Psychrotrophic Antarctic marine bacteria as potential reservoirs for novel antimicrobial genes

Antarctica is a very cold, isolated continent surrounded by frozen seas, yet these extreme environmental conditions have not restricted life and diversity in the sea. The marine environment is seasonally highly productive and harbours diverse and abundant communities of organisms, with many endemic species occurring nowhere else in the world. Such communities and their associated microbiomes are increasingly recognized as an unexplored source of novel antimicrobial products. Hence, the major aim of this study was to examine the antimicrobial potential of bacteria cultured from eight Antarctic marine invertebrate species, while gathering data on Antarctic microbial thermal and salinity tolerances. All cultured bacterial species (n = 34) were related to known psychrotrophs, with thermal tolerances that far exceeded those of their invertebrate hosts. Of note, two strains of Psychrobacter and Pseudomonas produced antagonistic activity towards epidemic methicillin-resistant Staphylococcus aureus, Micrococcus luteus, and Candida albicans in preliminary simultaneous antagonism screens. Draft whole genome sequence analysis revealed the presence of 13 biosynthetic gene clusters; including those with potential to produce betalactones, post-translationally modified peptide products, and arylpropynes. These results emphasize the need for more extensive and systematic surveys to identify novel biomolecules from Antarctic marine bacteria that may be exploited for societal gain.