Microbial degradation of quinoline by immobilized bacillussubtilis

Abstract

Quinoline containing effluent discharged from pharmaceuticals, dyes and pesticide industries pollute the environment affecting human health due to its toxicity and nauseating odor. Quinoline is carcinogenic, mutagenic and toxic to the environment. Biotreatment is a viable process as quinoline gets easily degraded by microbes. We isolated a bacterium from the soil suspension of paper mill effluent and it was analyzed by Institute of Microbial Technology, Chandigarh from biochemical, morphological and physiological tests. The test results match with Bacillus subtilis as per the Bergey's manual of systematic Bacteriology. Quinoline mineralization by free and immobilized cells was studied. Adsorption technique was used for immobilization. 100 ppm of quinoline was completely degraded in 45 h by the free cells whereas cells immobilized on coconut shell carbon takes only 30 h. Cells on coconut shell carbon are capable of degrading even 300 ppm quinoline completely in 70 h. It was also found that cells immobilized on activated coconut shell carbon were more effective than cells on foam pieces. The optimum pH for efficient quinoline degradation was 9. The stability and recyclability of immobilized cells for 3 months at different concentrations for quinoline degradation was tested by performing an experiment. The excellent storage stability and recyclability of immobilized Bacillus subtilis can be critically used for the mineralization of heterocyclic organics in wastewater.