PRODUCTION AND CHARACTERIZATION OF A BIOSURFACTANT ISOLATED FROM PSEUDOMONAS-AERUGINOSA UW-1

Pseudomonas aeruginosa UW-1 produced 17-24 g L-1 rhamnolipid in vegeta ble oil-containing media in shake flask cultures in 13 days, In time c ourse studies of growth and rhamnolipid production in a salts medium c ontaining 6% canola ail, total bacterial count reached 2.6 x 10(10) CF U ml(-1) after 48 h and a maximum rhamnolipid yield of 24.3 g L-1 was obtained after 9 days, Rhamnolipid components were purified and separa ted by chloroform-methanol extraction and TLC chromatography. The majo r rhamnolipid components were characterised as amnosyl-beta-hydroxydec anoyl-beta-hydroxydecanoate and amnosyl-beta-hydroxydecanoyl-beta-hydr oxydecanoate by nuclear magnetic resonance and mass spectrometry, The components were separated preparatively by silica gel column chromatog raphy, The recovered monorhamnosyl fraction contained no dirhamnosyl m oiety while the recovered dirhamnosyl fraction contained 5% of the mon orhamnosyl moiety when analyzed by HPLC. The ratio of mono-to dirhamno syl components produced by P, aeruginosa UW-1 was determined by HPLC t o be 4:1 by weight, Purified mono-and dirhamnosyl components had the s ame CMC value of 40 mu g ml(-1) and decreased the surface tension of w ater to 27.7 and 30.4 dynes cm(-1), respectively.