Advancing aquaculture probiotic discovery an innovative protocol for selective isolation of indigenous, stress tolerant probiotic candidates displaying enhanced quorum quenching

Pathogenic bacteria use quorum sensing (QS) to regulate virulence gene expression and enhance antimicrobial resistance (AMR) via cell-cell communication with autoinducers (AIs) such as N-Acyl Homoserine Lactones (AHLs) (Defoirdt, 2018). However, the disruption of QS, known as quorum quenching (QQ), can inhibit virulence gene activation and alter bacterial infectious cycles, thereby controlling diseases caused by such pathogens (LaSarre & Federle, 2013). Unlike bactericidal antibiotics, QQ does not significantly affect bacterial growth, minimizing selective pressure for AMR phenotypes, making it a promising antivirulence approach (Ghanei-Motlagh et al., 2021a). As highlighted by Kuebutornye et al. (2019), certain groups of bacteria, such as Bacillus spp., were demonstrated to have a high probiotic potential in aquaculture, which also exhibit QQ properties. Probiotics, are live microorganisms that offer various benefits such as enhanced immunity and resistance to pathogens (El-Saadony et al., 2021). With increasing concerns on the use of antimicrobial agents in aquaculture, probiotic bacteria emerge as one of the safer alternatives (Lu et al., 2022; Serwecinska, 2020). Hence, bacteria with indigenous QQ systems that are adapted to local conditions (e.g., tolerance to salt water) would offer inherent tolerance to environmental stressors and may exhibit improved efficacy against local and emergent aquaculture pathogen.