Selection of quorum quenching (QQ) bacteria for membrane biofouling control: effect of different Gram-staining QQ bacteria, Bacillus sp. T5 and Delftia sp. T6, on microbial population in membrane bioreactors

Abstract

This study aimed to address the gap in understanding how the microbial community present within quorum quenching-membrane bioreactor (QQ-MBRs) changes during the operations by investigating the behavior of two different types of QQ bacteria, Bacillus sp. T5 and Delftia sp. T6. The anti-biofouling effects of T5 and T6 in the QQ-MBR were 85% and 76%, respectively. According to the Illumina HiSeq results, when the QQ-MBR was operated with Gram-positive bacteria, T5, in the mixed liquor a reduction was observed in Gram-positive bacteria and Gram-negative bacteria population increased. In contrast, when the QQ-MBR was operated with Gram-negative bacteria, T6, Gram-negative bacteria population reduced and an increase in Gram-positive bacteria observed. As such, the outputs of the Illumina analysis revealed that use of Gram-negative QQ bacteria in the reactor induced a Gram-positive microbial community and vice versa. This indicates that a close interaction occurs between indigenous Gram-negative and positive bacterial phyla, and Bacillus sp. T5/Delftia sp. T6 is fundamental to the performance of MBRs. This is the first study demonstrating such a relationship and assistance selecting QQ bacteria/strategy in an effective way.

Transcriptome Landscape of Intracellular Brucella ovis Surviving in RAW264.7 Macrophage Immune System

“…When the microbial population reaches a certain density level, the concentration of signaling molecules reaches a threshold value. By signal transduction through related proteins, including receptor protein kinases, signals are transmitted across the cells, thus affecting the expression of specific genes and regulating the physiological characteristics of microbial populations [44][45][46]. Bacteria use quorum sensing for cell-to-cell communication and coordination of activities in the complex environment, which enables the entire bacterial population to survive [47][48][49].…”

Friends or Foes—Microbial Interactions in Nature

“…into a nontoxic paint, bacterial and diatoms colonization and growth were successfully controlled by QS interference in artificial marine settings [234]. In industry, QQ is applied in wastewater treatment, where membrane bioreactors used for reclamation and desalination of brackish and seawater are constrained by biofouling of the membrane filters [235]. Fouling biofilms formed by Aeromonas hydrophila and P. putida [236] are prevented by small-signal interfering compounds added to antifouling coatings or by immobilizing QQ enzymes or marine organisms engineered to secrete QS inhibitors [237][238][239][240].…”

Membrane processes

“…Additionally, the research concluded that the interaction of T5 concerning Gram-negative and Gram-positive bacteria was critical to MBR performance. Gül, Imer, Park, and Koyuncu (2018b) also conducted research on antifouling behavior and the associated impact on the microbial community for two different QQ species: Bacillus sp. T5 and Delftia sp.…”

“…Gül, Imer, Park, and Koyuncu (2018b) also conducted research on antifouling behavior and the associated impact on the microbial community for two different QQ species: Bacillus sp. T5 and Delftia sp.…”