The genus Psychromonas includes psychrophilic or psychrotolerant bacteria frequently isolated from cold marine environments, such as polar regions, the deep sea and cold currents, however, its taxonomic diversity associated with marine macroalgae remains underexplored. A taxonomic study was conducted on strain PT13T, which was isolated from the tissue of marine macroalga Saccharina japonica collected from a kelp farming area in Putian, China. The isolate was characterized as Gram-stain-negative, short-rod-shaped, non-pigmented, and motile by means of polar flagella. Growth occurred in the presence of 2-4.5% (w/v) NaCl (optimum, 4%) and at 4-35℃ (optimum, 25℃). Phylogenetic analysis based on the full-length 16 S rRNA gene sequence revealed that the closest relatives were Psychromonas heitensis AK15-027T (97.5% sequence similarity) and Psychromonas agarivorans J42-3AT (97.0%). Average nucleotide identity (ANI) values with other species with other validly published species of the genus were all below 95.0%. The predominant cellular fatty acids were C16:1ω7c/C16:1ω6c, followed by C16:0. The genomic DNA G + C content was determined to be 37.8%. Genome analyses revealed an ability to utilize the components of Saccharina japonica tissue via secreted enzymes. The genome analyses of PT13T contained genes for alginate lyase and fucosidase, and it possesses both Type II and Sec-SRP secretion systems. Based on phenotypic, chemotaxonomic, genomic, and phylogenetic data, strain PT13T represents a novel species of the genus Psychromonas, for which the name Psychromonas saccharinae sp. nov. is proposed. The type strain is PT13T (= JCM 38121T = MCCC 1K09960T).
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