Flavobacterium okayamense sp. nov. isolated from surface seawater

Area of Science:

• Microbiology
• Bacteriology
• Marine Biology

Background:

• The genus Flavobacterium comprises diverse Gram-negative bacteria found in various environments.
• Identification and characterization of novel bacterial species are crucial for understanding microbial ecosystems and their functions.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from surface seawater.
• To determine the phylogenetic and genomic relatedness of the novel isolate to known Flavobacterium species.
• To formally propose a new species within the genus Flavobacterium.

Main Methods:

• Isolation of bacteria from surface seawater samples.
• Phylogenetic analysis using 16S rRNA gene sequencing.
• Whole-genome shotgun sequencing for average nucleotide identity (ANI) and in silico DNA-DNA hybridization (dDDH) calculations.
• Analysis of cellular fatty acid composition and DNA G+C content.

Main Results:

• A Gram-stain negative, yellow colony-forming bacterium, strain KK2020170 T, was isolated from Kojima Bay, Japan.
• Phylogenetic analysis indicated strain KK2020170 T belongs to the genus Flavobacterium, with F. haoranii LQY-7 T as its closest relative (98.1% 16S rRNA gene similarity).
• Genomic analysis revealed ANI (81.3%) and dDDH (24.6%) values below thresholds for species delineation, supporting its novelty. Key fatty acids included iso-C15:0, iso-C17:0 3-OH, and iso-C15:1 G, with menaquinone MK-6 as the dominant respiratory quinone. DNA G+C content was 31.1 mol%.

Conclusions:

• Strain KK2020170 T represents a novel species within the genus Flavobacterium.
• The proposed name for this new species is Flavobacterium okayamense sp. nov.
• The type strain is KK2020170 T (ATCC TSD-280 T = NBRC 115344 T).