Degradation of 1,2-dichloroethane by Ancylobacter aquaticus and other facultative methylotrophs

Abstract

Cultures of the newly isolated bacterial strains AD20, AD25, and AD27, identified as strains ofAncylobacter aquaticus, were capable of growth on 1,2-dichloroethane (DCE) as the sole carbon and energy source. These strains, as well as two other new DCE utilizers, were facultative methylotrophs and were also able to grow on 2-chloroethanol, chloroacetate, and 2-chloropropionate. In all strains tested, DCE was degraded by initial hydrolytic dehalogenation to 2-chloroethanol, followed by oxidation by a phenazine methosulfate-dependent alcohol dehydrogenase and an NAD-dependent aldehyde dehydrogenase. The resulting chloroacetic acid was converted to glycolate by chloroacetate dehalogenase. The alcohol dehydrogenase was induced during growth on methanol or DCE in strain AD20, but no activity was found during growth on glucose. However, in strain AD25 the enzyme was synthesized to a higher level during growth on glucose than on methanol, and it reached levels of around 2 U/mg of protein in late-exponential-phase cultures growing on glucose. The haloalkane dehalogenase was constitutively produced in all strains tested, but strain AD25 synthesized the enzyme at a level of 30 to 40% of the total cellular protein, which is much higher than that found in other DCE degraders. The nucleotide sequences of the haloalkane dehalogenase (dhUA) genes of strains AD20 and AD25 were the same as the sequence of dhL4 from Xanthobacter autotrophicus GJ10 and GJ11. Hybridization experiments showed that the dhlA genes of six different DCE utilizers were all located on an 8.3-kb EcoRI restriction fragment, indicating that the organisms may have obtained the dhlA gene by horizontal gene transmission.

Biofiltration of airborne VOCs with green wall systems-Microbial and chemical dynamics

“…39 Xanthobacteraceae, a third VOC-favored family, consisted mostly of Ancylobacter, a facultative methylotroph capable of using organochlorines as the sole carbon and energy source. 40 Very little is known about the potential VOC-degrading bacteria in green wall settings. Russell et al 21 -to our knowledge the only earlier comparable (ie cultivation-independent) green wall study-identified Hyphomicrobium as a rhizosphere-associated genus that responded positively to both exposure to VOCs as well as to growth/maturation of the plants.…”

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.…”

Degradation of halogenated aliphatic compounds: The role of adaptation

“…DM2 [9][10][11] Pseudomonas sp. P4 [12] Xanthobacter autotrophicus [ 13] Ancylobacter aquaticus [ 14] Xanthobacter autotrophicus [ 13] Pseudornonas sp. ES-2 [ 15,16] Arthrobacter sp.…”

“…3). Both in X. autotrophicus GJ10 and Ancylobacter aquaticus, this involves two specific dehalogenating enzymes, encoded by the dhlA and dhlB genes, which have been cloned and sequenced [6,14,63]. The conversion of chloroacetate proceeds by a chromosomally encoded chloroacetate dehalogenase, that in fact belongs to the L-specific haloacid dehalogenases, as discussed above.…”