title: Relationship of energy charge and toxin content of Microcystis aeruginosa in nitrogen-limited or phosphorous-limited cultures.
abstract: Effects of nitrogen-limitation and phosphorus-limitation on microcystin (MC) content and energy charge (EC) of the Microcystis aeruginosa were investigated in batch cultures and semi-continuous cultures. In batch cultures, nitrogen-limitation retarded the MC synthesis and phosphorus-limitation had little effects on MC production. The EC remained constant in nitrogen-limited cultures, while it decreased largely when phosphorus was extinct in phosphorus-limited culture. In the semi-continuous cultures, MC production in nitrogen- and phosphorus-limited cultures increased with the increase of dilution rate; however, MC content in phosphorus-limited cultures was more than that in nitrogen-limited cultures. The EC in nitrogen-limited cultures remained constant and in phosphorus-limited cultures increased with the increase of dilution rate. In phosphorus-limited semi-continuous cultures, a direct relationship between EC and MC content was demonstrated. No correlation was observed in nitrogen-limited semi-continuous cultures. Based on the above analysis, a mechanism of nitrogen and phosphorus effect on the MC synthesis was suggested, that the MC synthesis was determined by the combination of necessary enzymes and precursors and EC.
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Ruihua
authors.initials: R
authors.lastname: Dai
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
authors.forename: Jiuhui
authors.initials: J
authors.lastname: Qu
authors.forename: Xu
authors.initials: X
authors.lastname: Zhao
authors.forename: Jia
authors.initials: J
authors.lastname: Ru
authors.forename: Yining
authors.initials: Y
authors.lastname: Hou
mesh_terms: D001431:Bacteriological Techniques; D004734:Energy Metabolism; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism; D046931:Microcystis / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*
chemical_list: D008387:Marine Toxins; D052998:Microcystins; D010758:Phosphorus; C063855:microcystin RR; C057862:cyanoginosin LR; D009584:Nitrogen