Brooklawnia cerclae gen. nov., sp. nov., a propionate-forming bacterium isolated from chlorosolvent-contaminated groundwater

Abstract

Two novel facultatively anaerobic bacterial strains, BL-34T and BL-35, isolated from groundwater contaminated by a mixture of chlorosolvents were characterized using a polyphasic approach. The two strains exhibited essentially identical taxonomic features except for a vitamin B12 requirement by strain BL-35 for optimal growth. Phylogenetically, the isolates were affiliated with members of the family Propionibacteriaceae and were placed in a phylogenetic branch adjacent to, but distinct from, those of the genera Propionimicrobium, Propionibacterium, Luteococcus, Propioniferax and Tessaracoccus. The cells of the novel strains were Gram-positive, non-motile, non-spore-forming pleomorphic rods. They produced catalase but not oxidase, and nitrate reduction did not occur in peptone/yeast extract/glucose medium. Propionate and acetate were the predominant products of glucose fermentation. Fermentation occurred in the presence of 1,2-dichloroethane and 1,1,2-trichloroethane at concentrations up to at least 9.8 mM. The genomic DNA G+C content was 67.5–67.9 mol%. Menaquinone MK-9(H4) was the predominant respiratory quinone and meso-diaminopimelic acid was present in the cell-wall peptidoglycan layer. The major cellular fatty acids were C15 : 0 and anteiso-C15 : 0. On the basis of the results obtained in this study, strains BL-34T and BL-35 should be classified within a novel taxon, for which the name Brooklawnia cerclae gen. nov., sp. nov. is proposed. The type strain of Brooklawnia cerclae is BL-34T (=LMG 23248T=NRRL B-41418T). An additional strain, BL-35 (=LMG 23249=NRRL B-41419), was also characterized.