Microbacter margulisiae gen. nov., sp. nov., a propionigenic bacterium isolated from sediments of an acid rock drainage pond.

ABSTRACT

A novel anaerobic propionigenic bacterium, strain ADRI(T), was isolated from sediment of an acid rock drainage environment (Tinto River, Spain). Cells were small (0.4-0.6×1-1.7 µm), non-motile and non-spore-forming rods. Cells possessed a Gram-negative cell-wall structure and were vancomycin-resistant. Strain ADRI(T) utilized yeast extract and various sugars as substrates and formed propionate, lactate and acetate as major fermentation products. The optimum growth temperature was 30 °C and the optimum pH for growth was pH 6.5, but strain ADRI(T) was able to grow at a pH as low as 3.0. Oxidase, indole formation, and urease and catalase activities were negative. Aesculin and gelatin were hydrolysed. The predominant cellular fatty acids of strain ADRI(T) were anteiso-C15  0 (30.3 %), iso-C15  0 (29.2 %) and iso-C17  0 3-OH (14.9 %). Major menaquinones were MK-8 (52 %) and MK-9 (48 %). The genomic DNA G+C content was 39.9 mol%. Phylogenetically, strain ADRI(T) was affiliated to the family Porphyromonadaceae of the phylum Bacteroidetes. The most closely related cultured species were Paludibacter propionicigenes with 16S rRNA gene sequence similarity of 87.5 % and several species of the genus Dysgonomonas (similarities of 83.5-85.4 % to the type strains). Based on the distinctive ecological, phenotypic and phylogenetic characteristics of strain ADRI(T), a novel genus and species, Microbacter margulisiae gen. nov., sp. nov., is proposed. The type strain is ADRI(T) ( = JCM 19374(T) = DSM 27471(T)).