Abstract
Co-fermentation of glucose, xylose and l-arabinose from lignocellulosic biomass by an oleaginous yeast is anticipated as a method for biodiesel production. However, most yeasts ferment glucose first before consuming pentoses, due to glucose repression. This preferential utilization results in delayed fermentation time and lower productivity. Therefore, co-fermentation of lignocellulosic sugars could achieve cost-effective conversion of lignocellulosic biomass to microbial lipid. Comprehensive screening of oleaginous yeasts capable of simultaneously utilizing glucose, xylose, and l-arabinose was performed by measuring the concentration of sugars remaining in the medium and of lipids accumulated in the cells. We found that of 1189 strains tested, 12 had the ability to co-ferment the sugars. The basidiomycete yeast Pseudozyma hubeiensis IPM1-10, which had the highest sugars consumption rate of 94.1 %, was selected by culturing in a batch culture with the mixed-sugar medium. The strain showed (1) simultaneous utilization of all three sugars, and (2) high lipid-accumulating ability. This study suggests that P. hubeiensis IPM1-10 is a promising candidate for second-generation biodiesel production from hydrolysate of lignocellulosic biomass.
Highlights
The lipid produced by microorganisms is considered to have powerful potential for the development of a new kind of energy, and has received significant interest from sustainable energy researchers
Lipid accumulated by oleaginous yeast is viewed as a promising alternative to second-generation biodiesel, since the composition of the fatty acids produced by yeast is suitable for biodiesel production
Second-generation biodiesel is made from non-food sources such as rice straw, wood residue, corncob, and sugarcane bagasse. Lignocellulosic hydrolysates from these feedstocks are composed mainly of glucose, xylose, and l-arabinose (Huang et al 2009; Kumar et al 2009; Madhavan et al 2012; Roberto et al 1995; Tsigie et al 2011)
Summary
The lipid produced by microorganisms is considered to have powerful potential for the development of a new kind of energy, and has received significant interest from sustainable energy researchers. Lipid accumulated by oleaginous yeast is viewed as a promising alternative to second-generation biodiesel, since the composition of the fatty acids produced by yeast is suitable for biodiesel production That is, it contains palmitic (16:0), stearic (18:0), oleic (18:1), and linoleic (18:2) acids at a high ratio, mainly in the form of triacylglycerol (TAG) (Beopoulos et al 2011; Knothe 2009; Meng et al 2009; Sitepu et al 2014). Compared to other oleaginous microorganisms, Second-generation biodiesel is made from non-food sources such as rice straw, wood residue, corncob, and sugarcane bagasse Lignocellulosic hydrolysates from these feedstocks are composed mainly of glucose, xylose, and l-arabinose (hereafter referred to as arabinose) (Huang et al 2009; Kumar et al 2009; Madhavan et al 2012; Roberto et al 1995; Tsigie et al 2011). A previous study investigated lipid accumulation using a medium containing 3 % glucose by Vanrija musci JCM
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