Quorum sensing unveils the sludge floccule‐assisted stabilization of aerobic granules in granule‐dominated sequencing batch reactors

Abstract

Floccules are another major form of microbial aggregates in aerobic granular sludge systems. Previous studies mainly attributed the persistence of floccules to their relatively faster nutrient uptake and higher growth rate over aerobic granules; however, they failed to unravel the underlying mechanism of the long-term coexistence of these two aggregates. In this work, the existence and function of the floccules in an aerobic granule-dominated sequencing batch reactor were investigated from the view of quorum sensing (QS) and quorum quenching (QQ).The results showed that though the floccules were closely associated with the granules in terms of similar community structures (including the QS-and QQ-related ones), they exhibited a relatively higher QQ-related activity but a lower QS-related activity. A compatible proportion of floccules might be helpful to maintain the QS-related activity and keep the granules stable. In addition, the structure difference was demonstrated to diversify the QS-and QQ-related activities of the floccules and the aerobic granules. These findings could broaden our understanding of the interactions between the coexistent floccules and granules in aerobic granuledominated systems and would be instructive for the development of the aerobic granular sludge process.

Biofouling Control by Facultative Quorum Quenching Bacteria in Anaerobic Membrane Bioreactors for High-Strength Wastewater Treatment

“…The QQ-related genes, including genes encoding acylase and lactonase (AHLs-degrading enzymes), were mainly found in Methanothrix, Ignavibacterium, and Methanobacterium with abundances of 12.4%, 6.2%, and 3.0%, respectively, in Q-AnMBR (Figure S3b). AHL-based QQ genes, such as K07116 (AHL acylase), K01045 (AHL lactonase), K01055 (AHL lactonase), and K01434 (penicillin amidase, a potential AHL acylase), which could potentially act as an AHLs acylase, 42 exhibited low abundance levels (Figure 6b). The relative abundance of AHL lactonase was relatively low, accounting for 0.004, 0.0069, and 0.0084% in C-AnMBR, V-AnMBR, and Q-AnMBR, respectively.…”