Degradation of halogenated aliphatic compounds by Xanthobacter autotrophicus GJ10

Abstract

A bacterium that is able to utilize a number of halogenated short-chain hydrocarbons and halogenated carboxylic acids as sole carbon source for growth was identified as a strain of Xanthobacter autotrophicus. The organism constitutively produces two different dehalogenases. One enzyme is specific for halogenated alkanes, whereas the other, which is more heat stable and has a higher pH optimum, is specific for halogenated carboxylic acids. Haloalkanes were hydrolyzed in cell extracts to produce alcohols and halide ions, and a route for the metabolism of 1,2-dichloroethane is proposed. Both dehalogenases show a broad substrate specificity, allowing the degradation of bromine-and chlorine-substituted organic compounds. The results show that X. autotrophicus may play a role in the degradation of organochlorine compounds and that hydrolytic dehalogenases may be involved in the microbial metabolism of short-chain halogenated hydrocarbons in microorganisms.

Distribution, sources, and stability of haloacetic acids in Tokyo Bay, Japan

“…Bromoacetic acids are better substrates than the corresponding chloroacetic acids for bacterial enzymes called haloacid dehalogenases. The order of reactivity was as follows: MBAA Ͼ MCAA [30,32,33], DBAA Ͼ DCAA [33]. These are consistent with the order of magnitude of bond dissociation energy between carbon and halogen [39].…”

“…Haloacetic acids (2-halogenated alkanoic acids), such as MCAA [28][29][30][31][32][33][34][35][36], DCAA [28][29][30][31][32][33][34][36][37][38], TCAA [28,30,32], MBAA [30,32,33,35,36], and DBAA [33,36], have been reported to be decomposed by bacterial enzymes called haloacid dehalogenases. Dehalogenases catalyze the hydrolysis of halogen-substituted alkanoic acids, yielding either hydroxyalkanoic acids from monohalogenated acids or oxoalkanoic acids from dihalogenated compounds [30].…”

“…The order of reactivity of chloroacetic acids was as follows: MCAA Ͼ DCAA Ͼ TCAA [28,30,32]. For some enzymes of bacteria, DCAA is a better substrate than MCAA [29,31,33,36]. However, enzymatic decomposition of trichloroacetate was small.…”

Isotope analysis as a natural reaction probe to determine mechanisms of biodegradation of 1,2‐dichloroethane

“…To date, under aerobic conditions, 1,2-DCA is thought to be biodegraded via enzymatically initiated hydrolytic dehalogenation (C-Cl bond cleavage) or oxidation (C-H bond cleavage) reactions ( Fig. 1) (Janssen et al, 1985;Van Den Wijngaard et al, 1992;Hage and Hartmans, 1999). Under anaerobic conditions, 1,2-DCA biodegradation via a reductive dechlorination reaction (C-Cl bond cleavage), dihaloelimination reaction (cleavage of two C-Cl bonds and formation of a C=C double bond) and mineralization to CO 2 (Fig.…”

Trihalomethane Cometabolism By A Mixed‐Culture Nitrifying Biofilter

“…HAA biodegradation is not at all surprising because the ability of mono-and dichloroacetic acid to support microbial growth is well D filtration The published report, Cometabolism of Trihalomethanes in Nitrifying Biofilters (91100F), is available from IWA Publishing at www.iwap.co.uk or is free to AwwaRF subscribers by calling 303-347-6121 or logging on to www.awwarf.org. documented in the microbiology and hazardous waste literature (Janssen et al, 1985;Motosugi & Soda, 1983).…”