Abstract:
Oleaginous yeast, Pseudozyma tsukubaensis YWT7-2, was screened from 28 yeast strains isolated from mangrove forests in Chantaburi province. It had oil content 31.36% w/w, (dry cell weight). This is the first report of P. tsukubaensis YWT7-2 as oleaginous yeast. The P. tsukubaensis YWT7-2 produced oil when grown in both high carbon/ nitrogen medium and glucose solution. This indicated that cell propagation and oil production of the P. tsukubaensis YWT7-2 were temporally separated. However, maximum oil yield in the high carbon/nitrogen medium was higher than glucose solution. Oil content and cell biomass of the P. tsukubaensis YWT7-2 grown in cassava starch hydrolysate treated with Ca(OH)2 (DCSH) were higher than cassava starch hydrolysate (CSH). Maximum oil yield in the DCSH was 1.49 g/l (oil productivity 0.75 g/l/d) in the DCSH. Addition of 0.25% (w/v) (NH4)2SO4 into the DCSH increased the maximum oil yield to 3.85 g/l (oil productivity 1.28 g/l/d). Optimal pH for oil production was 5.5. Propagation of cell inoculum in DCSH containing 0.2% (w/v) (NH4)2SO4 and 0.1% (w/v) KH2PO4 instead of CSH containing 0.2% (w/v) (NH4)2SO4 increased the maximum oil yield to 5.42 g/l (oil productivity 1.36 g/l/d). Oil of P. tsukubaensis YWT7-2 produced in the high carbon/nitrogen medium and DCSH had similar major fatty acids composition ; palmitic acid, oleic acid, linoleic acid and stearic acid. The P. tsukubaensis YWT7-2 oil was suitable as raw material for biodiesel production.