abhishek jaiswal_078
TRANSCRIPT
Anthraquinone-2-sulfonate mediated decolourization of Reactive violet 5 by Stenotrophomonas maltophilia
Abhishek Jaiswal M.Sc Microbiology
Exam no. – 078
B.R.D School of Biosciences
Introduction
Dyes are organic chemical compounds, which impart colour to other materials by saturating them in aqueous solution. Synthetic dyes have a wide application in the food, pharmaceutical, textile, leather, cosmetics and paper industries due to their ease of production, fastness and variety in colour compared to natural dyes. Dyes are designed to remain stable and long-lasting colorants which are usually not easily biodegraded.
Azo dyes are considered as electron-deficient xenobiotic compounds because they possess azo bond (R1–N=N–R2) and other electron-withdrawing groups, generating electron deficiency in the molecule and making the compound less susceptible to oxidative catabolism by bacteria. As a consequence, azo dyes tend to persist under aerobic environmental conditions.
Abhishek Jaiswal
Objectives
• To study the mediated decolourization of RV5 by Stenotrophomonas maltophilia.
• To optimize physico-chemical parameter for efficient AQS-mediated RV5 decolourization.
• To determine quinone reductase in Stenotrophomonas maltophilia grown in presence of dye and AQS.
• To demonstrate degradation of RV5 by Stenotrophomonas maltophilia using thin layer chromatography.
Abhishek Jaiswal
Materials and methods
Stenotrophomonas maltophilia was already isolated in our laboratory and maintained on Luria Bertani (LB) medium. Decolorization of reactive violet 5 (RV5) was performed in modified Bushnell and Hass Mineral (BHM).
Overnight grown culture of S. maltophilia was inoculated in 100 mL liquid medium in 250 mL Erlenmeyer flasks and incubated at 37 oC under static condition. 2 mL of samples were withdrawn at regular time interval up to complete dye decolorization. Growth of culture was measured at 660 nm and RV5 color was measured at 558 nm. The percent decolorization and decolorization rate were calculated as follow:
Decolorization (%) = (Initial dye concentration – final dye concentration) × 100
Initial dye concentration
Decolorization rate (mg/L.h) = Initial dye concentration – Final dye concentration (mg/L)
Time withdrawn for decolorization (h)
Abhishek Jaiswal
Result and discussions
Abhishek Jaiswal
Mediated decolorization of RV5 by Stenotrophomonas maltophilia
Quinine reductase activity of Stenotrophomonas maltophilia grown in presence and absence of AQS (1mM) and RV5 (50 mg/L)
Abhishek Jaiswal
Thin Layer Chromatogram of RV5 and degraded metabolites of RV5 (L1: Abiotic RV5 control, L2: Decolorized RV5)
L1 L2
Abhishek Jaiswal
Summary and conclusion
• Mediated decolorization of reactive violet 5 by Stenotrophomonas maltophilia under static condition was investigated. Different redox mediators used during this work were anthraquinone-2-sulphonate, anthraquinone-2, 6-disulphonate, lawsone and ethyl viologen in which AQS was found to be most suitable for efficient dye decolorization.
• The maximum decolorization rate of RV5 by S. maltophilia was observed in presence of 2 mM AQS in medium containing 0.05 % (w/v) glucose, 0.05 % (w/v) yeast extract, 20 mM KNO3 as inorganic nitrogen source, initial pH 7.5 and an inoculum size of 0.1 O.D.660 nm
under static incubation at 37 ºC.• Increase in intracellular quinine reductase activity was observed in
presence of AQS, suggesting its role in reduction of AQS to AQSH2, which may be ultimately involved in reduction of RV5.
• Degradation of RV5 could be demonstrated by silica gel thin layer chromatography.
Abhishek Jaiswal