State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, P. R. China.
Nanjing Guohuan Science and Technology Co., Ltd of Nanjing Institute of Environmental Sciences, MEP, Nanjing, P.R. China.
PLoS One. 2018 May 3;13(5):e0195205. doi: 10.1371/journal.pone.0195205. eCollection 2018.
Cyanobacterial blooms are a worldwide environmental problem and frequently occur in eutrophic lakes. Organophosphorus mineralization regulated by microbial alkaline phosphatase provides available nutrients for bloom regeneration. To uncover the dynamics of bacterial alkaline phosphatase activity and microbial backgrounds in relation to organophosphorus mineralization during the decomposition process of cyanobacterial blooms, the response of alkaline phosphatase PhoX-producing bacteria were explored using a 23-day mesocosm experiment with three varying densities of Microcystis biomass from eutrophic Lake Taihu. Our study found large amounts of soluble reactive phosphorus and dissolved organophosphorus were released into the lake water during the decomposition process. Bacterial alkaline phosphatase activity showed the peak values during days 57 in groups with different chlorophyll-a densities, and then all decreased dramatically to their initial experimental levels during the last stage of decomposition. Bacterial phoX abundances in the three experimental groups increased significantly along with the decomposition process, positively related to the dissolved organic carbon and organophosphorus released by the Microcystis blooms. The genotypes similar to the phoX genes of Alphaproteobacteria were dominant in all groups, whereas the genotypes most similar to the phoX genes of Betaproteobacteria and Cyanobacteria were also abundant in the low density (15 μg L-1 chlorophyll-a) group. At the end of the decomposition process, the number of genotypes most similar to the phoX of Betaproteobacteria and Cyanobacteria increased in the medium (150 μg L-1 chlorophyll-a) and high (1500 μg L-1 chlorophyll-a) density groups. The released organophosphorus and increased bacterial phoX abundance after decomposition of Microcystis aggregates could potentially provide sufficient nutrients and biological conditions for algal proliferation and are probably related to the regeneration of Microcystis blooms in eutrophic lakes.
蓝藻水华是一个全球性的环境问题，经常发生在富营养化的湖泊中。微生物碱性磷酸酶调控的有机磷矿化作用为水华的再生提供了可用的养分。为了揭示蓝藻水华分解过程中与有机磷矿化作用相关的细菌碱性磷酸酶活性和微生物背景的动态变化，我们利用来自富营养化太湖的三种不同微囊藻生物量密度的 23 天中观实验，探索了碱性磷酸酶 PhoX 产生菌的响应。我们的研究发现，在分解过程中，大量的可溶反应性磷和溶解有机磷被释放到湖水中。在不同叶绿素-a 密度的组中，细菌碱性磷酸酶活性在第 57 天达到峰值，然后在分解的最后阶段急剧下降到初始实验水平。在三个实验组中，细菌 phoX 丰度随着分解过程的进行而显著增加，与微囊藻水华释放的溶解有机碳和有机磷呈正相关。所有组中都以α变形菌的 phoX 基因相似型为主导，而β变形菌和蓝藻的 phoX 基因相似型在低密度（15 μg L-1 叶绿素-a）组中也很丰富。在分解过程结束时，中密度（150 μg L-1 叶绿素-a）和高密度（1500 μg L-1 叶绿素-a）组中与 Betaproteobacteria 和 Cyanobacteria 的 phoX 基因最相似的基因型数量增加。微囊藻聚集体分解后释放的有机磷和增加的细菌 phoX 丰度可能为藻类的增殖提供了足够的养分和生物条件，这可能与富营养化湖泊中微囊藻水华的再生有关。
