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

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 R_m = 1.96 mg L⁻¹ h⁻¹, K_s = 47.23 mg L⁻¹, K_i = 104.12 mg L⁻¹, and for 4-CP were R_m = 6.33 mg L⁻¹ h⁻¹, K_s = 1262 mg L⁻¹, K_i = 1408.8 mg L⁻¹ by Andrew's substrate inhibition model using MATLAB 6.5. [ABSTRACT FROM AUTHOR]