Putative biosurfactants from polar microbial consortia

Biosurfactants (BS) are amphiphilic microbial metabolites that are biodegradable, low in toxicity, and environmentally compatible, making them attractive for applications in food, pharmaceutical, and bioremediation industries. This study investigated the phylogenetic composition and biosurfactant-producing potential of marine oil snow (MOS)-associated microbial consortia from the Churchill Marine Observatory, western Hudson Bay. MOS aggregates were cultivated in mineral Bushnell–Haas (BH) medium supplemented with 3% (w/v) NaCl, using motor oil as the sole hydrocarbon source. Enrichment cultures capable of growth in BH medium were subsequently evaluated for biosurfactant production using qualitative and quantitative assays at 4 °C and 20 °C. All cultures were maintained as enrichment consortia throughout the study. A total of eight enrichment cultures were identified as biosurfactant-producing consortia. 16S rRNA gene sequencing revealed that Pseudoalteromonas dominated all consortia, while Paraglaciecola , Marinomonas , and other taxa were present at varying relative abundances. Although none of the consortia exhibited high emulsification activity (E 24 > 40%), biosurfactant yields were significantly higher at 4 °C. Additionally, three consortia tested positive for rhamnolipid-type biosurfactant production.