title: Enhanced accumulation of glycogen, lipids and polyhydroxybutyrate under optimal nutrients and light intensities in the cyanobacterium Synechocystis sp. PCC 6803.
abstract: OBJECTIVE
  Glycogen (GL) and lipids (LP) are efficient biofuel substrates, whereas polyhydroxybutyrate (PHB) is a potent biodegradable plastic. This study aimed to increase accumulation of these three compounds in Synechocystis sp. PCC 6803.
  
  
  RESULTS
  Under autophototrophic growth, co-accumulation of the three compounds reached maximum level in a mid-stationary phase at 39·2% of dry weight (22·7% GL, 14·1% LP and 2·4% PHB). Nitrogen deprivation increased this to 61·5% (36·8% GL, 11·2% LP and 13·5% PHB), higher than that achieved by phosphorus, sulfur, iron or calcium deprivation. Combining nitrogen deprivation with 0·4% (w/v) glucose addition for heterophototrophic growth and optimizing the light intensity (200 μmol photons m(-2) s(-1) ) synergistically enhanced combined accumulation to 71·1% of biomass (41·3% GL, 16·7% LP and 13·1% PHB), a higher level than previously reported in Synechocystis. However, the maximum coproductivity of GL, LP and PHB (at 0·72 g l(-1) ) was obtained in the 12-day heterophototrophic culture without nitrogen deprivation.
  
  
  CONCLUSIONS
  Accumulation of GL, LP and PHB was enhanced under both autophototrophic and heterophototrophic conditions by optimizations of nutrient and light supplies.
  
  
  CONCLUSIONS
  This study provides a means for increasing co-production of potent bioenergy substrates and useful biomaterials in Synechocystis which may also be applicable to other cyanobacteria.
authors.affiliation: Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: T
authors.initials: T
authors.lastname: Monshupanee
authors.forename: A
authors.initials: A
authors.lastname: Incharoensakdi
mesh_terms: D018533:Biomass; D003624:Darkness; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000378:metabolism*; D008027:Light; D050356:Lipid Metabolism; D052817:Phototrophic Processes; D046939:Synechocystis / Q000378:metabolism*
chemical_list: D006885:Hydroxybutyrates; D006003:Glycogen; D005947:Glucose
keywords: carbon source; cyanobacteria; glycogen; light; lipid; nutrients; polyhydroxybutyrate