Diversity of culturable actinobacteria associated with deepwater endemic amphipods of Lake Baikal and study of their biosynthetic capabilities

Lake Baikal’s ecosystem is among the oldest lacustrine ecosystems on the planet with a diverse and unique flora and fauna. Amphipods (Amphipoda, Crustacea) are one of the most diverse groups among the lake’s invertebrate animals. The lake contains more than 350 species and subspecies of amphipods, and each of these species play a significant role in the lake’s food webs. However, their relationships with microorganisms are poorly investigated, which leaves gaps in understanding the relations between aquatic crustaceans and bacteria. We studied the diversity of a specific group of culturable microorganisms (Actinobacteria), and their possible relations with deepwater endemic amphipods present in Lake Baikal. We found that while 73% of the isolated strains belong to the widely distributed genus of Streptomyces , 27% of the isolates belong to rare genera such as Amycolatopsis , Micromonospora , and Pseudonocardia . Fifty-three percent of the studied strains expressed antibiotic activity against Gram-positive bacteria and possess polyketide synthase (PKS) genes. Thus, Actinobacteria associated with Baikal’s endemic deepwater amphipods might both protect amphipods against pathogenic microorganisms and be an untapped source of new natural products with biosynthetic potential.