Algoriphagus limicola sp. nov., isolated from marine mud: genome-based taxonomy and carotenoid-associated features

A reddish-orange-pigmented bacterium, designated CAU 1675ᵀ, was isolated from marine mud collected at Minmeoru Beach, Ganghwa Island, Republic of Korea, and characterised using a genome-informed polyphasic approach. Cells were aerobic, Gram-stain-negative, non-motile rods, and growth occurred at 20–37°C, pH 6.0–10.0 and 0–3% (w/v) NaCl. Strain CAU 1675ᵀ showed the highest 16S rRNA gene sequence similarity to Algoriphagus ornithinivorans IMSNU 14014ᵀ (96.2%). Phylogenomic analysis based on 92 bacterial core genes placed the strain within the genus Algoriphagus on a distinct lineage. ANIb values between CAU 1675ᵀ and four related type strains were 71.8–72.5%, digital DNA–DNA hybridisation values were 16.7–17.2%, and average amino acid identity values were 76.6–77.8%. The 3.86-Mbp draft genome had a DNA G + C content of 42.3%. Genome mining identified three putative secondary-metabolite biosynthetic gene clusters, including a carotenoid-associated terpene cluster containing crtB, crtI and crtY. Consistent with the reddish-orange colony phenotype, a methanolic cell extract showed a UV–visible absorption maximum at 476 nm, supporting the presence of a carotenoid-type pigment. MK-7 was the predominant respiratory quinone, and iso-C15:0 and summed feature 3 were the major fatty acids. The combined phylogenetic, genomic, phenotypic and chemotaxonomic evidence supports the proposal of Algoriphagus limicola sp. nov., with CAU 1675ᵀ (= KCTC 92739ᵀ = MCCC 1K08476ᵀ) as the type strain.