Phosphorus is one of the important factors to successfully establish the microalgal-bacterial symbiosis (MABS) system. The migration and transformation of phosphorus can occur in various ways, and the effects of phosphate on the MABS system facing environmental impacts like heavy metal stress are often ignored. This study investigated the roles of phosphate on the response of the MABS system to zinc ion (Zn). The results showed that the pollutant removal effect in the MABS system was significantly reduced, and microbial growth and activity were inhibited with the presence of Zn. When phosphate and Zn coexisted, the inhibition effects of pollutants removal and microbial growth rate were mitigated compared to that of only with the presence of Zn, with the increasing rates of 28.3% for total nitrogen removal, 48.9% for chemical oxygen demand removal, 78.3% for chlorophyll-a concentration, and 13.3% for volatile suspended solids concentration. When phosphate was subsequently supplemented in the MABS system after adding Zn, both pollutants removal efficiency and microbial growth and activity were not recovered. Thus, the inhibition effect of Zn on the MABS system was irreversible. Further analysis showed that Zn preferentially combined with phosphate could form chemical precipitate, which reduced the fixation of MABS system for Zn through extracellular adsorption and intracellular uptake. Under Zn stress, the succession of microbial communities occurred, and was more tolerant to Zn. This study revealed the comprehensive response mechanism of the co-effects of phosphate and Zn on the MABS system, and provided some insights for the MABS system treating wastewater containing heavy metals, as well as migration and transformation of heavy metals in aquatic ecosystems.

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磷酸盐在微藻-细菌共生系统处理重金属废水中的作用

磷是成功建立微藻-细菌共生（MABS）系统的重要因素之一。磷的迁移和转化可以通过多种方式发生，而磷酸盐对面临重金属胁迫等环境影响的MABS系统的影响往往被忽视。本研究研究了磷酸盐在 MABS 系统对锌离子 (Zn) 响应中的作用。结果表明，Zn的存在使MABS系统污染物去除效果显着降低，微生物生长和活性受到抑制。磷酸盐与Zn共存时,污染物去除率和微生物生长速率的抑制效果较单独Zn存在时有所减轻,总氮去除率提高了28.3%,化学需氧量去除率提高了48.9%,化学需氧量去除率提高了78.3%。 % 为叶绿素-a 浓度，13.3% 为挥发性悬浮固体浓度。当添加Zn后随后在MABS系统中补充磷酸盐时，污染物去除效率和微生物生长和活性都没有恢复。因此，Zn对MABS系统的抑制作用是不可逆的。进一步分析表明，Zn优先与磷酸盐结合形成化学沉淀，从而减少了MABS系统通过细胞外吸附和细胞内摄取对Zn的固定。在锌胁迫下，微生物群落发生演替，对锌的耐受性更强。该研究揭示了磷酸盐和锌的协同作用对MABS系统的综合响应机制，为MABS系统处理含重金属废水以及重金属在水生生态系统中的迁移转化提供了一些见解。