Proteiniphilum acetatigenes gen. nov., sp. nov., from a UASB reactor treating brewery wastewater

Abstract

Two proteolytic, strictly anaerobic bacterial strains (TB107 T and TB6-6) were isolated from the granule sludge of an upflow anaerobic sludge blanket reactor treating brewery wastewater. The strains were Gram-negative, non-spore-forming and motile. Cells were rod-shaped (0·6–0·9×1·9–2·2 μm). Growth of the strains was observed at 20–45 °C and pH 6·0–9·7. The strains were proteolytic. Yeast extract, peptone, pyruvate, glycine and l-arginine could be used as carbon and energy sources. Weak growth was also observed with tryptone,l-serine,l-threonine and l-alanine as carbon and energy sources. Both strains did not use any of the tested carbohydrates, alcohols and fatty acids except pyruvate. Acetic acid and NH 3 were produced from yeast extract, peptone and l-arginine, and propionic acid was also produced from yeast extract. Pyruvate was converted to acetic acid and CO 2. Gelatin was not hydrolysed. Indole and H 2 S were not produced. The two strains did not grow in medium containing 20 % bile. Addition of strain TB107 T to a syntrophic propionate-degrading co-culture accelerated the propionate-degradation rate. The predominant cellular fatty acid was the branched-chain fatty acid anteiso-C 15 : 0(46·21 %). The genomic DNA G+C contents of strains TB107 T and TB6-6 were 46·6 and 48·9 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains represent a new phyletic sublineage within the Cytophaga–Flavobacterium–Bacteroides(CFB) group, with <91 % 16S rRNA gene sequence similarity to the closest species with validly published names. On the basis of polyphasic evidence from this study, a new genus and species,Proteiniphilum acetatigenes gen. nov., sp. nov., is proposed, with strain TB107 T(=JCM 12891 T=AS 1.5024 T) as the type strain.