Antagonistic interactions among Antarctic bacteria: phylogenetic and niche-based insights into bacterial communities dynamics

The extreme environments of Antarctica offer unique habitats for microbial life, fostering distinct ecological interactions, including antagonism among bacteria. This study investigates the antagonistic interactions and volatile organic compounds (VOCs) production of psychrotrophic bacterial strains belonging to the genera Pseudoalteromonas and Psychrobacter, isolated from seawater and marine sponges. Antagonism assays revealed that only a small fraction of isolates exhibited significant inhibitory activity, with seawater strains showing a greater antagonistic potential than sponge-associated ones. Inhibition and sensitivity patterns were influenced by both the ecological origin and phylogenetic relatedness of the strains, particularly within the Pseudoalteromonas genus. SPME-GC/MS analyses identified sulfurated compounds such as dimethyl and trimethyl disulfide, along with 2-undecanone, as prominent VOCs produced by the strains. Although antagonistic activity was generally low, VOCs from these strains have demonstrated potential inhibitory effects on pathogens, including multidrug-resistant Staphylococcus spp. and Pseudomonas aeruginosa strains. These findings highlight the ecological and biotechnological relevance of Antarctic bacteria VOCs, shedding light on their potential as bioactive compounds for applications in agriculture and pharmaceutical fields.