State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
Sci Total Environ. 2021 Jul 10;777:145870. doi: 10.1016/j.scitotenv.2021.145870. Epub 2021 Feb 16.
Quorum sensing (QS) plays an important role in biofilm formation and the start-up of biofilm-based reactors, while its involvement in bacterial assembly throughout biofilm development remains underexplored. We investigated the assembly and succession of the bacterial community in a full-scale integrated fixed-film activated sludge (IFAS) process, with emphasis on N-acylhomoserine lactone (AHL)-driven QS. Biofilm development could be divided into two major periods, (i) young biofilm formation phase and (ii) biofilm maturity and update phase. Mature biofilms exhibited lower levels of AHLs compared with young biofilms (p > 0.05). A structural equation model, constructed to assess the linkages between AHL level and bacterial community composition as well as environmental factors, indicated that pH significantly influenced both bacterial community composition and AHL content. Along with biofilm development, there was a negative correlation between AHL concentration and community composition variation (coefficients of -0.367 and -0.329). Regarding the lower AHL level in mature biofilms, these results were consistent with the phylogenetic molecular ecological networks (pMENs) analysis, indicating that quorum-quenching (QQ) bacteria occur in keystone taxa in mature biofilms. In addition, based on the pMENs results, the proportion of positive interactions increased from 77.64 to 82.39% in mature biofilms compared to young biofilms, indicating that bacterial cooperation was strengthened in mature biofilms. The QS bacteria were predominant in the keystone taxa of pMENs, with proportions being increased to 62% in mature biofilms, which is conducive for biofilm development. Overall, this study improves our understanding of the involvement of AHL-mediated QS in biofilm development.
群体感应（QS）在生物膜形成和基于生物膜的反应器启动中起着重要作用，而其在生物膜发展过程中对细菌组装的参与仍未得到充分探索。我们研究了在全规模集成固定膜活性污泥（IFAS）工艺中细菌群落的组装和演替，重点是 N-酰基高丝氨酸内酯（AHL）驱动的 QS。生物膜的发展可以分为两个主要阶段，（i）年轻生物膜的形成阶段和（ii）生物膜成熟和更新阶段。成熟生物膜中的 AHL 水平低于年轻生物膜（p>0.05）。构建结构方程模型，以评估 AHL 水平与细菌群落组成以及环境因素之间的联系，表明 pH 值显著影响细菌群落组成和 AHL 含量。随着生物膜的发展，AHL 浓度与群落组成变化之间存在负相关（系数分别为-0.367 和-0.329）。考虑到成熟生物膜中 AHL 水平较低，这些结果与系统发育分子生态网络（pMENs）分析一致，表明在成熟生物膜中，群体感应淬灭（QQ）细菌存在于关键类群中。此外，基于 pMENs 的结果，成熟生物膜中阳性相互作用的比例从年轻生物膜的 77.64%增加到 82.39%，表明成熟生物膜中细菌的合作得到了加强。QS 细菌在 pMENs 的关键类群中占主导地位，其比例从年轻生物膜的 44%增加到成熟生物膜的 62%，这有利于生物膜的发展。总的来说，本研究提高了我们对 AHL 介导的 QS 在生物膜发展中的参与的理解。
