Abstract
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 (NH 4)2SO 4. 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.
Highlights
Biodiesel is defined as a mixture of mono-alkyl esters of long chain fatty acids derived from a renewable lipid feedstock, such as vegetable oil or animal fat
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
42 colonies with the morphology typical of yeast were isolated from 42 soil samples, then42 yeast colonies were tested for lipid accumulation on nitrogen-limiting medium supplemented with 70 g/l glucose and only one isolate namely Y30 was preliminary defined as an oleaginous yeast with lipid content of 22.7% of cellular dry weight (CDW)
Summary
Biodiesel is defined as a mixture of mono-alkyl esters of long chain fatty acids derived from a renewable lipid feedstock, such as vegetable oil or animal fat. Microbial oils and lipid produced from oleaginous microorganisms, are considered as promising feedstock because of their similar fatty acid composition to that of vegetable oils. The culture of these microbe species is affected neither by seasons nor by climates and can accumulate lipids within a short period of time as well as grow well on a variety of substrates (Hassan et al, 1996; Xue et al, 2006; Angerbauer et al, 2008; Li et al, 2008; Meng et al, 2009). The majority of those lipids are triacylglycerol (TAG) that contained long-chain fatty acids that
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