title: Biosynthesis of high yield fatty acids from Chlorella vulgaris NIES-227 under nitrogen starvation stress during heterotrophic cultivation.
abstract: In this study the heterotrophic cultivation of Chlorella vulgaris NIES-227 fed with glucose was investigated systematically using six media types; combinations of nitrogen repletion/depletion and phosphorus repletion/limitation/depletion. It was found that a high yield of fatty acids (0.88 of fed glucose-COD) and a high content of fatty acid methyl esters (FAMEs) (89% of dry weight) were obtained under nitrogen starved conditions. To our knowledge it is the first report on such high COD conversion yield and FAME content in microalgae. The dominant fatty acid (>50%) was methyl oleate (C18:1), a desirable component for biodiesel synthesis. FAME content under nitrogen starved conditions was significantly higher than under nitrogen sufficient conditions, while phosphorus had no significant influence, indicating that nitrogen starvation was the real "fatty acids trigger" in heterotrophic cultivation. These findings could simplify the downstream extraction process, such as the extrusion of oil from soybeans, and could reduce operating costs by improving the fatty acid yield from waste COD.
authors.affiliation: Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou, PR China.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Shen
authors.affiliation: Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou, PR China.
authors.forename: Fei-Fei
authors.initials: FF
authors.lastname: Chu
authors.affiliation: Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou, PR China; State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Lam
authors.affiliation: Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou, PR China; CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, PR China. Electronic address: rzeng@ustc.edu.cn.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
mesh_terms: D056804:Biofuels / Q000382:microbiology; D048408:Chlorella vulgaris / Q000254:growth & development / Q000378:metabolism*; D005227:Fatty Acids / Q000096:biosynthesis*; D005947:Glucose / Q000378:metabolism; D052836:Heterotrophic Processes; D008055:Lipids / Q000096:biosynthesis; D009584:Nitrogen / Q000172:deficiency*; D010758:Phosphorus / Q000378:metabolism
chemical_list: D056804:Biofuels; D005227:Fatty Acids; D008055:Lipids; D010758:Phosphorus; D005947:Glucose; D009584:Nitrogen
keywords: Fatty acid content; Fatty acid yield; Glucose; Heterotrophic cultivation; Microalgae; Nitrogen starvation