Characterisation of Arthrobacter sp S1 that can degrade α and β-haloalkanoic acids isolated from contaminated soil

A bacterium identified as Arthrobacter sp. S1 by 16S rRNA was isolated from contaminated soil. This is the first reported study that Arthrobacter could utilize both alpha-halocarboxylix acid (alpha HA) [2,2-dichloropropionic acid (2,2-DCP) and D,L-2-chloropropionic acid (D,L-2-CP)] and beta-halocarboxylix acid (beta HA) [3-chloropropionic acid (3CP)] as sole source of carbon with cell doubling times of 5 +/- 0.2, 7 +/- 0.1, and 10 +/- 0.1 h, respectively. More than 85 % chloride ion released was detected in the growth medium suggesting the substrates used were utilized. To identify the presence of dehalogenase gene in the microorganism, a molecular tool that included the use of oligonucleotide primers specific to microorganisms that can grow in halogenated compounds was adapted. A partial putative dehalogenase gene was determined by direct sequencing of the PCR-amplified genomic DNA of the bacterium. A comparative analysis of the deduced amino acid sequence data revealed that the amino acid sequence has a low identity of less than 15 % to both group I and group II dehalogenases, suggesting that the current putative dehalogenase amino acid sequence was completely distinct from both alpha-haloacids and beta-haloacids dehalogenases. This investigation is useful in studying the microbial populations in order to monitor the presence of specific dehalogenase genes and to provide a better understanding of the microbial populations that are present in soil or in water systems treating halogenated compounds.