Signal Disruption Leads to Changes in Bacterial Community Population

Abstract

The disruption of bacterial signaling (quorum quenching) has been proven to be an innovative approach to influence the behavior of bacteria. In particular, lactonase enzymes that are capable of hydrolyzing the N- acyl homoserine lactone (AHL) molecules used by numerous bacteria, were reported to inhibit biofilm formation, including those of freshwater microbial communities. However, insights and tools are currently lacking to characterize, understand and explain the effects of signal disruption on complex microbial communities. Here, we produced silica capsules containing an engineered lactonase that exhibits quorum quenching activity. Capsules were used to design a filtration cartridge to selectively degrade AHLs from a recirculating bioreactor. The growth of a complex microbial community in the bioreactor, in the presence or absence of lactonase, was monitored over a 3-week period. Dynamic population analysis revealed that signal disruption using a quorum quenching lactonase can effectively reduce biofilm formation in the recirculating bioreactor system and that biofilm inhibition is concomitant to drastic changes in the composition, diversity and abundance of soil bacterial communities within these biofilms. Effects of the quorum quenching lactonase on the suspension community also affected the microbial composition, suggesting that effects of signal disruption are not limited to biofilm populations. This unexpected finding is evidence for the importance of signaling in the competition between bacteria within communities. This study provides foundational tools and data for the investigation of the importance of AHL-based signaling in the context of complex microbial communities.

Evaluation of biological and enzymatic quorum quencher coating additives to reduce biocorrosion of steel

“…Yet, reports demonstrate the ability of QQ enzymes, and particularly lactonases, to have a biological effect beyond isolated gram-negative bacterial stains including the inhibition of biofouling [57, 58]. Specifically, the ability of heterologously expressed lactonases to decrease fouling in membrane bioreactors was repeatedly demonstrated [41, 56–58]. In this study, we demonstrated the ability of a purified, extremely stable lactonase to inhibit biocorrosion over a period of 8 weeks in a complex aquatic microbial community.…”

Challenges and Limitations of Anti-quorum Sensing Therapies

“…In another study, it has been shown that lactonase has the modulating effect on the composition of biofilm and planktonic soil microorganisms. The most significant changes were observed for Stenotrophomonas and Pseudomonas (increase), as well as Clostridium cluster XIVa (decrease) (Schwab et al, 2019). Although the experiment was conducted against soil bacteria, these observations indicate the possibility of quantitative changes in microorganisms exposed to factors limiting the QS activity.…”

Effects of Signal Disruption Depends on the Substrate Preference of the Lactonase

“…These enzymes therefore constitute promising candidates to control bacterial virulence and biofilms (Whiteley et al, 2017). Using lactonases may be advantageous to control virulence and biofilm formation over other strategies because these enzymes are not biocidal, and were previously shown to not need contact with bacteria for their activity (Oh et al, 2012;Schwab et al, 2019). Therefore, the risk of resistance (Defoirdt et al, 2010) may be lessened compared to antibiotics (Gerdt and Blackwell, 2014;García-Contreras et al, 2016).…”