Kinetic growth of the isolated oleaginous yeast for microbial lipid production

Microbial lipid was produced by the soil isolated oleaginous yeast Torulaspora maleeae Y30 using glucose in flask-batch fermentation. At low concentration of nitrogen, maximum lipid production rate was observed; while high nitrogen concentration (0.4 g/l) resulted in high volumetric cell mass production rate (0.960 g/l d) and specific growth rate (0.266 d-1). The isolated yeast T. maleeae Y30 had maximum values of 0.382 g/l d, 0.507 g lipid/g cells, 3.06 g/l and 0.105 g/L d for volumetric lipid production rate, specific yield of lipid, lipid concentration and specific rate of lipid production, respectively when culture was performed in nitrogen-limiting medium supplemented with 90 g/l glucose and 0.2 g/l (NH4)2SO4. The Monod’s constant (KS, g/l) and μmax (1/d) of 24.52 and 0.156, were obtained, respectively. The three major constituent fatty acids of the isolated yeast T. maleeae Y30 were palmitic acid, stearic acid and oleic acid that are comparable to vegetable oils, suggesting that, microbial lipid from these yeast can be used as potential feedstock for biodiesel  production.Key words: Microbial lipid, oleaginous yeast, Torulaspora maleeae Y30, biodiesel

Heterotrophic Microorganisms: A Promising Source for Biodiesel Production

The authors discuss occurrence of heterotrophic microbes, specifically bacteria, yeast, and molds, in biodiesel production is well discussed. Besides, these oleaginous microorganisms are reported to accumulate triacylglycerols (TAGs) that contain long-chain fatty acids. Most of the evidence suggests that TAGs accumulated are suitable for biodiesel production. Lipid accumulation (de novo or ex novo) required a set of enzymes and expression of various genes that are under complex regulatory system. The authors take a step in this direction and provides a summary of the actual knowledge on heterotrophic oleaginous species, their fatty acids, TAGs, and sterol biosynthesis with a biochemical and genetic approaches to better understand their regulation. Likewise, the impact of abiotic factors that can contribute to higher lipid accumulation is summarized. This review also highlights various issues concerning genetic engineering that may contribute to an advanced path forward for microbial feedstock-based biodiesel