwu, J., Korsten, L. & Regnier, T. 2003. Testing potential biocontrol products for

control of citrus green mold under simulated export conditions. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

25. Govender, V., Korsten, L. & Regnier, T. 2003. Assessment of Bacillus licheniformis as a

biological control agent. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

26. Labuschagne, P.M., Regnier, T., Swart, G.M. & Korsten, L. 2003. Effect of temperature,

pH, flavonoids and chemicals on the germination of Phyllosticta citricarpa pycnidiospores. 41st Congress of the Southern African Society for Plant Pathology. Bain’s Game Lodge, Bloemfontein, 19-22 January 2003.

27. Regnier, T., Govender, V. & Korsten, L. 2003. Influence of wax, acid bath, chemicals and

natural products on water loss and litchi fruit quality. SA Litchi Growers’ Association Research Symposium. Tzaneen Country Lodge, 12 June 2003.


28. Venter, S.N. 2003. Food and waterborne disease and the traveller. Invited speaker at the

training course for the Diploma in Travel Medicine organised by the South African Society Of Travel Medicine, Johannesburg, 2 – 4 May 2003.

Keynote addresses 1. Cloete, T.E: Keynote address on the challenges of water supply in the developing world.

IWA session at the Third World Water Forum, Kyoto, Japan, April 2003 Invited paper 1. Korsten, L. 2003. World Bank Programme for Capacity Building on Trade, Standards and

Food Safety for Market Access and Agribusiness Development report. FAO/WHO Workshop in Collaboration with ILSI. CSIR Conference Centre, Pretoria, South Africa. 1-3 September 2003. Invited paper.

2. Venter, S.N. 2003. Salmonella in aqueous environments. Invited speaker at the Department

of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, United States of America, 21 November 2003.

Papers 1. Thosago, P. and Cloete, T.E. 2003. Quantification of phosphorus in extracellular

polymeric substances associated with the activated sludge flocs from waste water treatment systems. International Symposium on Sustainable Development, Cape Town, South Africa, 14 – 19 September 2003.

2. Louw, C.A.M., Regnier, T.S. & Korsten, L. 2003. Antimicrobial activity of bulbous plant

leaf extracts to control postharvest and foodborne diseases. Joint International Conference of the South African Association for Botanists and the International Society for Ethnopharmacology, Pretoria, South Africa. 7-11 January 2003.

3. Paul, I., van Jaarsveld, A.S. and Korsten, L. 2003. Modelling the potential geographic

distribution of Guignardia citricarpa Kiely, the causal agent of Citrus Black Spot, under changing climate. 1st Young Scientist’s Global Change Conference. Trieste, Italy, 16-21 November 2003.

4. Said M.D., Venter, S.N. and Cloete, T.E. 2003. The 2000-2002 Cholera epidemic in

KwaZulu-Natal: A possible link between population demographics, water and sanitation. Oral presentation at the IWA Specialist Conference: Water: Key to Sustainable Development in Africa Symposium, Cape Town, South Africa, 14 – 17 September 2003.

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5. J Weyer, D Wallace, G J Viljoen, L H Nel. New generation poxvirus vaccines for rabies.

7th International Southern and Eastern African Rabies Group meeting, Ezulwini, Swaziland 2003.

6. C T Sabeta, J Bingham and L H Nel. Molecular epidemiology of canid rabies in

Zimbabwe and South Africa. 75th International Southern and Eastern African Rabies Group meeting, Ezulwini, Swaziland 2003.

7. L H Nel. Invited lecture. Lyssaviruses form Africa. International Seminar on Rabies.

Instituto Pasteur Centennial, Sao Paulo, Brazil 2003. Posters 8. M. D. Said, T. E. Cloete and S. N. Venter. 2003. The 2000-2002 Cholera epidemic in

KwaZulu-Natal: A possible link between population demographics, water and sanitation. International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

9. Thantsha, M.S. and Cloete, T.E. The effect of sodium chloride and sodium bicarbonate

derived anolytes, and sodium hypochlorite on biofilms. International Symposium on Biofilms, Cape Town, South Africa, 14 – 18 September 2003.

10. Nel, B., Viljoen A, Steinberg, C. & Labuschagne, N. 2003. Evaluation of chemical

substances for the management and control of Fusarium wilt of banana. Second International Symposium on Fusarium Wilt of Banana. Salvador, Brazil 22-24 Sept 2003.

11. Aveling, T.A.S. 2003. The BCPC International Congress. Crop Science & Technology

2003. 10-12 November 2003. Glasgow, Scotland. 12. Aveling, T.A.S., Kritzinger, Q., Pakela, Y.P. & Regnier, T. 2003. Seed pathological

aspects of cowpea. 8th International Congress of Plant Pathology, 2-7 February, Christchurch, New Zealand.

13. Aveling, T.A.S. & Snyman, H.G. 2003. Effect of sewage sludge on seedling growth of

soybean in the greenhouse. Joint International Conference of the South African Association of Botanists and the International Society of Ethnopharmacology, 7-11 January, Pretoria, South Africa.

14. Kritzinger, Q., Aveling, T.A.S., Rheeder, J.P. & Van Der Westhuizen, L. 2003.

Fumonisin production in cowpea by Fusarium proliferatum. 8th International Congress of Plant Pathology, 2-7 February. Christchurch, New Zealand.

15. Kritzinger, Q., Lall, N. & Aveling, T.A.S. 2003. Antimicrobial activity of cowpea (Vigna

unguiculata (L.) Walp) leaf extracts. Joint International Conference of the South African Association of Botanists and the International Society of Ethnopharmacology, 7-11 January, Pretoria, South Africa.


16. Labuschagne, P.M., Korsten, L., Regnier, T., Sanders, G.M & Meyer, L. 2003. Effect of temperature, pH, flavonoids and chemicals on the germination of Phyllosticta citricarpa pycnidiospores. 8th International Conference of Plant Pathology. Christchurch, New Zealand.

17. Obagwu, J., Regnier, T. & Korsten, L. 2003. Control of citrus black spot with plant

extracts. 8th International Conference of Plant Pathology. Christchurch, New Zealand. 18. Sanders, G.M., Meyer, L. & Korsten, L. 2003. Application of species specific primers in

the South African citrus industry. 8th International Conference of Plant Pathology. Christchurch, New Zealand.

19. Zeeman, C.A.M., Regnier, T. & Korsten, L. 2003. Antimicrobial activity of bulbous plant

leaf extracts to control postharvest and foodborne diseases. 8th International Conference of Plant Pathology. Christchurch, New Zealand.

20. Korsten, L. 2003. Current status and future prospects of postharvest biocontrol. Biocontrol of

Postharvest Diseases Workshop, Christchurch, New Zealand. 2 February 2003. 21. Du Plooy, G.W., Van der Merwe, C.F., Robbertse, P.J. & Korsten, L. 2003. Morphology of

epicuticular layers of mango fruit. Joint International Conference of the South African Association for Botanists and the International Society for Ethnopharmacology, Pretoria, South Africa. 7-11 January 2003.

22. Regnier, T.S., Labuschagne, P.M., Swart, G.M. & Korsten, L. 2003. Toxicity of flavonoids,

natural products and chemicals to Guignardia citricarpa Kiely. Joint International Conference of the South African Association for Botanists and the International Society for Ethnopharmacology, Pretoria, South Africa. 7-11 January 2003.

23. Korsten, L. 2003. Scientific assessment of the new produce handling chapter of Eurepgap.

4th Official Eurepgap Conference “Towards Global Harmonisation 2003”. Madrid, Spain 10-12 September 2003.

24. Kgotlagomang, I., Burke, L.M., Brözel, V.S. and Venter, S.N. 2003. Salmonella enterica

subsp enterica survives in, and is readily released from, river sediments. Poster presentation at the International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

25. September, S.M., Els, F.A., Venter, S.N. and Brözel, V.S. 2003. Occurrence of non-TB

Mycobacteria in biofilms of drinking water distribution systems in South Africa. Poster presentation at the International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

26. September, S.M., Venter, S.N. and Brözel, V.S. 2003. Construction and evaluation of a

GFP labelled environmental Aeromonas hydrophila for use in biofilm studies. Poster presentation at the International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

27. le Roux, W.J., Masoabi, D., de Wet, C.M.E. and Venter, S.N. 2003. Evaluation of a rapid


polymerise chain reaction based detection technique for Vibrio cholerae isolates. Poster presentation at the International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

28. Burke, L.M., Brözel, V.S. and Venter, S.N. 2003. Construction and evaluation of GFP-

tagged Salmonella isolateds for use in survival and dissemination studies. Poster presentation at the International Symposium on Health-Related Water Microbiology, Cape Town, South Africa, 14 – 19 September 2003.

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MSc – MICROBIOLOGY Me M Thantsha

Electrochemically activated water as an environmentally safe disinfectant Abstract An increase in the number of bacteria resistant to most of the antibiotics or biocides in common use is a problem faced by industries and the community at large. More bacteria are resistant to moderate levels of biocides, with the bacteria in biofilms being the most difficult to control. High levels of

biocides are used and this has detrimental effects on the environment, as biocides are toxic to humans, being carcinogenic, corrosive and producing intolerable odours. Electrochemical activation technology provides an alternative way of controlling microorganisms. ECA water was shown in other countries to have antimicrobial properties. Anolyte, the positively charged solution is benign to fumes and corrosion caused by other biocides. Since anolyte is eco-friendly and present no problems to the environment, it provides a good alternative for controlling microorganisms instead of chemical control. The minimum inhibitory concentration (MIC) of anolyte and its antimicrobial properties against different microorganisms in suspension was evaluated. The 1:10 and neat anolyte gave a 100% kill of all organisms tested while 1:20 dilution gave variable killing percentages ranging from 31% to 100%. Minimum inhibitory concentration was found to be 20% for most Gram positives and 50% for most Gram negatives. Anolyte did have some antimicrobial properties with MIC differing amongst different organisms. Biofilm control using different concentrations of anolyte and sodium hypochlorite was evaluated. Neat and 1:10 anolyte removed biofilm while 1:100 did not have effect on biofilm. The 100 and 300 ppm sodium hypochlorite were effective in removing the biofilm while 10, 25 and 50 ppm could not remove it. Hand wash trials and hospital disinfection using anolyte resulted in a decrease in the number of cfu/25cm3 after treatment. Effective disinfection of hands and hospital equipment was achieved. Different surfaces in a milking parlour were treated with anolyte to test its suitability to disinfect a milking parlour. High numbers of microorganisms and spreaders were observed from the plates

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before the surfaces were cleaned with anolyte. All spreaders were identified as sporeformers. Results were generally better when anolyte was used as a disinfectant, being able to eliminate spreaders as well. Treatment of chicken carcasses with anolyte to evaluate its effect on their shelf life was also tested. The number of colony forming units on chicken carcasses decreased after treatment of the carcasses with anolyte. Anolyte is therefore a naturally safe disinfectant that could be used in most fields including water distribution systems and industries for biofilm control, hospitals for minimising cross infection, food industries for increasing quality and shelf life of food and also in households for washing hands. Mr M P Thosago: MSc - Quantification of Phosphorus in Extracellular Polymeric Substance (EPS) associated with the activated sludge flocs. Supervisor: Prof T E Cloete PHD – MICROBIOLOGY Me S E Coetser: Microbial sulphate reduction in passive acid mine drainage Treatment systems Abstract The production of acid mine drainage (AMD) containing high concentrations of sulphate, heavy metals and low pH is of increasing concern. AMD is highly corrosive and results in environmental and economic problems. There is an increasing demand for inexpensive, environmental friendly technologies to remediate AMD. Passive treatment systems are such an alternative. Passive treatment systems refer to water treatment systems utilising naturally available energy sources and require regular but infrequent maintenance. Sulphate reducing bacteria have been used in pilot plant passive treatment systems for biological sulphate reduction. These systems only operated successfully for a period of 200 days. Substrate availability was the limiting factor. In order for passive treatment systems to function successfully over its design life, methods for supplying a constant feed of biodegradable carbon are required. The feasibility of cathodic hydrogen for the biological reduction of sulphate was investigated. It was found that steel-derived cathodic hydrogen is a potential electron source for biological reduction of sulphate, albeit with serious limitations. A chemical, physical and microbiological study of an existing pilot passive treatment system was conducted to identify possible causes for system malfunction and to devise remedial measures. Sulphate reduction was inhibited by the prevailing oxic conditions in the bulk of the units. In the presence of significant microbial activity, oxygen present would have been consumed during the biodegradation of organic matter. System malfunction was therefore ascribed to the lack of carbon biodegradation and thus the unavailability of readily biodegradable carbon. New methods for sustaining successful long-term operation of passive treatment systems had to be developed.


The potential use of different carbon sources to drive sulphate reduction was studied. This was done in a process for developing long-term sustainability of sulphate reduction in passive treatment systems. Potential carbon substrates were characterised according to their chemical composition and the chemical composition correlated to the carbon substrate’s sulphate reduction capacity.

This study formed the baseline for the development of a patented Degrading Packed Bed Reactor (DPBR) under the auspices of the Innovation Fund sponsored by the South African Department of Arts, Culture, Science and Technology which is ready for full-scale implementation.

PhD – Plant Pathology Mr Joseph Obagwu: PhD - Developing biopesticides for control of citrus fruit pathogens of importance in global trade, Supervisor: Prof L Korsten

university of pretoria · in food safety, biological control of fruit diseases and post harvest...

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