Enhancement of cometabolic biodegradation of 4-chlorophenol induced with phenol and glucose as carbon sources by Comamonas testosteroni

Abstract

The biological degradation of phenol and 4-chlorophenol (4-CP) by Comamonas testosteroni CECT 326T has been studied. Phenol and 4-CP were treated alone as a sole carbon and energy source, but only phenol was completely degraded by C. testosteroni. Since the presence of cosubstrates can enhance the toxic compounds removal by pure cultures, phenol and glucose were added as growth substrates for cometabolic transformation of 4-CP. High efficiencies were obtained in all the experiments carried out in presence of both cosubstrates. In spite of the fact that the addition of glucose reduced the lag phase of 4-CP removal, lower phenol concentrations were required to obtain the same degradation efficiencies. The cometabolic transformation of 4-CP was closely related with the extent of phenol removal. The values of the 4-CP/biomass concentration ratio (S/X) obtained for discriminating between complete (S/X ≤ 0.11) and partial 4-CP (S/X ≥ 0.31) transformation showed a narrower range than that reported in the literature. The extent of the cometabolic 4-CP transformation in the presence of phenol could be further enhanced by using glucose as an additional carbon and energy source. However, no significant influence of glucose concentration on 4-CP removal was observed over the concentration range studied.