title: Aggregate formation and polysaccharide content of Chlorella pyrenoidosa Chick (Chlorophyta) in response to simulated nutrient stress.
abstract: To determine how polysaccharide production influences microalgal aggregate size, we stimulated polysaccharide production using existing methods (previously applied to cyanobacteria and plants). Cultures were treated with glyoxylate (0, 0.25, 0.5, 1.25 mmol/L) to simulate nutrient stress and examined for 9 days (approaching stationary phase on day 9) to assess: growth rate, polysaccharide production (soluble, bound, and total), aggregate size, and the relation between polysaccharide and aggregate size. We found: 1.25 mmol/L glyoxylate inhibits growth, but 0.25 and 0.5 mmol/L do not, allowing comparisons of aggregate formation at lower concentrations; glyoxylate-induced polysaccharide production, which increased with increased glyoxylate concentration and time; an increase in relative abundance of cells bound together with increased glyoxylate addition; and increased glyoxylate-stimulated polysaccharide levels were directly correlated with aggregate size. This study indicates that glyoxylate may be used to examine microalgal ecophysiology and offers a method to predict the influence of nutrient stress on polysaccharide production.
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210046, China. yangzhou@njnu.edu.cn
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Juan
authors.initials: J
authors.lastname: Ge
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yafen
authors.initials: Y
authors.lastname: Chen
authors.forename: David
authors.initials: D
authors.lastname: Montagnes
mesh_terms: D002708:Chlorella / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D006038:Glyoxylates / Q000494:pharmacology; D007700:Kinetics; D008954:Models, Biological; D011134:Polysaccharides / Q000378:metabolism*; D012995:Solubility / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D013997:Time Factors
chemical_list: D006038:Glyoxylates; D011134:Polysaccharides; C031150:glyoxylic acid