Biodegradation and Co‐Metabolism of Monochlorophenols and 2,4‐Dichlorophenol by Microbial Consortium

Abstract

In the present study, biodegradation of monochlorophenols (MCPs) and their co‐metabolism with 2,4‐dichlorophenol (2,4‐DCP) using mixed microbial consortium has been reported. The mixed consortium has shown 44 to 100% degradation of 50 to 300 mg L–1 3‐chlorophenol (3‐CP). While in case of 4‐CP, the degradation observed was 46 to 100% of 100 to 600 mg L−1 of initial concentrations. HPLC and spectrophotometric analysis indicated that the degradation occurred via a meta‐cleavage pathway. 4‐Chlorocatechol was observed as a common intermediate for both 3‐CP and 4‐CP degradation pathways. The transformation of 4‐chlorocatechol to maleylacetate via 5‐chloro 2‐hydroxymuconic semialdehyde indicated the complete degradation of both 3‐CP and 4‐CP. The co‐metabolic study of 2,4‐DCP in the presence of MCPs showed that the degradation of 2,4‐DCP increases in the presence of 3‐CP and 4‐CP. The biodegradation (mg L−1 per day) in the quaternary mixture of MCPs and DCP occurred in the order of 3‐CP > 4‐CP > DCP > 2‐CP. The biodegradation kinetics constants obtained for 3‐CP were Rm = 1.96 mg L−1 h−1, Ks = 47.23 mg L−1, Ki = 104.12 mg L−1, and for 4‐CP were Rm = 6.33 mg L−1 h−1, Ks = 1262 mg L−1, Ki = 1408.8 mg L−1 by Andrew's substrate inhibition model using MATLAB 6.5.