The selective pressure of quorum quenching on microbial communities in membrane bioreactors. (May 2020)

• Record Type: Journal Article
• Authors: Waheed, Hira; Xiao, Yeyuan; Hashmi, Imran; Zhou, Yan
• Is Part Of: Chemosphere. Volume 247(2020)
• Publication Date: 2020-05
• Subjects: Membrane bioreactor (MBR) -- Biofouling control -- Quorum quenching -- Microbial composition; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.125953
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: 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. Graphical abstract: Image 1 Highlights: QQ changed sludge morphology via controlling TB-EPS and PS/PN in EPS. The endless 'battle' between QQ and QS resulted in huge varations in sludge floc size and EPS content. AHL based QQ altered microbial composition, thus facilitated Gram-positive community. Survival of QQ strains within beads need to be maintained and monitored.