Exploring an Efficient and Eco-Friendly Signaling Molecule and Its Quorum Quenching Ability for Controlling Microcystis Blooms

Globally, cyanobacterial blooms have become serious problems in eutrophic water. Most previous studies have focused on environmental factors but have neglected the role of quorum sensing (QS) in bloom development and control. This study explored a key quorum sensing molecule (QSM) that promotes cell growth and then proposed a targeted quorum quencher to control blooms. A new QSM 3-OH-C4-HSL was identified with high-resolution mass spectrometry. It was found to regulate cellular carbon metabolism and energy metabolism as a means to promote Microcystis aeruginosa growth. To quench the QS induced by 3-OH-C4-HSL, three furanone-like inhibitors were proposed based on molecular structure, of which dihydro-3-amino-2-(3H)-furanone (FN) at a concentration of 20 μM exhibited excellent inhibition of M. aeruginosa growth (by 67%). Molecular docking analysis revealed that the inhibitor strongly occupied the QSM receptor protein LuxR by binding with Asn164(A) and His167(A) via two hydrogen bonds (the bond lengths were 3.04 and 4.04 Å) and the binding energy was −5.9 kcal/mol. The inhibitor blocked signaling regulation and induced programmed cell death in Microcystis. Importantly, FN presented little aquatic biotoxicity and negligibly affected aquatic microbial function. This study provides a promising new and eco-friendly strategy for controlling cyanobacterial blooms.