title: Effects of growth condition on the structure of glycogen produced in cyanobacterium Synechocystis sp. PCC6803.
abstract: Growth and glycogen production were characterized for Synechocystis sp. strain PCC6803 grown under continuous fluorescent light in four variations of BG-11 medium: either with (G+) or without (G-) 5mM glucose, and with a normal (N+, 1.5 g sodium nitrate/L) or a reduced (N-, 0.084 g sodium nitrate/L) nitrogen concentration. Glucose-supplemented BG-11 with a normal nitrogen concentration (N+G+) produced the highest growth rate and the greatest cell density. Although the maximum cell mass production was observed in the N+G+ medium, the highest glycogen yield (19.0mg/g wet cell mass) was achieved under the glucose-supplemented, nitrogen-limiting condition (N-G+). The addition of glucose enhanced cell growth, while nitrogen limitation apparently directed carbon flux into glycogen accumulation rather than cell growth. Transmission electron microscopic analysis showed that, under nitrogen-limiting conditions (N-G+), glycogen particles accumulated in large amounts and filled the cytosol of the cells. Analysis by high-performance size-exclusion chromatography further revealed that the glycogen produced in N-G+ medium had the longest average branch chain-length (DP10.4) among the conditions tested. When the yield and structure of glycogen were examined in different growth phases, the greatest yield (36.6 mg/g wet cell mass) and the longest branch chain-length (DP10.7) were observed 2 days after the fully grown cells in the N+G+ medium were transferred to the growth restricting (N-G+) medium.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50010, USA. shyoo@sejong.ac.kr
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Yoo
authors.forename: Catherine
authors.initials: C
authors.lastname: Keppel
authors.forename: Martin
authors.initials: M
authors.lastname: Spalding
authors.forename: Jay-lin
authors.initials: JL
authors.lastname: Jane
mesh_terms: D003470:Culture Media / Q000494:pharmacology; D005453:Fluorescence; D006003:Glycogen / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D046529:Microscopy, Electron, Transmission; D046939:Synechocystis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D003470:Culture Media; D006003:Glycogen