Isolation & Characterization of an unknown bacterium from an industrial waste water and study of its azo dye decolourisation and degradation capability Puspita Bhattacharya, Dr.Papita Das* INTRODUCTION RESULTS Azo dyes are Chemically & photolytically stable, highly persistent in natural environment causes ecotoxic hazards, highly mutagenic, carcinogenic, introduces potential danger of bioaccumulation in human body Congo red is the sodium salt of 3,3'-([1,1'-biphenyl]-4,4'-diyl)bis(4-aminonaphthalene-1-sulfonic acid), formula: C32H22N6Na2O6S2; molecular weight is 696.66 g/mol) The waste water sample was collected from a waste disposal site of a textile processing and dying industry near Rajarhat (Kolkata, West Bengal, India) The decolorization experiment was done by inoculating loopful of bacterium into 100 ml of MSM in 250 ml conical flask at at 30o c and 130 rpm Effect of various dye concentrations The effect of different concentrations of congo red on decolorization was observed by taking 50-500 mg/l respectively, the required time was 4 hr, 8 hr, 24 hr, 30 hr. Increasing concentration of Congo red repress the percentage of decolorization. The dye decolorization rate was decreased after 500 ppm Effect of various pH pH of the medium was varied from 3-9 and as the pH increases from 7 the % of decolorization gradually decreases with further decrease in pH At pH 3, the removal of the dye was maximum and at pH 9, the removal of the congo red dye minimum Effect of inoculum concentration Inoculum % was varied from 5-20% and the required time for the removal was 6 hr,18 hr,21 hr,24 hr and 32 hr and % of removal of congo red was decreased with increase in inoculum percentage % of dye removal of congo red dye with increase in pH at a concentration of 70 mg/l AIM Percentage of the dye removal with increase in inoculum concentration This study presents biological decolourization of congo red through a microbial isolate obtained from dye contaminated textile effluent To obtain the maximum operating condition for the dye removal by changing the parameters i.e. Concentration range, pH and the inoculum percentage for the bacterium METHODS Isolation and screening of the bacterium Serially diluted soil sample was plated on nutrient agar plate supplemented with 50 mg/l congo red dye, bacterium capable of growing on the plates were isolated and the bacterium was further screened in the mineral salt medium( MSM) agar plate supplemented with 1% glucose and 0.5g/l yeast extract for confirmation of its dye degrading capability and to obtain pure culture Composition of the mineral salt medium (MSM): 1.CaCl2, 2H20- 0.04 2.KH2PO4- 0.1 3.NaCl- 0.8 4.NH4Cl- 1.0 5.MgSO4,7H2O- 0.2 6.KCl- 0.1 7.CoCl2,6H2O- 0.1mg/l 8.MnCl2,4H2O- 0.425 mg/l 9.ZnCl2- 0.05 mg/l 10.CuSO4,5H2O-0.015 mg/l 11.NiCl2,6H20- 0.01mg/l 12.Na2MoO4-0.01 mg/l 13.Na2SeO4-0.01mg/l 14. Agar- 30g/l CONCLUSION The isolated microorganism has a potential for the removal of congo red dye at a higher concentration and the bacterium works well in the acidic pH and as the pH increases, the percentage of removal decreased. The percentage of removal also decreased with increasing in the concentration of the dye . REFERENCE Banat, I.M., Nigam, P., Singh, D. & Marchant, R. 1996 Microbial decolorization of textile dye containing effluents: a review. Bioresource Technology 58, 217–227 Bras, R., Ferra, I.A., Pinheiro, H.M. & Goncalves, I.C. 2001 Batch tests for assessing decolorization of azo dyes by methanogenic and mixed cultures. Journal of Biotechnology 89, 155–162 Characterization of aerobic azo dye degrading bacteria and their activity in biofilms. Water Science and Technology 36, 215–220. Percentage of decolourization of congo red at various dye concentration.