Structural characterization and biological evaluation of Staphylosan (dimannooleate), a new glycolipid surfactant produced by a marine Staphylococcus saprophyticus SBPS-15

Marine microbes have gained significant attention as potential biofactories for broad spectrum bioactive compounds. In the recent years, bioactive biosurfactants have warranted renewed interest from both environmental and clinical sectors as anti-biofilm agents due to their excellent properties of dispersing microbial biofilms. The present study explores a new glycolipid biosurfactant produced by a marine Staphylococcus saprophyticus exhibiting interesting biological activities. This glycolipid biosurfactant was purified and identified as Mannose-Mannose-Oleic acid (named as Staphylosan) based on the results of NMR, GC, GC-MS, MALDI-TOF-MS and tandem MS analysis. The surface tension and critical micelle concentration of purified Staphylosan was 30.9 mN m^-1 and 24 mg L^-1. Further, it showed promising biofilm inhibition and dislodging activities against a panel of profuse biofilm forming bacteria at both single and multi-species level which were isolated from boat hull biofilm environment such as Bacillus subtilis BHKH-7, Acinetobacter beijerinckii BHKH-11, Pseudomonas aeruginosa BHKH-19, Serratia liquefaciens BHKH-23, Marinobacter lipolyticus BHKH-31 and Micrococcus luteus BHKH-39. Moreover, it exhibited anionic charge and revealed non-toxicity towards brine shrimps, suggesting its environmental safety. This is a first report on Staphylosan, a multifunctional glycolipid surfactant from a marine Staphylococcus saprophyticus SBPS-15, exhibiting promising anti-biofilm activities and non-toxic in nature and thus finds possible potential use in many environmental applications especially under marine conditions.