Lactobacillus plantarum CY 1-1: A novel quorum quenching bacteria and anti-biofilm agent against Aeromonas sobria

Aeromonas sobria is a Gram-negative pathogen with numerous virulence factors that lead to diseases in aquacultures. The production of virulence factors and biofilm formation in A. sobria are regulated by a quorum sensing (QS) system. In this study, we isolated bacterial strain CY 1-1 from pickles with strong quorum quenching activity by screening 154 strains of lactic acid bacteria. Subsequently, we identified it as Lactobacillus plantarum by 16s rRNA sequencing analysis and observed a close to 100% degradation rate for A. sobria-derived N-acyl homoserine lactone. The minimum inhibitory concentration (MIC) of L. plantarum CY 1-1 crude extract (CE) was 4.0 mg/mL. Sub-MICs of 1.0, 2.0, and 3.0 mg/mL L. plantarum CY 1-1 CE showed increased degradation rates for QS-mediated violacein production by Chromobacterium violaceum CV026 and reduced biofilm formation (33.03–81.93%), preformed biofilm (22.01–66.23%), extracellular proteases (17.48–50.56%), haemolytic activity (18.84–53.77%), siderophore (27.49–67.86%), and swarming and swimming (52.49–100%) in a dose-dependent manner. Scanning electron microscopy images indicated that L. plantarum CY 1-1 CE destroyed biofilm structure and reduced the thickness of preformed biofilm. Thus, L. plantarum CY 1-1 CE is a promising QS inhibitor and anti-biofilm agent for improving food safety.