Abstract
BackgroundOligocelluloses and oligoxyloses are partially hydrolyzed products from lignocellulosic biomass hydrolysis. Biomass hydrolysates usually contain monosaccharides as well as various amounts of oligosaccharides. To utilize biomass hydrolysates more efficiently, it is important to identify microorganisms capable of converting biomass-derived oligosaccharides into biofuels or biochemicals.ResultsWe have demonstrated that the oleaginous yeast Cryptococcus curvatus can utilize either oligocelluloses or oligoxyloses as sole carbon sources for microbial lipid production. When oligocelluloses were used, lipid content and lipid coefficient were 35.9% and 0.20 g/g consumed sugar, respectively. When oligoxyloses were used, lipid coefficient was 0.17 g/g consumed sugar. Ion chromatography analysis showed oligocelluloses with a degree of polymerization from 2 to 9 were assimilated. Our data suggested that these oligosaccharides were transported into cells and then hydrolyzed by cytoplasmic enzymes. Further analysis indicated that these enzymes were inducible by oligocelluloses. Lipid production on cellulose by C. curvatus using the simultaneous saccharification and lipid production process in the absence of cellobiase achieved essentially identical results to that in the presence of cellobiase, suggesting that oligocelluloses generated in situ were utilized with high efficiency. This study has provided inspiring information for oligosaccharides utilization, which should facilitate biorefinery based on lignocellulosic biomass.ConclusionsC. curvatus can directly utilize biomass-derived oligosaccharides. Oligocelluloses are transported into the cells and then hydrolyzed by cytoplasmic enzymes. A simultaneous saccharification and lipid production process can be conducted without oligocelluloses accumulation in the absence of cellobiase by C. curvatus, which could reduce the enzyme costs.
Highlights
Lignocellulosic biomass, such as agricultural residues and forestry wastes, has been widely recognized as a sustainable source for biofuels production [1]
Lipid production on oligosaccharides by C. curvatus Oligosaccharides are commonly found in biomass hydrolysates yet are difficult to utilize for some microorganisms [3]
We cultivated cells of the oleaginous yeast C. curvatus ATCC 20509 using oligocelluloses as carbon sources to identify an advantageous strain for microbial lipid production
Summary
Lignocellulosic biomass, such as agricultural residues and forestry wastes, has been widely recognized as a sustainable source for biofuels production [1]. Cellulose and hemicellulose, two major sugar polymers of lignocelluloses, have to be depolymerized by hydrolysis to enable more efficient microbial utilization. Oligocelluloses, water soluble oligomers of β-1,4-linked glucose, are the main incomplete hydrolyzed products of cellulose. Oligoxyloses, water soluble oligomers of β-1,4-linked xylose, are incomplete hydrolyzed products of hemicellulose. These oligomers are produced during biomass pretreatment as well as the hydrolysis process and may be further hydrolyzed to monosaccharides by glycosidases. Cellobiose is the simplest form of oligocellulose. It is a stronger inhibitor of cellulase than glucose, and remarkably slows down the rate of cellulose hydrolysis [6,7]. Oligocelluloses and oligoxyloses are partially hydrolyzed products from lignocellulosic biomass hydrolysis. To utilize biomass hydrolysates more efficiently, it is important to identify microorganisms capable of converting biomass-derived oligosaccharides into biofuels or biochemicals
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
