Isolation and Characterization of Pseudooceanicola aestuariicola sp. nov., from Tidal-Flat Sediments.

A novel bacterial strain, designated MF1-13ᵀ, was isolated from tidal-flat sediment collected in Gochang, Republic of Korea. Cells of strain MF1-13ᵀ are Gram-stain-negative, facultatively anaerobic, motile, and short rod-shaped to ovoid, forming pale yellow colonies on marine agar. The strain produces catalase and oxidase. It grows at 25-30 °C (optimum, 30 °C), at pH 6-8.0 (optimum, pH 7.0), and in the presence of 0-5% (w/v) NaCl, with optimal growth at 2% (w/v). Phylogenetic analysis based on 16 S rRNA and genome sequences placed strain MF1-13ᵀ within the family Roseobacteraceae (class Alphaproteobacteria), showing highest sequence similarity to Pseudooceanicola nitratireducens JLT1210ᵀ (97.2%), Pseudooceanicola onchidii XY-99ᵀ (96.8%) and Pseudooceanicola flagellatus DY470ᵀ (97.2%). The major polar lipids are phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. The genome of strain MF1-13ᵀ is 4.24 Mbp in size, with a G + C content of 61.2%. The strain hydrolyzes starch, gelatin, and Tween 20, 40, and 80, but do not hydrolyze casein or DNase. The predominant cellular fatty acids are C16:0, C18:1 ω7c 11-methyl, and Summed Feature 8 (C18:1 ω7c/C18:1 ω6c). Genomic comparisons (ANI, AAI, and dDDH) between strain MF1-13ᵀ and related taxa were well below species delineation thresholds, supporting its classification as a novel species. Based on polyphasic taxonomic analysis, strain MF1-13ᴛ represents a novel species of the genus Pseudooceanicola, for which the name Pseudooceanicola aestuariicola sp. nov. is proposed. The type strain is MF1-13ᵀ (= KEMB 21563ᵀ = KCTC 8775ᵀ = JCM 37675ᵀ).