Brooklawnia propionicigenes sp. nov., a facultatively anaerobic, propionate-producing bacterium isolated from a methanogenic reactor treating waste from cattle farms.

Facultatively anaerobic bacterial strains were isolated from samples of a methanogenic reactor and, based on 16S rRNA gene sequences, found to be affiliated with the family Propionibacteriaceae in the phylum Actinomycetota. Four strains with almost-identical 16S rRNA gene sequences were comprehensively characterized. The most closely related species to the strains was Brooklawnia cerclae BL-34T (96.4 % sequence similarity). Although most of the phenotypic characteristics of the four strains were identical, distinct differences in some cellular and physiological properties were also detected. Cells of the strains were Gram-stain-positive, non-spore-forming, pleomorphic rods. The strains utilized carbohydrates and organic acids. The strains produced acetate, propionate and lactate from glucose, but the molar ratios of the products were variable depending on the strains. The strains grew at 10-40 °C (optimum at 35 °C) and pH 5.3-8.8 (optimum at pH 6.8-7.5.) The major cellular fatty acids of the strains were anteiso-C15 : 0, C15 : 0 and C15 : 0 dimethylacetal (as a summed feature). The major respiratory quinone was menaquinone MK-9(H4) and the diagnostic diamino acid in the peptidoglycan was meso-diaminopimelic acid. The genome size of the type strain (SH051T) was 3.21 Mb and the genome DNA G+C content was 65.7 mol%. Genes responsible for propionate production through the Wood-Werkman pathway were detected in the genome of strain SH051T. Based on the results of phylogenetic, genomic and phenotypic analyses of the novel strains, the name Brooklawnia propionicigenes sp. nov. is proposed to accommodate the four strains. The type strain of the novel species is SH051T (=NBRC 116195T=DSM 116141T).

Propioniciclava tarda gen. nov., sp. nov., isolated from a methanogenic reactor treating waste from cattle farms.

Two facultatively anaerobic bacterial strains, designated WR061(T) and WR054, were isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. The two strains were phylogenetically positioned close to one another and had almost the same phenotypic properties. Cells were Gram-reaction-positive, non-motile, non-spore-forming, irregular rods. Cobalamin (vitamin B12) was required for growth. The strains utilized various carbohydrates, including hexoses and disaccharides, and produced acetate and propionate from these carbohydrates. Pentoses and polysaccharides were not utilized. They grew at 20-37 °C (optimum 35 °C) and pH 5.3-8.0 (optimum pH 6.8-7.5). Catalase and nitrate-reducing activities were detected. Aesculin was hydrolysed. The major cellular fatty acids were anteiso-C15:0 and C15:0 DMA, the major respiratory quinone was menaquinone MK-9(H4) and the genomic DNA G+C content was 69.3-69.5  mol%. The diagnostic diamino acid in the peptidoglycan was meso-diaminopimelic acid. Phylogenetic analysis based on 16S rRNA gene sequences placed the strains in the phylum Actinobacteria. Both strains were remotely related to the species in the family Propionibacteriaceae and Propionibacterium propionicum JCM 5830(T) was the most closely related type strain with a sequence similarity of 91.6 %. Based on phylogenetic, physiological and chemotaxonomic analyses, the two novel strains together represent a novel species of a new genus, for which the name Propioniciclava tarda gen. nov., sp. nov. is proposed. The type strain is WR061(T) ( = JCM 15804(T)  = DSM 22130(T)).