title: Biosurfactant production by Pseudomonas aeruginosa A41 using palm oil as carbon source.
abstract: Biosurfactant production by Pseudomonas aeruginosa A41, a strain isolated from seawater in the gulf of Thailand, was examined when grown in defined medium containing 2% vegetable oil or fatty acid as a carbon source in the presence of vitamins, trace elements and 0.4% NH(4)NO(3), at pH 7 and 30 degrees C with 200 rpm-shaking for 7 days. The yield of biosurfactant steadily increased even after a stationary phase. Under such conditions the surface tension of the medium was lowered from 55-70 mN/m to 27.8-30 mN/m with every carbon source tested. However, types of carbon sources were found to affect biosurfactant yield. The yields of rhamnolipid biosurfactant were 6.58 g/L, 2.91 g/L and 2.93 g/L determined as rhamnose content when olive oil, palm oil and coconut oil, respectively, were used as a carbon source. Among them, biosurfactant obtained from palm oil was the best in lowering surface tension of the medium. Increase in biosurfactant activities in terms of oil displacement test and rhamnose content were observed to be higher with shorter chain fatty acids than that of the longer chains (C12>C14>C16). In addition, we found that C18:2, highly unsaturated fatty acid, showed higher oil displacement activity and rhamnose content than that of C18:1. The optimal oil displacement activity was found at pH 7-9 and in the presence of 0.5-3% NaCl. The oil displacement activity was stable to temperatures up to 100 degrees C for 15 h. Surface tension reduction activity was relatively stable at pH 2-12 and 0-5% of NaCl. Emusification activity tested with various types of hydrocarbons and vegetable oils showed similarity of up to 60% stability. The partially purified biosurfactant via TLC and silica gel column chromatography gave three main peaks on HPLC with mass spectra of 527, 272, and 661 m/z respectively, corresponding to sodium-monorhamnodecanoate, hydroxyhexadecanoic acid and an unknown compound, respectively.
authors.affiliation: Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand. jiraporn.Th@chula.ac.th
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Thaniyavarn
authors.forename: Aree
authors.initials: A
authors.lastname: Chongchin
authors.forename: Nopparat
authors.initials: N
authors.lastname: Wanitsuksombut
authors.forename: Suthep
authors.initials: S
authors.lastname: Thaniyavarn
authors.forename: Pairoh
authors.initials: P
authors.lastname: Pinphanichakarn
authors.forename: Natthanant
authors.initials: N
authors.lastname: Leepipatpiboon
authors.forename: Masaaki
authors.initials: M
authors.lastname: Morikawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kanaya
mesh_terms: D006017:Glycolipids / Q000096:biosynthesis*; D000073878:Palm Oil; D010938:Plant Oils / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000378:metabolism*; D013501:Surface-Active Agents / Q000378:metabolism*
chemical_list: D006017:Glycolipids; D010938:Plant Oils; D013501:Surface-Active Agents; C418382:rhamnolipid; D000073878:Palm Oil