Microbacterium mitrae sp. nov., isolated from salted turban shell.

Area of Science:

• Microbiology
• Bacteriology
• Food Science

Background:

• Microbacterium species are known for their presence in diverse environments, including fermented foods.
• Salted turban shell is a traditional Korean fermented food product.

Purpose of the Study:

• To isolate and characterize a novel bacterium from salted turban shell.
• To determine the taxonomic position of the novel isolate within the genus Microbacterium.

Main Methods:

• Morphological, physiological, and biochemical characterization of the bacterial strain.
• 16S rRNA gene sequencing for phylogenetic analysis.
• DNA-DNA hybridization and chemotaxonomic analysis for species delineation.

Main Results:

• A novel Gram-positive, non-motile, non-spore-forming rod, designated strain M4-8(T), was isolated.
• The strain exhibited yellow-pigmented colonies and tolerance to 0-8% NaCl, with optimal growth at 1% NaCl and 30°C.
• Phylogenetic analysis showed 97.8% 16S rRNA gene similarity to Microbacterium hominis, but low DNA-DNA relatedness (<29%) confirmed it as a new species.
• Major fatty acids were iso-C15:0 and anteiso-C15:0; ornithine was the major cell-wall diamino acid.

Conclusions:

• Strain M4-8(T) represents a novel species within the genus Microbacterium, proposed as Microbacterium mitrae sp. nov.
• The unique characteristics and low DNA-DNA relatedness support its classification as a distinct species.
• This finding expands the known diversity of Microbacterium in fermented food ecosystems.