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

Summary auto-generated

Researchers isolated and characterized a novel obligately anaerobic bacterium designated Selenomonas lipolytica sp. nov. from a tropical anaerobic lagoon receiving waste water from an edible oil mill. The strain CF1BT exhibits strong lipolytic activity, hydrolyzing tributyrin, triolein, and groundnut oil—a characteristic not previously documented for Selenomonas species. The bacterium is a Gram-negative, curved rod measuring 0.55–0.77 by 3.3–4.5 μm with 4–5 flagella arranged as a tuft near the concave side. Growth occurs optimally at 40°C and pH 6.8, with tolerance to NaCl up to 40 g/L. Glucose fermentation produces acetate and propionate as end products, with propionate being the major product. Unlike other Selenomonas species, strain CF1BT does not require n-valerate supplementation for growth. The DNA G+C content is 40 mol%. Phylogenetic analysis using partial 16S rRNA gene sequences shows 91% similarity to Selenomonas ruminantium strain GA 192, with the isolate forming a distinct phylogenetic cluster within the Selenomonas genus. The discovery of lipolytic activity in this obligate anaerobe has potential applications in anaerobic waste treatment and lipase production without aeration costs.

Key findings

Selenomonas lipolytica is a novel obligately anaerobic bacterium possessing true lipolytic activity on tributyrin, triolein, and groundnut oil, a trait not previously reported for the Selenomonas genus
The strain does not require n-valerate supplementation for glucose utilization, distinguishing it from related Selenomonas species like S. ruminantium
Phylogenetic analysis based on 16S rRNA gene sequences shows 91% similarity to S. ruminantium GA 192 but forms a distinct cluster, supporting its classification as a new species
Optimal growth occurs at 40°C and pH 6.8, with DNA G+C content of 40 mol%, and the organism produces acetate and propionate as primary fermentation end products
The obligate anaerobe's lipolytic capability offers potential biotechnological applications for lipase production and lipid degradation in anaerobic waste treatment systems without aeration costs

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Abstract

A novel, obligately 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 °C. It could tolerate NaCI 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 16S 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 CF1B^T(= MCMB 505^T).