Rhodoalgimonas zhirmunskyi gen. nov., sp. nov., a Marine Alphaproteobacterium Isolated from the Pacific Red Alga Ahnfeltia tobuchiensis: Phenotypic Characterization and Pan-Genome Analysis

A novel Gram-staining negative, strictly aerobic, rod-shaped, and non-motile bacterium, designated strain 10Alg 79(T), was isolated from the red alga Ahnfeltia tobuchiensis. A phylogenetic analysis based on 16S rRNA gene sequences placed the novel strain within the family Roseobacteraceae, class Alphaproteobacteria, phylum Pseudomonadota, where the nearest neighbor was Shimia sediminis ZQ172(T) (97.33% of identity). However, a phylogenomic study clearly showed that strain 10Alg 79(T) forms a distinct evolutionary lineage at the genus level within the family Roseobacteraceae combining with strains Aquicoccus porphyridii L1 8-17(T), Marimonas arenosa KCTC 52189(T), and Lentibacter algarum DSM 24677(T). The ANI, AAI, and dDDH values between them were 75.63–78.15%, 67.41–73.08%, and 18.8–19.8%, respectively. The genome comprises 3,754,741 bp with a DNA GC content of 62.1 mol%. The prevalent fatty acids of strain 10Alg 79(T) were C(18:1 ω7c) and C(16:0). The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, an unidentified phospholipid and an unidentified lipid. A pan-genome analysis showed that the unique part of the 10Alg 79(T) genome consists of 13 genus-specific clusters and 413 singletons. The annotated singletons were more often related to transport protein systems, transcriptional regulators, and enzymes. A functional annotation of the draft genome sequence revealed that this bacterium could be a source of a new phosphorylase, which may be used for phosphoglycoside synthesis. A combination of the genotypic and phenotypic data showed that the bacterial isolate represents a novel species and a novel genus, for which the name Rhodoalgimonas zhirmunskyi gen. nov., sp. nov. is proposed. The type strain is 10Alg 79(T) (=KCTC 72611(T) = KMM 6723(T)).