Critical steps in degradation of chloroaromatics by rhodococci IV. Detailed kinetics of substrate removal and product formation by resting pre‐adapted cells

Abstract

AbstractIn kinetic experiments it was demonstrated that turnover of various monochloroaromatic non‐growth substrates (i.e. 2‐chloroaniline, 3‐chloroaniline, 3‐chlorophenol, 4‐chlorophenol, 3‐chlorobenzoic acid) by resting pre‐adapted cells of Rhodococcus sp. An 117 or An 213 typically results in the accumulation of cis‐4‐carboxymethylene‐but‐2‐en‐4‐olide as the principle dead‐end product while cometabolic 2‐chloroaniline turnover by resting aniline‐grown cells of Rhodococcus rubropertinctus IMET 7481 yielded nearly stoichiometric amounts of 2‐chloro‐cis,cis‐muconic acid. Evidence is presented that the observed cometabolic effect of glucose on turnover of the respective monochloroaromatics is primarily associated with their initial oxygenative conversion into chlorocatechols. Based on the described experimental data, it was concluded that the failure of rhodococci to bring about total degradation of chloroaromatics through chlorocatechols is mainly due to the absence in these organisms of a modified ortho‐cleavage pathway (i.e. maleylacetatepathway).