title: Photosynthetic carbon partitioning and lipid production in the oleaginous microalga Pseudochlorococcum sp. (Chlorophyceae) under nitrogen-limited conditions.
abstract: Photosynthetic carbon partitioning into starch and neutral lipid was investigated in the oleaginous green microalga Pseudochlorococcum sp. When grown under low light and nitrogen-replete conditions, the algal cells possessed a basal level of starch. When grown under high light and nitrogen-limited conditions, starch synthesis was transiently up-regulated. After nitrogen depletion, starch content decreased while neutral lipid rapidly increased to 52.1% of cell dry weight, with a maximum neutral lipid productivity of 0.35 g L(-1)D(-1). These results suggest that Pseudochlorococcum used starch as a primary carbon and energy storage product. As nitrogen was depleted for an extended period of time, cells shift the carbon partitioning into neutral lipid as a secondary storage product. Partial inhibition of starch synthesis and degradation enzymes resulted in a decrease in neutral lipid content, indicating that conversion of starch to neutral lipid may contribute to overall neutral lipid accumulation. Biotechnological application of Pseudochlorococcum sp. as a production strain for biofuel was assessed.
authors.affiliation: Department of Applied Sciences and Mathematics, Arizona State University, Polytechnic Campus, 7001 E Williams Field Road, Mesa, AZ 85212, USA.
authors.forename: Yantao
authors.initials: Y
authors.lastname: Li
authors.forename: Danxiang
authors.initials: D
authors.lastname: Han
authors.forename: Milton
authors.initials: M
authors.lastname: Sommerfeld
authors.forename: Qiang
authors.initials: Q
authors.lastname: Hu
mesh_terms: D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism*; D000460:Chlorophyta / Q000254:growth & development / Q000378:metabolism*; D008027:Light; D008055:Lipids / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D013213:Starch / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D008055:Lipids; D002244:Carbon; D013213:Starch; D009584:Nitrogen