Biodiversity and Metabolic Properties of Bacterial Communities from the Digestive System of the Bivalve Crenomytilus grayanus

Abstract — Biodiversity of the bacterial communities in the digestive system of Crenomytilus grayanus inhabiting the coastal Sea of Japan waters with chronic anthropogenic pollution was investigated using metabarcoding. Apart from marine bacteria, the taxa typical under contamination with oil ( Rhodobacteraceae , Corynebacteriaceae ), heavy metals ( Asinibacterium ), and unprocessed municipal waste ( Cloacibacterium, Globicatella ) were revealed in the microbiota. A collection of 411 cultured heterotrophic bacterial strains isolated in the course of this study was characterized taxonomically. The intestinal microbiome of the studied mollusks was shown to have a unique composition, depending on their habitat. Ability of bacterial strains isolated from the C. grayanus digestive system to degrade various nutrient substrates (sugars, amino acids, and polysaccharides) and xenobiotics (oil hydrocarbons, bisphenol A, and atrazine) was studied. Most isolates degraded a broad range of organic substrates; 13% (54 strains) oxidized oil hydrocarbons; 1% (4 strains) oxidized bisphenol A; and 0.5% (2 strains) degraded atrazine. The possible role of the microbiome C. grayanus microbiome in symbiotic digestion and in detoxication of the mollusk is discussed.