SHARMA, NIVEDITASHARMA, PUSHPINDER2021-01-182021-01-182021-01https://krishikosh.egranth.ac.in/handle/1/5810160300ABSTRACT Biosurfactant research as well as its development and commercialization have beheld a great significance in recent years. Biosurfactants are considered as amphiphilic surface-active compounds produced by various microbes that harbor numerous unique properties. Oil contaminated sites are highly probable source of oil degrading microorganisms and was utilized as a source for isolation of biosurfactant producing microorganisms. In present study, 40 strains were isolated from biosurfactant producing bacteria from various oil-contaminated sites of Himachal Pradesh. Among them, four strains PS9, PS23, PS26 and PS37 were selected for the further study which were identified as B. tequelensis PS9 |MN 197768|, B. cereus PS23 |197769|, B. subtilis PS26 |197770| and Escherichia fergusoni PS37 |1997771|. Antibacterial and antifungal activity of the strain was also examined. Optimization of culture conditions was done on the basis of various process parameters and medium components viz. media types, temperature, pH, carbon sources, nitrogen sources and media additives firstly using classical One Variable at a Time (OVAT) approach followed by statistical optimization by utilizing Central Composite Design (CCD) of Response Surface Methodology (RSM). Hydrophobicity was found to be maximum at 40°C temp in 1% carbon and nitrogen source in both the strains but at 7.0 and 9.0 pH in B. tequelensis and B. subtilis respectively. Furthermore, 283mg of dried biosurfactant was produced. The extraction and purification was done followed by quantitification of biosurfactant formed by B. tequelensis PS9 which was done by using High Performance Liquid Chromatography (HPLC). The quantity of the biosurfactant came out to be 85.657ppm. Further characterization of purified biosurfactant was done and it was found to be effective at 40°C temperature, 7.0 pH, 1% NaCl concentration and quite stable at 4°C for 9 days while at room temperature upto 5 days. The maximum of 98.25μg/ml protein content was observed. In oildisplacement activity, an impressive zone of 2.6cm was observed and emulsification index was equal to 37.5%. Molecular and structural compositions of the purified biosurfactant were then evaluated by FTIR, NMR and MS/MS and a cyclic lipopeptide {C14 Surfactin (L/I4, D6), [M+H]+ and C15 Surfactin (V4,D6), [M+H]+} by Bacillus tequelensis PS9 were identified. In case of other analytical techniques, FTIR data revealed lactone and peptide form of surfactin, NMR showed glycosidic linkage of sugar moiety and methoxy functional groups indicating the surfactin. The study has a great implication as the biosurfactants are considered safer alternative to synthetic or chemical surfactants as they are less toxic, eco-friendly and of course have low ecological impact. The present study provides further evidence that biosurfactant produced from Bacillus tequelensis PS9 has undoubtedly turned out to be a potential candidate in bioremediation as well as can be recommended for industrial use as a laundry detergentEnglishThesis