Abhishek Jaiswal_078

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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

Transcript of Abhishek Jaiswal_078

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.

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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.

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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in 100 mL liquid medium in 250 mL Erlenmeyer flasks and incubated at 37 oC under static condition. 2 mL of samples were withdrawn at regular time interval up to complete dye decolorization.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)

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Result and discussions

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Mediated decolorization of RV5 by Stenotrophomonas maltophilia

Effect of AQS concentration on mediated RV5 decolorization by S. maltophilia

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Effect of inoculums size on AQS-mediated RV5 decolorization

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Effect of glucose concentration on AQS-mediated decolorization ofRV5

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Effect of yeast extract on AQS-mediated RV5 decolorization

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Effect of shaking and static condition on AQS-mediated RV5 decolorization

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Effect of KNO3 (10 mM) and NH4Cl (10 mM) on AQS-mediated RV5 decolorization

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Effect of potassium nitrate on AQS-mediated RV5 decolorization

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Effect of pH on AQS-mediated RV5 decolorization

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Effect of temperature on AQS-mediated RV5 decolorization

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Effect of RV5 and glucose on AQS mediated RV5 decolorization

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Effect of RV5 and yeast extract (YE) on AQS-mediated RV5 decolorization

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Quinine reductase activity of Stenotrophomonas maltophilia grown in presence and absence of AQS (1mM) and RV5 (50 mg/L)

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Thin Layer Chromatogram of RV5 and degraded metabolites of RV5 (L1: Abiotic RV5 control, L2: Decolorized RV5)

 

L1 L2

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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.

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Thank you….