An antimicrobial glycolipid biosurfactant (GBS), extracted and identified from a marine bacterium, was studied to inhibit pathogenic microorganisms. Production of the GBS was optimized using a statistical method, a response surface method (RSM) with a central composite design (CCD) for obtaining maximum yields on a cost-effective substrate, molasses. The GBS-producing bacterium was identified as Buttiauxella Species in terms of biochemical and molecular characteristics. This compound showed a desirable antimicrobial activity against some pathogens such as E. coli, Bacillus subtilis, Bacillus cereus, Candida albicans, Aspergilus niger, Salmonella enterica. The rheological studies described the stability of the GBS at high values in a range of pH (7-8), temperature (20-60) and salinity (0%-3%). The statistical optimization of GBS fermentation was found to be pH 7, temperature 33 °C, Peptone 1%, NaCl 1% and molasses 1%. The potency of the GBS as an effective antimicrobial agent provides evidence for its use against food and human pathogens. Moreover, favorable production of the GBS in the presence of molasses as a cheap substrate and the feasibility of pilot scale fermentation using an RSM method could expand its uses in food, pharmaceutical products and oil industries.
Keywords: Buttiauxella; antimicrobial activity; glycolipid biosurfactant; response surface method.