Effect of Glycerol as Carbon Source for Biosurfactant Production by Halophilic Bacteria Pseudomonas Stutzeri BK-AB12

Biosurfactant is a surface active agents synthesized by living organism as a secondary metabolites. Biosurfactant can be synthesized by bacteria in the limited condition of nutritions. In this experiment, biosurfactant was synthesized and charaterized from halophilic bacteria isolated from Bledug Kuwu Mud Crater, Pseudomonas stutzeri BK AB-12 with glycerol as carbon source and KNO3 as nitrogen source. The growth medium used was Luria Bertani (LB) and the production medium was Gly-MSM with the additional of 5% salt concentration. Biosurfactant activity was monitored with Oil Spreading Test (OST) method. The glycerol concentration was varied from 2 to 6% to obtain the optimum condition of bacteria in producing biosurfactant. The highest OST result obtained by 3% glycerol concentration after the bacteria were incubated for 28 hours at 37 oC and with the aeration rate of 150 rpm, wherein the resulted oil spreading diameter was about 1.35 cm. Supernatant which contain the biosurfactant gave emulsification index (EI24) 53.33% and worked optimally at pH 12 to 14, 15% NaCl concentration, and temperature until 60 oC. CTAB result gave blue zone on the Blue Plate Agar indicated that the biosurfactant is anionic type. Biosurfactant gave CMC at 48.44 mg/L. FTIR characterization exhibited high similarity of the biosurfactant spectrum to that of rhamnolipid standard.