ABSTRACT
Cyclopentyl methyl ether (CPME) was evaluated for extracting oil or triacylglycerol (TAG) from wet cells of the oleaginous yeast Lipomyces starkeyi. CPME is a greener alternative to chloroform as a potential solvent for oil recovery. A monophasic system of CPME and biphasic system of CPME:water (1:0.7) performed poorly having the lowest TAG extraction efficiency and TAG selectivity compared to other monophasic systems of hexane and chloroform and the biphasic Bligh and Dyer method (chloroform:methanol:water). Biphasic systems of CPME:water:alcohol (methanol/ethanol/1-propanol) were tested and methanol achieved the best oil extraction efficiency compared to ethanol and 1-propanol. Different biphasic systems of CPME:methanol:water were tested, the best TAG extraction efficiency and TAG selectivity achieved was 9.9 mg/mL and 64.6%, respectively, using a starting ratio of 1:1.7:0.6 and a final ratio of 1:1:0.8 (CPME:methanol:water). Similar results were achieved for the Bligh and Dyer method (TAG extraction efficiency of 10.2 mg/mL and TAG selectivity of 66.0%) indicating that the biphasic CPME system was comparable. The fatty acid profile remained constant across all the solvent systems tested indicating that choice of solvent was not specific for any certain fatty acid. This study was able to demonstrate that CPME could be used as an alternative solvent for the extraction of oil from the wet biomass of oleaginous yeast. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1096-1103, 2017.
Subject(s)
Cyclopentanes/chemistry , Lipomyces/chemistry , Methyl Ethers/chemistry , Oils/chemistry , Oils/isolation & purification , Solvents/chemistry , Triglycerides/isolation & purification , Triglycerides/chemistryABSTRACT
Yeast single cell oil (SCO) is a non-crop-based, renewable oil source that can be used for the production of bio-based oleochemicals. Stand-alone production of SCO for oleochemicals is currently not cost-competitive because lower-cost alternatives from petroleum and crop-based resources are available. Utilizing low-valued nutrient sources, implementing cost-efficient downstream processes and adopting biotechnological advancements such as systems biology and metabolic engineering could prove valuable in making an SCO platform a reality in the emerging bio-based economy. This review aims to consider key biochemical pathways for storage lipid synthesis, possible pathways for SCO yield improvement, previously used bioprocessing techniques for SCO production, challenges in SCO commercialization and advantages of adopting a renewable SCO platform.
Subject(s)
Oils/metabolism , Yeasts/metabolism , Fermentation , Metabolic Engineering , Triglycerides/metabolismABSTRACT
Single cell oil (SCO) is a valuable noncrop-based renewable oil source. Hemicellulose derived sugars can be utilized to produce SCO using the oleaginous yeast Lipomyces starkeyi ATCC 56304. Bran by-products were tested as hemicellulose-rich feedstocks for the production of SCO. Whole and destarched corn and wheat bran hydrolysates were produced using hydrothermal and dilute sulfuric acid (0%, 0.5%, 1.0%, v/v) pretreatment along with enzymatic hydrolysis. Whole bran hydrolysates produced from hydrothermal pretreatment generated the highest average oil yields of 126.7 and 124.3 mg oil/g sugar for both wheat and corn bran, respectively. 1.0% acid pretreatment was effective for the destarched bran generating a hemicellulose hydrolysis efficiency of 94% and 84% for wheat and corn bran, respectively, resulting in the highest oil yield of 70.7 mg oil/g sugar. The results indicate pretreated corn and wheat bran hydrolysates can serve as viable feedstocks for oleaginous yeast SCO bioconversion.
