Screening of PAH-degrading bacteria and studies on their degradation characters

PAH-degrading microbes CNWL2 and CNWL6 were isolated from bottom sludge of coking wastewater. By using the technique of bacterial adherence to hydrocarbons (BATH), cell-surface properties of the two strains,had been investigated, and by using shaking flask test, MPN method and UV Spectrophotometric Method, their degradation properties for pyrene and the influence of some metabolic intermediates on the degradations had also been studied. The results indicated that cell surface of CNWL2 is with strong hydrophobicity and that of CNWL6 is with strong hydrophilicity. Both CNWL2 and CNWL6 could decompose pyrene and the biodegradation rate was higher by CNWL2 than by CNWL6. For CNWL2, the pyrene degradarion rate can be enhanced 25% and 16% by adding phthalic acid and glucose respectively. CNWL6, with higher hydrophilicity, displayed high adsorptivity to pyrene, and its pyrene-degrading process could be inhibited by adding plithalic acid and glucose in cultural liquid. The pH values of biodegrading medium were fluctuating up and down continuously, this pH value fluctuations were resulted from accumulating of acidic metabolic intermediates and further decarboxylation of such intermediates.