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CHEMOORGANOTROPHIC MICRO-ORGANISMS AS AGENTS IN THE DESTRUCTION OF OBJECTS OF ART- A SUMMARY

KRUMBEIN, WOLFGANG E.; DIAKUMAKU, EUGENIA; GEHRMANN, CORNELIA;

Carl von Ossietzky Universittlt Oldenburg, Postfach 2503, 26111 Oldenburg, Germany

GORBUSHINA, ANNA A. ;

Dept. of Botany, St. Petersburg State University, St. Petersburg, Russia

GROTE.GABI; HEYN.CHRISTIANE; KUROCZKIN,JOANNA; SCHOSTAK,VOLKER; STERFLINGER,KATJA;

Carl von Ossietzky Universitat Oldenburg, Postfach 2503, 26111 Oldenburg, Germany

WARSCHEID, THOMAS;

MPA Bremen, Paul-Fellerstr. 1, 28199 Bremen

WOLF, BRIGITIE;

Institute of Agricultural Engineering Bomim e.V., Max-EythAllee 100, D-14469 Potsdam, Germany

WOLLENZIEN, UTE; YUN-KYUNG YUN; PETERSEN, KARIN;

Carl von Ossietzky Universitat Oldenburg, Postfach 2503, 26111 Oldenburg, Germany

SUMMARY For many years it was generally thought and written that the Potential attack and destructive action of micro-organisms on monuments and other objects of art especially under outdoor conditions is initiated by photoautotrophic and lithoautotrophic organisms. These would derive their energy from the sun or inorganic substances of the rock and their carbon and mineral nutrition from the inorganic materials on which they dwell. Rocks, glasses and metals do not contain organic materials in sufficient amounts to directly sustain chemoorganotrophic biological growth and hereby biodeterioration. However, Krumbein (1966, 1988) has already contributed data concerning the possibifity that micro-organisms, which depend on organic energy sources can settle on and in inorganic materials deriving their energy and mineral materials mainly from gaseous, dissolved and particulate organics and inorganics in the atmosphere. In this contribution a summary is made of 30 doctorate and M. Sc. theses dealing with the interactions of micro-organisms with rock and mineral material surfaces and the detrimental influences of the microflora as well as with the possibilities to interfere with them by treatment techniques. It is stated and supported by data that chemoorganotrophic micro-organisms settle in large numbers on mineral surfaces and penetrate into the mineral materials. Organic aerosols in contrast to inorganic air pollutants such as sulfur and nitrogen compounds have had a constantly increasing tendency in Europe over the last 50 years. The bacterial and fungal biofilms thus are increasingly favoured and especially those types which we designated as poikilotrophic microorganisms (Krumbein, 1988). The poikilotrophic micro-organisms have the following effects on the environment in which they live:

1. They excert a physical attack on the chemically weakened materials by desintegrating them in part; creating chipping, exfoliation, sanding and pitting structures. The main physical factors of attack are biofilm Potential of differential drying and wetting, the water hydrostatic pressure, drilling of hardened cell walls and penetration units (Gorbushina et al., 1993) and differential

heating (Gorbushina, 1996 ). 2. They contribute largely to or are the causes of a chemical solution and change of the above

mentioned materials to an extent that largely exceeds the monument realm and influences the

global geochemical budgets (Krumbein and Lapo, 1996; Thorseth, 1995). 3. They create patinas or crusts, which are not a product of transformation of rock material but a

product of deposition and transformation of external substances derived from the atmosphere. 4. The best means of controlling the detrimental air-supported microflora and biofilms may be

repeated cleaning processes not unlike prophylaxis in dental care although, in cases, antibiotic or biocide treatments may be considered especially in the case of very valuable monuments" using

the necessary precautions.

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1. INTRODUCTION

The question whether or not microbes and if, which metabolic types are active in the deterioration

of rocks, minerals and other hard substrates on and in which they are observed and alive is as old as the

Holy Script. The solution and quantification of the problem is far from being solved. There is general agreement about a few facts, however. (1) Microbes can be detected on and below any surface analysed

for their presence. They are just there. (2) The main question is and remains today after many years of detailed research: If they are there and if they live what are they doing? Do they play an important role? (Thorseth, 1995; Krumbein, 1966, 1988; 1996). Within a Generation of scientific wisdom development the geomicrobiology group of the Carl von Ossietzky University Oldenburg has struggled with this question without finding a definite answer. (3) Thus it remains to be said in the introductory remarks to this contribution that more work needs to be invested and more money needs to be spent in order to really penetrate deeper into the mutual relationship between micro-organisms and rock or mineral surfaces. Krumbein and Lapo (1996) in summarizing life-long struggles for understanding have implied

that life is a universal constant and thus inevitably influences and interferes with all possible physical and chemical processes including the wear down of rocks and thus also of monuments. Even more: Rocks of monuments, rocks of deserts and volcanic glass lavas of the Deep Sea are as alive as a coral reef or a termite hive. Many scientists have contributed facets and details to this major question. In the references to this article more or less exclusively those M. Sc. theses and Ph. D. theses are quoted which were in the hands of the main author (Krumbein, 1966, 1988, 1995) as referee or supervisor. Thus the conclusion of 30 years of work may be a totally subjective one.

Still it is interesting to note that the progress of the field is slow, but steady. Many others have contributed, who are not quoted here for lack of space. The range of interest and of topical approaches, however, spans practically the globe. It is feared by the authors (all of them) that the life-time of an average biologist is not sufficiently long to really witness considerable and important progress in this field and in solving this question. All we wish to do in this short contribution to the 8th International Congress on the deterioration and conservation of stone is to enable other biologists (and scientists of other disciplines) to follow the complex pattern of scientific research in the field of biodeterioration by gaining access to a large number of theses which were published often only in part or not at all.

2. MATERIAL AND METHODS

All materials and methods used for this contribution are summarized in the multitude of theses referenced in the reference list. They encompass physical, chemical and biological techniques including increasingly also the so-called molecular ecological techniques of macromolecular analyses of microbe associations and their biodiversity. It is not really important to describe here all the techniques, which were applied. Cultivation techniques e.g. were described in detail by Krumbein (1966), Braams (1992), Diakumaku (1996), Sterflinger (1995), Warscheid (1990) and many others. The techniques applied and . partially developed in our laboratory encompass a great deal of the physical, chemical, microbiological and molecular biological approaches possible. Many of them are traditionally changed and modified, others are stable and unchanged for almost 100 years (e.g. the Gram stain for differentiating chemo­organotrophic and chemolitho-autotrophic bacteria). Rocks from all continents including the Antarctic and from many Seas have been analysed and microbes of all physiological and taxonomic groups have been studied. The work (and the progress) was as has been said before- tedious and slow and comparable to the blind Person having the task to seek for the needle in the hay-stack. For-tunately many new techniques have been developed in order to penetrate deeper into the Problems (e.g. Schostak, 1993; Rolfes, 1991 ; Gehrmann, 1995; Sterflinger, 1995; Diakumaku, 1996; Gorbushina, 1996)

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3. RESULTS AND DISCUSSION

The results of 30 years of empirical and experimental work of our laboratory on the question of the biodeterioration of rocks and minerals are somewhat poor and frustrating for the workers and authors.

It is, however, possible today to strongly suggest, imply and in some cases even quantitatively determine, that microbes destroy rocks and that this process is faster than exclusively physical­chemical destruction (Krumbein, 1966; Warscheid, 1990; Sterflinger 1995; Diakumaku, 1996). It has further been shown that practically all groups of microorganisms can be found on and within rocks and that the latter may have an influence on the physical and chemical behaviour of rock surfaces. This includes small to microscopic (higher) plants or their parts, lichens, fungi, algae, cyanobacteria, and literally all major groups of bacteria including the actinomycetes and the archaebacteria. The number of strains isolated in culture exceeds 1000 and the number of species, in the fungi e.g. exceeds 150, in the actinomycetes a minimum of 40 (Chamier. 1991 ; Eppard, 1995; Gorbushina et al., 1996; Grote, 1991 ;Petersen et al-, 1995; Schlemminger, 1987; Sterflinger, 1995; Wolf, 1996; Wollenzien, pers. comm.)

Quite early in our work a definition was given of biotic and abiotic rock decay and the processes involved. This definition (Krumbein, 1966, 1988) is still in use and is developed further with new findings:

(Bio-)corrosion, (bio-)deterioration or (bio-)weathering is an exchange or biotransfer of material (atoms) and energy between two heterogenous open systems: the (solid) substrate (rock, brick, concrete, mural painting, glass, wood, paper, parchment etc.) and the gaseous or liquid (sometimes solid) environment. Both systems are defined by their physical properties (mass, volume, humidity, temperature, pressure, porosity, hardness, degree of crystallisation etc,), chemical composition (number and coordination of atoms) and their living (or life) properties (sets of genetic information, time-space relations of dissymetric transfer of atoms and energy through membranes under drastic changes of the immediate molecular and physical-chemical environment). The mutual interaction of all components and processes leads to a more or less complete turnover of the initial materials at the border zone between the two systems. The natural lin-lit of the turnover phenomena and processes is given by the penetration depth or extension of physical and chemical as well as biological gradients and of the movement of atoms, ions, chemical compounds and organisms or their metabolic products and forces. This (bio-)transfer

- process may come to a stillstand within the space-time continuum (e.g. through patina or crust or biofilm formation). It may, however, be revived if only one of the components of the complex

system or processes involved changes or is submitted to change.

Naturally this all-embracing definition of weathering, wear-down or cyclic transformation can also (with some modifications) be regarded as a definition of life itself. This is not so astonishing inasmuch as some authors hold it that life on Earth and the life of Earth established itself at first in wet rock cavities and, that life processes may also be at the basis of Plate Tectonics, morphogenesis and the associated temperature and climate effects in the atmosphere (Krumbein and Lapo, 1996).

The main findings in the long sequence of dissertations" however, are interesting enough to be

explained more explicitly in this short resume of our work.

(1) It became more and more clear that there is a major similarity between man and rock dwelling

microbes. Man uses caves or builds houses to live in them. He, however, does not ,use the material of the cave

or of the house for maintenance and food (energy and material flow and supply). Microorganisms use cavities or produce cavities or shelters (patina, crust) to live in them. Energy

sources and building blocks for cellular material and turnover, however, come mainly from the

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atmosphere (polluted or unporuted) with some additions by rain washing materials down surfaces or

ground water migrating upwards with the atoms and ions dissolved in the liquid. (2) The microflora of rocks is very specialized and practically worldwide distributed. Among all groups of

microorganisms encountered on monuments (phototrophs, chemolithotrophs, chemoorganotrophs) the so-called poikilotrophic micro-organisms are dominant (Krumbein, 1988). In contrast to the oligotroph organisms (growing slowly and exclusively but constantly at low levels of energy and

nutrient sources) and the copio-/or zymotroph organisms (growing fast on rich energy and material sources and then interrupting growth by forming propagation, spreading or resting structures such as

spores or other enduring cellular products or entities) the poikilotroph organisms will not be ''tricked" either by very poor conditions or outbursts of very rich energy and material sources. The main and foremost characteristic of the poikilotroph organism is the fact that all cells formed will be equipped and apt to survive low energy conditions, low nutrient supply and adverse environmental physical and chemical conditions. The poikilotroph organism is robust, enduring, slow growing. It does not form special resting bodies or spores. Survival strategies are including all cells and structures produced during vegetative growth. The strategy of the poiklilotroph is to keep all cells formed alive and protected as long as possible. It will cope with high and low temperatures, high and low acidity and irradiation, prolonged periods of dryness, lack of energy sources and building blocks for cellular units and other sporadically occurring or ephemeral phenomena in the space-time field. By this it will be characterized by reduced ability of exchange of atoms and energies 'between the interior and exterior of the cell due to thick and resistant cell walls, envelopes and meristematic structures. All these features on one hand reduce the exchange capacity between the biological system of the poikilotroph and the bioinert natural bodies in its environment and on the other hand make such organisms very resistant to cultivation attempts. Many of them are observed on rocks but cannot be taken into culture (Gorbushina et al., 1993).

(3) The speed of deterioration or decay of rock material in monuments is markedly accelerated in comparison to (artificially produced) sterile rock. No rock in the natural environment is sterile. Even the deep biosphere of the marine sediments and volcanic glasses occurring there in more than 500 m depth below the ocean bottom (sediment/water interface) are populated by a rich flora causing biocorrosion (Thorseth, 1995). The acceleration factor is between 1 O times and 10.000 times as compared to physical chemical decay under normal enviro=ental conditions. This has been empirically derived in field observations on monuments and experimentally proved in laboratory simulations (e.g. Gorbushina et al., 1993; Sterflinger, 1995, Diakumaku, 1996; Krumbein, 1966, 1995; Wollenzien, personal communication).

(4) Pitting, chipping, desquamation, exfoliation sanding, patina and crust development are all under biological control and can be reproduced in laboratory experiments using the microorganisms isolated from rock (e.g. Braams, 1992; Diakumaku, 1996; Gorbushina et al, 1993, 1996; in press; Sterflinger, 1995).

(5) The rock microflores are varying from place to place and with time. In a real space-time relation e.g. there may exist successions of freshwater microbes, moderately halophilic and halotolerant, extremely halophilic and halotolerant, moderate and extremely alkal.itolerant communities with the changing titration and chromatography of salts in a given rock or porous medium like a mural painting (Schostak, 1988, 1993; Petersen et al., 1995). Thus for many years only fractions of the real rock microflora were observed and analysed because no specialised media for enrichment and isolation were applied.

(6) The rock microflora is a specialized one. In contrast to previous findings also in our laboratory it has to be envisaged now that at least three different and recognizable groups of lower fungi are typically inhabiting rocks under different environmental conditions, different growth regimes and

using di~~rent adaptation st~ategies. These r~nge from two interconnected types of oligotrophy over po1k1lotrophy to sporadic outbursts of cop1otroph fungi. Several different factors play an

im~ortant role in ~he li~e cycles and ~ife strategies of rock dwelling fungi , which may perhaps ~lt1mately be dev1ded into several different groups or strategies. The principle of dimorphism itself may first have been developed by fungi in such environments (Gorbushina et al. 1993 Gorbushina et al. , in press; Sterflinger, 1995; Sterflinger and Krumbein, 1995). '

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(7) Practically all minerals including organic minerals such as citrates and oxalates, sulfates and carbonates, oxides and hydroxides and even several different species of silicates including Quartz can be dissolved, corroded, eroded but also created or deposited by microbial mineral

transfonnation near the rock surface and deposited in microbial biofihns and microbial mats of the biokarst type (Braams, 1992; Gehnnann. 1995; Gorbushina et al., 1996).

(8) One of the most striking findings of these 30 years of work is, however, the following: Microbes act in and on rocks rather directly by physical and mechanical action and not only -as assumed for many years- by chemical solution/precipitation reactions and subsequent physical actions of the minerals (Mellor, 1922; Gorbushina et al., 1993, Gorbushinal, 1996).

(9) Further in terms of microbial interaction between rock surface and the surrounding atmosphere the concentrations of organics and of humidity are much more important than those of inorganic compounds. Thus not only sulfur and nitrogen pollution but especially organic pollution endangers rocks and mural paintings by initiating and accelerating microbial infection, biofilm fonnation and microbial mat dynamics on and in mineral substrates.

(10) A hypothesis of Hutton (1788). revived by Vernadsky (1929) and modified by Krumbein (1983) and Krumbein and Lapo (1996) states: Earth is an organism (Ten-a sempervirens). Earth has an epithelium which can be studied by the use of parahistology -a tenn coined by Wachendorfer (1991 )- and most of the life processes on and of Earth are controlled by the active and dissymetric flow of energy and atoms through this epithelium (or the individual organismal membrane). Microbial mats and biofilms not only rule the marine and lin-Lnic sediments but also soils and the bare rock surfaces. All physical and chemical processes on Earth (including the decay of man made monuments) thus are indirectly and directly controlled by the spacetime relationships within the frame of a living natural body or (if preferred) living natural bodies.

ACKNOWLEDGEMENTS The doctorate theses on which this article is based were supported by several grants of the Acropohs Comittee (Greece). BMBF (Federal Ministery of Science). CEE (Comission of the European Communities). DBU (National Environment Foundation). DFG (National Science Foundation), VW­Stiftung (Volkswagen Foundation) and naturally the enthusiasm and dedication of many generations of M. Sc. and Doctorate students together with our skilled technicians.

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