Bacillus nitroreducens sp. nov., a humus-reducing bacterium isolated from a compost

Area of Science:

• Microbiology
• Bacteriology
• Environmental Science

Background:

• Compost environments harbor diverse microbial communities.
• Characterization of novel bacterial species is crucial for understanding microbial ecology and potential applications.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from a compost pile.
• To determine the taxonomic and phylogenetic placement of the isolate using a polyphasic approach.

Main Methods:

• Isolation and cultivation of strain GSS08(T) from compost.
• Phenotypic characterization including growth conditions (NaCl, pH, temperature) and anaerobic respiration.
• Chemotaxonomic analysis (respiratory quinone, polar lipids, fatty acids) and genotypic analysis (DNA G+C content, 16S rRNA gene sequencing, DNA-DNA hybridization).

Main Results:

• Strain GSS08(T) is a Gram-positive, facultative anaerobic, motile rod with optimal growth at 37°C, pH 7.5, and 1% NaCl.
• Anaerobic growth occurs with specific electron acceptors, and chemotaxonomic analyses reveal MK-7, diphosphatidylglycerol, and phosphatidylethanolamine as key components.
• Phylogenetic analysis shows 97.5% 16S rRNA gene similarity to Bacillus humi, but DNA-DNA relatedness of 50.8% confirms its status as a distinct species.
• DNA G+C content is 39.6 mol% with major fatty acids iso-C15:0, anteiso-C15:0, and iso-C16:0.

Conclusions:

• Strain GSS08(T) represents a novel species within the genus Bacillus.
• The proposed name for this new species is Bacillus nitroreducens sp. nov.
• This finding expands the known diversity of bacteria in compost ecosystems.