Deep sea coral parrot fish mucus: A novel reservoir of marine biosurfactant

Biosurfactants are eco-friendly surface-active biomolecules with significant industrial and biomedical applications. Marine host-associated microhabitats remain largely unexplored for novel biosurfactant-producing microorganisms. Parrot fish mucus, which serves as a protective barrier, harbors a diverse microbial community with unique metabolic capabilities, making it a promising source for bioprospecting. In this study, bacteria were isolated from parrot fish mucus and screened for biosurfactant production. A total of eleven isolates were obtained and subjected to a three-stage evaluation process. Primary screening involved oil displacement and hemolytic assays, followed by secondary screening using emulsification index (E24) and surface tension reduction tests. Several isolates exhibited notable biosurfactant activity. One potent strain demonstrated superior performance, showing significant oil displacement, high emulsification activity, marked hemolysis, and effective surface tension reduction. The selected isolate was further assessed for stability under varying pH, temperature, and salinity conditions. The biosurfactant retained considerable activity across a broad range of environmental parameters, indicating strong stability and suitability for marine applications. Preliminary characterization suggested the presence of amphiphilic compounds, likely glycolipids or lipopeptides. These findings highlight parrot fish mucus as a valuable niche for sustainable biosurfactant-producing bacteria with potential applications in bioremediation, pharmaceuticals, and marine biotechnology.