Abstract
The formation of biofilm can result in membrane biofouling during the operation of a membrane bioreactor (MBR). Biofilm formation is regulated by quorum sensing (QS), and the QS process can be disturbed by quorum quenching (QQ). QQ is considered a promising strategy to mitigate membrane biofouling, and the use of QQ bacteria that possess QQ enzymes has aroused much interest. In this study, we identified a QQ gene (designated as kplD6) from a Klebsiella sp. and expressed the enzyme (KplD6) in Escherichia coli. KplD6 was the first phosphotriesterase-like lactonase identified in Klebsiella, and E. coli expressing KplD6 could effectively mitigate biofouling in MBRs by reducing the transmembrane pressure (TMP) from 35 to 26 kPa. Interestingly, the TMP was further reduced to about 20 kPa in MBRs where γ-caprolactone was added, and γ-caprolactone also enhanced the expression of kplD6 in Klebsiella. Moreover, the addition of E. coli expressing KplD6 or γ-caprolactone to the MBRs had no negative impact on the removal of COD and NH4+-N from the effluent, while exerting only a little effect on the relative abundance of the dominant phyla in the MBR. These findings have shed further light on the application of QQ via Klebsiella sp. in the mitigation of biofouling in MBRs.
Published Version
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