Sustainable Production of Microbial Lipids from Lignocellulosic Biomass Using Oleaginous Yeast Cultures

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 feedstocks 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 , 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.

Co-production of single cell oil and gluconic acid using oleaginous Cryptococcus podzolicus DSM 27192

“…When Y. lipolytica was cultivated with high initial glucose concentration, the concentration of cellular oleic acid decreased, while linoleic acid slightly increased [36]. This could be caused by an increased desaturation of oleic acid by Δ 12 desaturase within the fatty acid elongation cycle [37]. Therefore, optimizing the initial glucose concentration might be an easy way to upgrade SCO value by enhancing the content of polyunsaturated fatty acids in C. podzolicus DSM 27192 and other oleaginous yeasts.…”

Production of free fatty acids from switchgrass using recombinant Escherichia coli

“…Another study also mentioned that citric acid, which was included during enzymatic hydrolysis, was used as a carbon source. Lee et al reported that citric acid can be consumed by oleaginous yeast species . Therefore, it would be better to consider alternative chemicals to replace the citrate buffer during enzymatic hydrolysis for lignocellulose‐based sugar stream production.…”

“…Another study also mentioned that citric acid, which was included during enzymatic hydrolysis, was used as a carbon source. Lee et al 22 reported Total extractives were sum of alcohol-soluble extractives and watersoluble extractives. that citric acid can be consumed by oleaginous yeast species.…”

“…that citric acid can be consumed by oleaginous yeast species. 22 Therefore, it would be better to consider alternative chemicals to replace the citrate buffer during enzymatic hydrolysis for lignocellulose-based sugar stream production. In addition, substantially higher DCW, higher Yxs, and lower Ypx were achieved using switchgrass hydrolysates.…”

“…Corresponding concerning this article should be addressed to J. Lee at ljungeunlee2@gmail.com Figure 1 shows the metabolic pathway for FFA production in the recombinant E. coli strain used in this study. FA synthesis is initiated by the carboxylation of acetyl-CoA to malonyl-CoA, followed by condensation to a linear acyl chain, which normally is C 12 to C 22 carbons. The FFAs are released by thioesterase and secreted into the medium.…”