title: Variations of Growth and Toxin Yield in Cylindrospermopsis raciborskii under Different Phosphorus Concentrations.
abstract: The bloom-forming cyanobacteria,Cylindrospermopsis raciborskii, is a producer of the cytotoxic cylindrospermopsin (CYN). In this study, the growth, toxin yield, and expression of CYN biosynthesis genes ofC. raciborskiiwere examined under varying phosphorus (P) concentrations. The results show the cell number at 0.00 and 0.01 mg·L-1P was significantly lower than that at higher P concentrations (≥0.5 mg·L-1). The chlorophyllacontent, filament length, heterocyst, and akinete numbers at P ≤ 0.05 mg·L-1were also significantly reduced. The intracellular and extracellular CYN concentrations and the extracellular proportions increased during the culture period, and larger values were observed at higher P concentrations. Total CYN content reached 45.34-63.83 fg·cell-1and extracellular CYN proportion reached 11.49%-20.44% at the stationary growth phase. A significantly positive correlation was observed between CYN production and cell growth rate. Threecyrgenes were expressed constantly even at P-deficient conditions. The transcription ofcyrgenes at P-replete conditions or after P supplementation increased from 1.18-fold to 8.33-fold. In conclusion,C. raciborskiimay rapidly reorganize metabolic processes as an adaptive response to environmental P fluctuations. CYN production andcyrgene expression were constitutive metabolic processes in toxicC. raciborskii.
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. yangyiming9191@163.com.|University of Chinese Academy of Sciences, Beijing 100049, China. yangyiming9191@163.com.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Shenzhen Key Laboratory of Marine Bio-Resource and Eco-Environmental Science, Shenzhen University, Shenzhen 518060, Guangdong, China. jyg1949@163.com.
authors.forename: Yongguang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. xiaochuangli201@gmail.com.|University of Chinese Academy of Sciences, Beijing 100049, China. xiaochuangli201@gmail.com.
authors.forename: Xiaochuang
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. lih@ihb.ac.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. chenyouxin@ihb.ac.cn.|University of Chinese Academy of Sciences, Beijing 100049, China. chenyouxin@ihb.ac.cn.
authors.forename: Youxin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. xiejinlin1991@sina.com.|College of Life Sciences, Jiangxi Normal University, Nanchang 330022, Jiangxi, China. xiejinlin1991@sina.com.
authors.forename: Jinlin
authors.initials: J
authors.lastname: Xie
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. cai15926359926@163.com.|University of Chinese Academy of Sciences, Beijing 100049, China. cai15926359926@163.com.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Cai
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China. reli@ihb.ac.cn.
authors.forename: Renhui
authors.initials: R
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D003470:Culture Media / Q000737:chemistry; D046891:Cylindrospermopsis / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D010758:Phosphorus / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003470:Culture Media; D002734:Chlorophyll; D010758:Phosphorus; D000077194:Chlorophyll A
keywords: Cylindrospermopsis raciborskii; cylindrospermopsin; cyr gene; growth rate; inorganic phosphorus