Abstract
Microbial lipids derived from oleaginous yeast could be a promising resource for biodiesel and other oleochemical materials. The objective of this study was to develop an efficient bioconversion process from lignocellulosic biomass to microbial lipids using three types of robust oleaginous yeast: T. oleaginosus, L. starkeyi, and C. albidus. Sorghum stalks and switchgrass were utilized as feed-stocks for lipid production. Among oleaginous yeast strains, T. oleaginous showed better performance for lipid production using sorghum stalk hydrolysates. Lipid titers of 13.1 g·L-1 were achieved by T. oleaginosus, using sorghum stalk hydrolysates with lipid content of 60% (wt·wt-1) and high lipid yield of 0.29 g·g-1, which was substantially higher than the value reported in literature. Assessment of overall lipid yield revealed a total of 14.3 g and 13.3 g lipids were produced by T. oleaginosus from 100 g of raw sorghum stalks and switchgrass, respectively. This study revealed that minimization of sugar loss during pretreatment and selection of appropriate yeast strains would be key factors to develop an efficient bioconversion process and improve the industrial feasibility in a lignocellulose-based biorefinery.
Highlights
IntroductionA supply of low-cost carbohydrates for microbes is required for sustainable and cost-effective production of bio-based lipids
Lipid titers of 13.1 g∙L−1 were achieved by T. oleaginosus, using sorghum stalk hydrolysates with lipid content of 60% and high lipid yield of 0.29 g∙g−1, which was substantially higher than the value reported in literature
Switchgrass structure was 35% glucan and 29% xylan, containing higher amounts of total polysaccharides compared with sorghum stalks
Summary
A supply of low-cost carbohydrates for microbes is required for sustainable and cost-effective production of bio-based lipids. Lignocellulosic biomass, such as agricultural residues and woody crops, is a strong alternative substrate for microbial lipid production due to their abundance, low-cost investment, and high content of polysaccharides (up to 75%) [5] [6]. More than 90% of global production of plant biomass is lignocellulosic biomass, which is composed of cellulose, hemicellulose, and lignin [7]. The most abundant monomer sugars derived from lignocellulosic biomass are D-glucose, since cellulose represents 70% of total plant cell walls, repeating the β-(1→4) glycosidic bond [13]. Species of lignocellulosic-based monomer sugars depend on biomass types
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