Saccharofermentans acetigenes gen. nov., sp. nov., an anaerobic bacterium isolated from sludge treating brewery wastewater

Abstract

A spore-forming anaerobic bacterium, designated strain P6T, was isolated from the sludge of an up-flow anaerobic sludge blanket reactor treating brewery wastewater. Cells were Gram-positive, oval and 0.6–0.9 μm by 1.2–1.8 μm in size. Growth was observed at 20–42 °C and at pH 5.0–7.5. It fermented several hexoses, polysaccharides and alcohols. Sucrose and aesculin could also be fermented. The main end products of fermentation from glucose were acetate, lactate and fumarate; trace CO2 and H2 were also produced. The DNA G+C content of strain P6T was 55.6 mol%. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C14 : 0 3-OH. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain P6T represented a novel phyletic sublineage in clostridial cluster III, and showed <91 % similarity to the type strains of recognized species in this cluster. Phenotypically, the new isolate was distinguished from its phylogenetic relatives (e.g. Clostridium straminisolvens, Clostridium thermocellum, Acetivibrio cellulolyticus and Clostridium aldrichii) by producing acid from glucose and its inability to degrade cellulose. On the basis of evidence from this polyphasic study, strain P6T is considered to represent a novel species of a new genus, for which the name Saccharofermentans acetigenes gen. nov., sp. nov. is proposed. The type strain of Saccharofermentans acetigenes is P6T (=JCM 14006T =AS 1.5064T).