Cyanobacterial blooms are a major problem in many lakes and can negatively impact public health and ecosystem services. The bioflocculation technique has proven to be a cost-effective, environmentally friendly technique with no secondary pollution to harvest multiple microalgae; however, few studies have focused on its effect on and potential for controlling cyanobacterial blooms in eutrophic lakes. In this study, the bioflocculation efficiencies of different Microcystis species under Glyptotendipes tokunagai (Diptera, Chironomidae) stress conditions and the interactions between secreted silk from Chironomid larvae and extracellular polymeric substances (EPS) from Microcystis were compared. The results indicated that G. tokunagai presented better bioflocculation efficiency on M. wesenbergii than on M. aeruginosa. The formation of “Large Algal Aggregate” flocs was promoted by the derived-soluble extracellular polymeric substances (i.e., proteins and polysaccharides, sEPS) from M. wesenbergii and silk from G. tokunagai. Both M. wesenbergii and midge silk had abundant functional groups, which was beneficial to the formation of the large aggregate. G. tokunagai secreted a large amount of silk to bridge with the sEPS of M. wesenbergii, forming a network structure via interaction between filamentous substance (i.e., complex of sEPS and silk) that plays an important role in the aggregation of Microcystis and the removal of the Microcystis biomass in the water column. The findings provide further insights that will benefit the existing efforts of combating Microcystis blooms in the water column via bioflocculation and will provide a new sustainable approach for inhibiting early bloom formation from the perspective of its provenance in the sediment-water interface.

蓝藻水华是许多湖泊的主要问题，可能对公共卫生和生态系统服务产生负面影响。生物絮凝技术已被证明是一种具有成本效益的，环境友好的技术，并且没有二次污染，因此可以收获多种微藻。然而，很少有研究集中于其对富营养化湖泊中蓝藻水华的影响和控制潜力。在这项研究中，比较了不同的微囊藻物种在Glyptotendipes tokunagai（Diptera，Chironomidae）胁迫条件下的生物絮凝效率，以及从Chironomid幼虫分泌的丝与微囊藻细胞外聚合物（EPS）之间的相互作用。结果表明G. tokunagai在Wesenbergii上表现出比铜绿假单胞菌更好的生物絮凝效率。韦森伯格氏菌和德克氏菌丝产生的可溶性胞外聚合物质（即蛋白质和多糖，sEPS）促进了“大藻类聚集体”絮凝物的形成。既惠氏微囊藻和蠓丝绸有丰富官能团，其是大的聚集体的形成是有益的。G. tokunagai分泌了大量的丝绸，以与Wesenbergii的sEPS搭桥，通过丝状物质（即sEPS和丝绸的复合物）之间的相互作用形成网络结构，这在微囊藻的聚集和水柱中微囊藻生物量的去除中起着重要作用。这些发现提供了进一步的见解，这将有益于通过生物絮凝技术对抗水柱中微囊藻水华的现有努力，并且从沉积物-水界面的来源来看，将为抑制早期水华的形成提供一种新的可持续方法。