Isolation of biosurfactant-producing marine bacteria </A>

Isolation of biosurfactant-producing marine bacteria

Suppasil Maneerat, D. of Industrial Biotech., F. of Agro-Industry, PSU.
Janjira Isaram, D. of Industrial Biotech., F. of Agro-Industry, PSU.
Ryo Ishimoto, Research Institute of Bioresources, Okayama U., Japan
Aran H-Kittikun, Asst. Prof., D. of Industrial Biotech., F. of Agro-Industry, PSU.
Fusako Kawai, Research Institute of Bioresources, Okayama U., Japan
Corresponding e-mail : haran@ratree.psu.ac.th

Presented : The 2nd JSPS-NRCT Joint Seminar on Development of Thermotolerant Microbial Resources and their Applications, 21-25 November 2000 Yamaguchi, Japan
Key words : biosurfactant, marine bacteria

Oil spill is one of problems found in many countries located on the coast. These oils normally are degraded showly and cause a severe pollution. To solve the problem, synthetic surfactant is ano-ther means to emulsify these oils. However, this chemicals can be toxic to environment. Therefore, a non-toxic and environmental friendly surfactant should be taken into consideration. Biosurfactants are microbially produced compounds which exhibit surface activity. Biosurfactants are amphiphilic molecules consisting of hydrophobic and hydrophilic domains. Due to their amphipathic nature, bio-surfactants can partition preferentially at the interfaces.

Sea water was collected from harbours and docks in Songkhla, Phuket, Trang and Pattani. The 200 colonies were picked from nutrient agar containing 3% NaCl and heamolytic activity was tested. Twenty-three strains with heamolytic activity were tested for emulsification activity. P6 (2), P3, PA4 (1) and PA6 were able to emulsify weathered crude oil. Among strains tested, P6 showed a most rapid emulsification rate. Therefore, biosurfactant produced from PA6 was subjected to compositional analysis by thin-layer chromatography. A mixture of chloroform, diisopropyl ether, acetic acid and water (60 : 30 : 1; v/v/v/v) was found to be the best solvent for separation. Two bands with Rf of 0.138 and 0.325 were observed when detected by ultraviolet light and iodine vapour, respectively. However, the bands were not developed by ninhydrin and anisaldehyde. This result indicates that biosurfactant is not either protein or carbohydrate.

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