Biodegradation of Pyrene Using Bacillus sp.C7 Isolated from Coal Deposited Soil

Abstract

Aims: To evaluate the efficiency of bacterial isolates in pyrene degradation. Place and Duration of Study: The study was carried out at School of Life Sciences, S.R.T.M. University, Nanded, (M.S.), India during June 2015 and March 2016. Methodology: Coal deposited soil was collected and used for isolation of pyrene degrading bacteria. The isolation of bacteria was carried out following three successive enrichments of soil sample in Bushnell Haas broth supplemented with 200, 400 and 1000 mg/L pyrene respectively. The morphologically distinct 10 bacterial isolates obtained on Bushnell Haas agar medium supplemented with 1000 mg/L pyrene as sole carbon and energy source were screened for pyrene degradation ability by DCPIP assay. The efficient pyrene degrading Bacillus sp. C7 was selected and used for further studies. The parameters in terms of pyrene concentration, pH of the medium, temperature, incubation period and suitable surfactant, carbon and nitrogen source were optimized using OVaT approach. Results: The efficient pyrene degrading strain C7 was selected and identified on the basis of morphological and biochemical characterization as Bacillus sp. C7. The strain was able to catabolize 81.53% of pyrene (1000 mg/L) within 20 days of incubation. The strain showed highest pyrene degradation at 1000 mg/L, 30°C, pH 7.0, after 20 days of incubation and in the presence of tween-80, glucose as co-metabolite and beef extract as nitrogen source. Conclusion: The study identified a pyrene degrading soil bacterium Bacillus sp. C7. The optimization approach used in the study revealed tween-80, glucose and beef extract are principle components for pyrene degradation. Overall 5.17% rise over control in pyrene degradation was observed after optimization studies.