Selenomonas lipolytica sp. nov., an obligately anaerobic bacterium possessing lipolytic activity

A novel, oligately anaerobic bacterium capable of hydrolysing lipids was isolated from a tropical anaerobic lagoon receiving waste water from an edible oil mill. The isolate had many characteristics similar to those of members of the genus Selenomonas. The isolate showed lipolytic activity on tributyrin, triolein and groundnut oil in qualitative plate clearance assays, which has not been reported for the type strain of the genus Selenomonas. It did not require n-valerate supplementation for growth on glucose. Acetate and propionate were the only volatile fatty acids produced from glucose fermentation with propionate as the major end product. The isolate could grow optimally at pH 6.8 and at a temperature of 40 degrees C. It could tolerate NaCl concentrations of up to 40 g l-1. The G&C content of the DNA was 40 mol% as determined by thermal denaturation analysis. Comparison of partial 165 rRNA gene sequences revealed that the isolate was most closely related to genus Selenomonas with 91% sequence similarity (250 bp compared) to Selenomonas ruminantium strain GA 192. On the basis of the results obtained in the present investigation, it is suggested that a new species of Selenomonas should be created for this novel isolate and the name Selenomonas lipolytica is proposed for this new species. The type strain is strain CF1BT (= MCMB 505T).