ABSTRACT
Surfactants are surface active molecules which play an important role in variousindustrial processes and product formation due to their interfacial properties, biodegradabilityand eco-friendly nature. Many of the chemical surfactants in use today are produced fromnon-renewable petrochemical feedstocks, hence bio surfactants produced by microorganismsusing renewable and cheap substrates are considered as viable alternatives to petroleumbased surfactants. In the current study, the optimization of various parameters for maximumproduction of bio surfactant, by Serratia rubidaea KAP isolated from oil contaminated soilsample, was carried out. Optimum bio surfactant production was obtained in a mediumcontaining; (g %) KH2PO4 (0.3), Na2HPO4 (0.6), yeast extract (0.5), NaCl (0.5), (NH4)2SO4 (0.3),MgSO4.7H2O (2mg), FeSO4.7H2O (0.002), and CaCl2.2H2O (0.006), rice bran oil (5% v/v) with C:N and C: P ratio as 8:1 and 7:1 respectively. The media was adjusted to pH 7.2, inoculated with5% v/v test culture prepared at 0.8O.D600nm, and incubated at 30°C for 96h under agitationspeed of 160rpm. The resulting bio surfactant yield of 1.0g% was achieved, with 0.88g% weightof dry biomass, 56.78% decrease in surface tension of the medium and emulsification index of87.5%. Thus the isolate showed good potential as a bio surfactant-producing bacterium thatcan be used for large scale production using rice bran oil as a cost-effective substrate, as analternative to chemical surfactants.