This thesis deals with the isolation of a marine biosurfactant producing bacterium followed by evaluation of therapeutic and environmental application potentials of the isolated biosurfactant product. The maximum amount of extracellular biosurfactant was produced in a growth-associated manner using glycerol as a carbon substrate. The biosurfactant product was found to be a lipopeptide and reduced the surface tension of water from 72–28 mN m-1 at a low critical micelle concentration (CMC) of 40 mg l–1. A unique characteristic of the test biosurfactant was the presence of glycine in its hydrophilic peptide moiety. It emulsified hydrocarbons and showed stability at different pH and temperatures. The test biosurfactant also caused micellar entrapment and subsequent increase in bioavailability and utilization of anthracene, a model polyaromatic hydrocarbon. It was able to bind toxic heavy metals through strong ionic interactions. At even half the CMC value, it could remove 76.6 and 42.7% of lead and cadmium respectively, as estimated by Atomic Absorption Spectroscopy. The biosurfactant was found to have an antiadhesive action on microbial films by adhesion inhibition and microbial film disruption in a concentration range from 0.1–10 mg ml–1. This case study was the first report till date on antiadhesive potential of marine biosurfactants. Unlike previously reported lipopeptide biosurfactants, the test biosurfactant was found to be non-hemolytic in nature and can have tremendous implications as a drug candidate, for its very significant antimicrobial action against selected pathogenic strains including a few multi-drug resistant (MDR) strains. In spite of its insignificant antioxidant activity, the biosurfactant demonstrated marked antiproliferative activity on the breast cancer cell line tested with a very low IC50 value of 100 ng ml–1. Apoptosis induced by the product was detected by FACS analysis and the change in nuclear morphology. Thus the important features with which the biosurfactant is endowed will pave the path for the development of new drugs for chemotherapy. Considering scanty information on application potentials of lipopeptide biosurfactants of marine origin, this thesis would surely contribute positively to the scientific literature and open up new avenues in biosurfactant R&D. Keywords Marine Bacillus circulans, surface activity, carbon substrates, HPTLC, non-hemolytic biosurfactant, polyaromatic hydrocarbons, anthracene, bioavailability, biodegradation, metal remediation, micelles, TEM, FTIR, HPLC, antimicrobial activity, MDR strains, MIC, MBC, antiadhesive potential, CLSM, biofilm, cytotoxicity, FACS