Abstract:
Isolation of 19 samples collected from various places yield 108 bacterial isolates. Among them it was found that bacterium strain A41 isolation from sea water at Donhoylod, Samuthsongkran province later on classified in the genus Pseudomonas is best biosurfaclant producer. TLC analysis of partially purified products upon cultivation by the use of glucose as C-source revealed 4 components with R1value of 0.33, 0.53, 0.83, and 0.92 respectively. These are found differ from that of standard biosurfaclant from Bacillus subtilis. Result from HPLC and HPLC-MC indicate the compound possesses mass between 573-1494 m/z by which those with mass of 1034, 1322 and 1494 m/z are difference from molecular mass of rhamnolipids from other Pseudomonas spp. Which possesses molecular mass between 334-816. This Pseudomonas sp. A41 gave high yield of biosurfactant upon cultivated by the use of 2% w/v palm oil as carbon source,0.3 % w/v NH₄NO₃ as nitrogen source and 4.3 mg/l ferrous sulfate as essential mineral. Optimum condition for the production of biosurfactant are inoculum age of 15 hrs. at 8% v/v. initial pH of 7.0 , 200 rpm. Room temperature (30+20°C) for 30 hrs. The biosurfactant yielded could lower surface tension down to 29 mN/m with CMC value of 240 mg./l which is lower than that of SDS, a chemical surface active agent. The product is stable at pH 2-10 and temperature of 60 and 100℃ for 5 hrs. that could still lower suface tension when present in 25% w/v sodium chloride solution and form emulsion with number of hydrocarbon compounds such as hexadecane, cyclohexane, benzene, kerosene and paraffin oil.