Isolation of Biosurfactant Producing Bacteria from the Deep-Sea Sediment
Takafumi KOJIMA*a, Yoshihiro TAKAKIb, Akira INOUEb, Ron USAMIa, and Koki HORIKOSHIa,b
a Department of Applied Chemistry, Faculty of Engineering, Toyo University, 2100 Kujirai, Kawagoe 350, Japan
b The DEEPSTAR Group, Japan Marine Science and Technology Center, 2-15 Natsushima- cho, Yokosuka 237, Japan
Many synthetic surface active agents are used in various fields of industry. It has been a serious problem that large amounts can influence ecosystems, so now a safer and more biodegradable surfactant is needed. Some microorganisms are known to produce surface active agents, referred to as a biosurfactant (BS), which are classified as lipopeptides, glycolipids, phospholipids and polymeric biosurfactants (1). It is now expected that BSs will have higher levels of biodegradation and safety than synthetic surfactants. Most of these organisms have even been isolated from land, but isolation has not been tried from the deep-sea, where organismsare specialized to live at high pressures, low temperatures and high saltiness. So, we tried to isolate BS producing bacteria from deep-sea mud samples collected from Suruga Bay, Sagami Bay, Ogasawara, Nihon Trench, Palau Trench, Yap Trench and Mariana Trench using "SHINKAI 2000", "SHINKAI 6500" and "KAIKO". In order to isolate selectively BS producing bacteria, mud samples were treated with organic solvents in a preculture step, and their isolates were confirmed to have the ability to produce BS with oil film breaking and oil emulsification properties.
Many isolates were obtained from all areas sampled the organic solvent pre- treatment gone better results than direct culturing. The strain BSK34, identified as Bacillus genus, produced BS at thirty two times the critical micelie concentration. The purified BS lowered the surface tension of water from 72 mN/m to 27 mN/m and emulsified petroleum in sea-water. BS produced from BSK63 had antibacterial activity to Bacillus subtilis. In their structural analysis, both BSs from BSK34 and BSK63 were characterized as lipopeptides. A hydrophobic part of both agents contained mainly saturated and 3-hydroxy fatty acids. On the other hand, the hydrophilic part in BSK34 contained four kinds of amino acids, leucine, valine, aspartic acid and proline, while in BSK63, leucine, isoleucine, aspartic acid and glutamic acid were identified. The BS from BSK63 had the same character as the surfactin produced by Bacillus subtilis ATCC 21332 (2), but the amino and fatty acids compositions were different.
We are proceeding with detail structural analysis and characterization of BSs.
1. Desai, J.D. and Banat, I.M. (1997) Microbiol. Mol. Biol. Rev., 61. (1) 47-64.
2. Arima, K., Kakinuma, A., and Tamura, G. (1968) Biochem. Biophys. Res. Commun., 31,488- 494.
