Department of Civil and Environmental Engineering, Shantou University, Guangdong, 515063, China; Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology, H-12 Sector, Islamabad, Pakistan; Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
Department of Civil and Environmental Engineering, Shantou University, Guangdong, 515063, China; Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
Chemosphere. 2020 May;247:125953. doi: 10.1016/j.chemosphere.2020.125953. Epub 2020 Jan 18.
In conventional membrane bioreactor (MBR) treatment systems, Gram-negative bacterial population appears to be always outnumbered Gram-positive community. Thereby, acyl homoserine lactones (AHLs), major signaling molecules utilized by Gram-negative bacteria, have been targeted for biofouling control in quorum quenching (QQ) based studies. This study investigated the impact of AHL and autoinducer-2 (AI-2)-degrading QQ consortium on the selective accumulation of microbial communities in a QQ MBR (MBR-QQb). The results show that addition of the QQ consortium (in the form of beads) increased the filtration time of MBR-QQb by 3.5 times. The distribution of mixed liquor extracellular polymeric substances (EPS), especially the tightly bound (TB) proteinous EPS and the floc size were strongly affected by the QQ activity, and the endless 'battle' between QQ and quorum sensing (QS). More importantly, QQ induced the significant suppression of Gram-negative bacterial community. The average abundance of Gram-positive bacteria at the genus level in the biocake of MBR-QQb (51%) was significantly higher than that of the control MBR (11%) and the MBR with vacant beads (28%). These findings suggest that an unintended condition is created to favor the growth of Gram-positive bacteria in QQ MBRs, resulting in a distinct microbial social network in both bulk sludge and biocake.
在传统的膜生物反应器（MBR）处理系统中，革兰氏阴性菌的数量似乎总是超过革兰氏阳性菌。因此，酰基高丝氨酸内酯（AHLs），革兰氏阴性菌使用的主要信号分子，已成为基于群体感应淬灭（QQ）的生物污控制的目标。本研究调查了 AHL 和自动诱导物-2（AI-2）降解 QQ 联合体对 QQ MBR（MBR-QQb）中微生物群落选择性积累的影响。结果表明，添加 QQ 联合体（以珠粒的形式）使 MBR-QQb 的过滤时间增加了 3.5 倍。混合液胞外聚合物（EPS）的分布，特别是紧密结合（TB）蛋白 EPS 和絮体大小，受到 QQ 活性的强烈影响，以及 QQ 和群体感应（QS）之间无休止的“战斗”。更重要的是，QQ 诱导了革兰氏阴性菌群落的显著抑制。MBR-QQb 生物膜中革兰氏阳性菌属水平的平均丰度（51%）明显高于对照 MBR（11%）和带有空珠粒的 MBR（28%）。这些发现表明，在 QQ MBR 中创造了一种不利于革兰氏阴性菌生长的意外条件，导致在絮体和生物膜中形成了明显不同的微生物社交网络。
