Presence of Ecophysiologically Diverse Populations within Cobetia marina Strains Isolated from Marine Invertebrate, Algae and the Environments

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Over the last decade, taxonomic surveys have recovered sixteen strains of Halomonas-like marine heterotrophic bacteria from different ecological habitats. The sixteen strains were isolated from three N.W. Pacific Ocean habitats: seawater, the mussel Crenomytilus grayanus and the degraded thallus of brown alga Fucus evanescens. These strains were subjected to a taxonomic investigation of their phenotypic/physiological, genetic, and phylogenetic features. Analysis indicates these bacteria belong to Cobetia marina. The study found all strains tolerated CdCl₂ concentrations up to 875 mM. Taxonomically, the sixteen strains belong to the same species, nevertheless, their physiological features revealed distinguishing characteristics. For instance, strain KMM 296, recovered from the mussel Crenomytilus grayanus, was distinct from other C. marina strains by its ability to produce highly active alkaline phosphatase. The majority of C. marina strains that were isolated from degraded alga thallus appeared to have a particular metabolic specialisation by utilizing a range of easily assimilable monosaccharides. Notably, despite a high level of genetic similarity (80% of DNA relatedness), the phenotypic features of the strains isolated from degraded alga thallus differed with the type strain C. marina LMG 2217^T. These differences suggest an ecologically adapted population of C. marina at a subspecies level.