Biodegradation of phenol in batch culture by pure and mixed strains of Paenibacillus sp. and Bacillus cereus.

The bacterial strains, Paenibacillus sp. (AY952466) and Bacillus cereus (DQ002384), have proven capacity to degrade lignin and pentachlorophenol. In the present study, both strains were screened at different concentrations of phenol on mineral salt agar medium in the presence of glucose. At optimized condition (pH 7.5 +/- 0.2, 37 +/- 1 degrees C, 120 rpm, 1% glucose w/v), it was observed that both Paenibacillus sp., B. cereus and its mixed culture degraded phenol (500 mg/l) up to 53.86%, 91.63% and 67.76% within 168 h of incubation, respectively. Phenol degradation was routinely monitored spectrophotometrically and further confirmed by HPLC. Catechol and 2-hydroxy muconic semialdehyde were identified as intermediate products from degraded samples using GC-MS. It was also observed that, in the absence of glucose, bacterial strains were unable to utilize phenol indicating the phenomenon of co-metabolism.