Substrate Preference of Lactonase Shapes the Temporal Dynamics of Complex Microbial Communities

Quorum sensing (QS) is a cell-density-dependent, bacterial intercellular communication system that involves the production, detection, and response of small signaling molecules called autoinducers. A major class of autoinducers is N-acyl homoserine lactone (AHL). AHL varies in their chemical structures, particularly with different acyl chain lengths and C3 substituents, and these different structures modulate the specificity of the signal. Several bacterial behaviors are controlled by QS, including biofilm formation. Recently, disrupting bacterial signaling using enzymes has been shown to effectively inhibit biofilm development and alter microbial community composition and diversity in various environments. However, little has been known about the importance of each signaling molecule in the context of complex microbial communities. Here, we used immobilized quorum quenching lactonases to selectively remove signals in a bioreactor system. Enzymatic signal disruption resulted in both enzymes significantly reducing biofilm formation. Moreover, 16S rRNA sequencing analysis showed that the two lactonases altered the community population structure differentially both in the biofilm and suspension communities in terms of composition, diversity, and abundance of the bacteria. This study provides new and effective tools to investigate the importance of signaling molecules in QS and their roles within the community.