Zhang Qi, Chen Yuchen, Wang Min, Zhang Jianyun, Chen Qiuwen, Liu Dongsheng
State Key Laboratory of Hydrology-Water Resources & Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing 210029, China; Center for Eco-Environment Research, Nanjing Hydraulic Research Institute, Nanjing 210029, China.
Center for Eco-Environment Research, Nanjing Hydraulic Research Institute, Nanjing 210029, China.
Water Res. 2021 May 15;196:117048. doi: 10.1016/j.watres.2021.117048. Epub 2021 Mar 15.
Toxic cyanobacteria bloom is a ubiquitous phenomenon worldwide in eutrophic lakes or reservoirs. Microcystis, is a cosmopolitan genus in cyanobacteria and exists in many different forms. Microcystis aeruginosa (M. aeruginosa) can produce microcystins (MCs) with strong liver toxicity during its growth and decomposition. Phosphorus (P) is a typical growth limiting factor of M. aeruginosa. Though different forms and concentrations of P are common in natural water, the molecular responses in the growth and MCs formation of M. aeruginosa remain unclear. In this study, laboratory experiments were conducted to determine the uptake of P, cell activity, MCs release, and related gene expression under different concentrations of dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP). We found that the growth of M. aeruginosa was promoted by increasing DIP concentration but coerced under high concentration (0.6 and 1.0 mg P/L) of DOP after P starvation. The growth stress was not related to the alkaline phosphatase activity (APA). Although alkaline phosphatase (AP) could convert DOP into algae absorbable DIP, the growth status of M. aeruginosa mainly depended on the response mechanism of phosphate transporter expression to the extracellular P concentration. High-concentration DIP promoted MCs production in M. aeruginosa, while high-concentration DOP triggered the release of intracellular MCs rather than affecting MCs production. Our study revealed the molecular responses of algal growth and toxin formation under different P sources, and provided a theoretical basis and novel idea for risk management of eutrophic lakes and reservoirs.
有毒蓝藻水华是富营养化湖泊或水库中全球普遍存在的现象。微囊藻是蓝藻中的一个世界性属，以多种不同形式存在。铜绿微囊藻在其生长和分解过程中可产生具有强烈肝毒性的微囊藻毒素（MCs）。磷（P）是铜绿微囊藻典型的生长限制因子。尽管天然水体中常见不同形态和浓度的磷，但铜绿微囊藻生长及微囊藻毒素形成过程中的分子响应仍不清楚。本研究通过实验室实验，测定了不同浓度溶解无机磷（DIP）和溶解有机磷（DOP）条件下铜绿微囊藻对磷的吸收、细胞活性、微囊藻毒素释放及相关基因表达。我们发现，增加DIP浓度可促进铜绿微囊藻生长，但在磷饥饿后，高浓度（0.6和1.0 mg P/L）DOP会抑制其生长。生长胁迫与碱性磷酸酶活性（APA）无关。虽然碱性磷酸酶（AP）可将DOP转化为藻类可吸收的DIP，但铜绿微囊藻的生长状态主要取决于磷酸盐转运蛋白表达对细胞外磷浓度的响应机制。高浓度DIP促进铜绿微囊藻产生微囊藻毒素，而高浓度DOP则触发细胞内微囊藻毒素的释放，而非影响微囊藻毒素的产生。我们的研究揭示了不同磷源条件下藻类生长和毒素形成的分子响应，为富营养化湖泊和水库的风险管理提供了理论依据和新思路。
