Clostridium peptidivorans sp. nov., a peptide-fermenting bacterium from an olive mill wastewater treatment digester.

A new peptide-degrading, strictly anaerobic bacterium, designated strain TMC4T, was isolated from an olive mill wastewater treatment digester. Cells of strain TMC4T were motile, rod-shaped (5-10 x 0.6-1.2 microm), stained Gram-positive and formed terminal to subterminal spores that distended the cells. Optimal growth occurred at 37 degrees C and pH 7 in an anaerobic basal medium containing 0.5% Casamino acids. Arginine, lysine, cysteine, methionine, histidine, serine, isoleucine, yeast extract, peptone, Biotrypcase, gelatin and crotonate also supported growth, but not carbohydrates, organic acids or alcohols. The end-products of degradation were: acetate and butyrate from lysine and crotonate; acetate, butyrate, H2 and CO2 from Biotrypcase, gelatin and peptone; acetate, alanine, H2 and CO2 from cysteine; acetate, H2 and CO2 from serine, cysteine and yeast extract; acetate and formate from histidine; propionate from methionine; methyl 2-butyrate, H2 and CO2 from isoleucine; acetate and ethanol from arginine; and acetate, propionate, butyrate, methyl 2-butyrate, H2 and CO2 from Casamino acids. The DNA G+C content of strain TMC4T was 31 mol%. Phylogeny based on 16S rRNA sequence analysis showed that strain TMC4T was a member of the low-G+C-content Gram-positive genus Clostridium, with the closest relative being Clostridium pascui (sequence similarity of 96 %). Due to considerable differences in genomic and phenotypic properties between strain TMC4T and those of its nearest relative, strain TMC4T is proposed as a new species of the genus Clostridium, Clostridium peptidivorans sp. nov. Strain TMC4T has been deposited in the DSMZ as strain DSM 12505T.