Isolation and basic characterization of a novel organohalide-respiring bacterium within the genus Dehalogenimonas

Abstract:

[Objective] To isolate and characterize a novel organohalide-respiring bacterium and expand the diversity of dehalogenating microorganisms. [Methods] Based on the specialized energy metabolism and antibiotic resistance of certain dehalogenating microorganisms, we adapted the dilution-to-extinction strategy in defined mineral salts medium for the isolation of an anaerobic bacterium from a dehalogenating enrichment culture. Culture purity was investigated by yeast extract addition to growth medium and PCR-RFLP analysis on 16S rRNA gene amplicon. The basic characteristics of this novel microorganism were described in terms of cell morphology, 16S rRNA gene phylogeny and the ability to utilize chlorinated compounds as electron acceptors. [Results] A novel organohalide-respiring bacterial isolate, strain GP, belonging to Dehalogenimonas genus, was obtained. Strain GP is able to dechlorinate 1,1-dichloroethene (1,1-DCE) and grow at the presence of 1 g/L ampicillin and 0.1 g/L vancomycin. Cell morphology of strain GP is irregular disc-shaped coccus with a 0.4-0.8 μm diameter. Strain GP couples growth with reductive dechlorination of 1,1-DCE and vinyl chloride to nontoxic ethene using acetate as carbon source and hydrogen as electron donor. Phylogenetic analysis indicated that the 16S rRNA gene of strain GP shares 99.5% sequence similarity to that of Dehalogenimonas formicexedens NSZ-14, which grows with different types of chlorinated compounds. [Conclusion] A novel organohalide-respiring bacterium strain GP was isolated from a dehalogenating enrichment culture. This work expands the Dehalogenimonas pangenome and provides new biomaterial for detailed biochemical and physiological characterizations of Dehalogenimonas microorganisms.