Institute for Ocean Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, Guangdong Province, PR China.
Institute for Ocean Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, Guangdong Province, PR China; State Key Laboratory of Marine Resource Utilization in the South China Sea, Hainan University, Haikou 570228, Hainan Province, PR China.
Sci Total Environ. 2022 Dec 10;851(Pt 2):158354. doi: 10.1016/j.scitotenv.2022.158354. Epub 2022 Aug 28.
Microbial aggregates play key roles in cyanobacterial blooms. Being a bacterial communication mechanism, quorum sensing (QS) synchronizes gene expression in a density-dependent manner and regulates bacterial physiological behavior. However, the regulatory role of QS in the formation of cyanobacteria-associated bacterial aggregates remains poorly understood. Here, we present insight into the role of QS in regulating bacterial aggregate formation in a representative bacterial strain, Novosphingobium sp. ERN07, which was isolated from Microcystis blooms in Lake Taihu. A biosensor assay showed that ERN07 exhibits significant AHL-producing capacity. Biochemical and microscopic analysis revealed that this strain possesses the ability to form aggregated communities. Gene knockout experiments indicated that the AHL-mediated QS system positively regulates bacterial aggregation. The aggregated communities possess the ability to enhance the production of extracellular polymeric substances (EPS), alter EPS composition ratios, and affect biofilm formation. The addition of aggregated substances also has a significant growth-promoting effect on M. aeruginosa. Transcriptomic analysis revealed that the aggregated substances positively regulate photosynthetic efficiency and energy metabolism of M. aeruginosa. These findings show that QS can mediate the aggregation phenotype and associated substrate spectrum composition, contributing to a better understanding of microalgal-bacterial interactions and mechanisms of Microcystis bloom maintenance in the natural environment.
微生物聚集体在蓝藻水华的形成中起着关键作用。群体感应（QS）是一种细菌通讯机制，它以密度依赖的方式同步基因表达，并调节细菌的生理行为。然而，QS 在调节与蓝藻相关的细菌聚集体形成中的调控作用仍知之甚少。在这里，我们深入了解了群体感应在调节从太湖蓝藻水华分离的典型细菌菌株新鞘氨醇单胞菌 ERN07 形成细菌聚集体中的作用。生物传感器测定表明，ERN07 具有显著的 AHL 产生能力。生化和显微镜分析表明，该菌株具有形成聚集群落的能力。基因敲除实验表明，AHL 介导的 QS 系统正向调节细菌聚集。聚集群落具有增强胞外聚合物（EPS）产生、改变 EPS 组成比例和影响生物膜形成的能力。聚集物质的添加对铜绿微囊藻也有显著的促生长作用。转录组分析表明，聚集物质正向调节铜绿微囊藻的光合作用效率和能量代谢。这些发现表明，QS 可以介导聚集表型和相关基质谱组成，有助于更好地理解微藻-细菌相互作用和微囊藻水华在自然环境中的维持机制。
