Objective Biofilm formation by Pseudomonas fluorescens can accelerate the spoilage of aquatic products and induce food safety risks. The purpose of this study was to screen lactic acid bacteria with excellent inhibitory effects on the biofilm formation of P. fluorescens.

Methods In this study, fermented vegetable samples were first used to isolate lactic acid bacteria. Using P. fluorescens 21F26 as the indicator strain, primary screening was performed via the Oxford cup method, and then rescreening was carried out using the crystal violet staining method. The screened strain was subsequently identified by 16S rDNA sequencing combined with phylogenetic tree analysis, and whole-genome sequencing technology was applied to analyze its genomic information.

Results One strain, designated A21, exhibiting good inhibitory effect on the biofilm of the indicator strain with an inhibition rate of (91.55±3.74)%, was obtained from fermented vegetable samples. This strain was identified as Lactiplantibacillus plantarum. Whole-genome sequencing results showed that the genome of L. plantarum A21 consists of one chromosome (3 220 179 bp) and five plasmids, encoding a total of 3633 genes. Based on the functional gene prediction results, this strain was found to encode 54 secreted proteins, as well as abundant glycoside hydrolases and glycosyl transferases. Three types of secondary metabolite gene clusters were predicted, including cyclic-lactone-autoinducer, terpenes and type Ⅲ polyketide synthases.

Conclusion This study screened out L. plantarum A21, which showed excellent inhibitory activity against the biofilm formation of P. fluorescens. The results could provide theoretical basis for the green and safe prevention and control of P. fluorescens biofilm, and also enrich the resource pool of biofilm inhibitors originating from lactic acid bacteria.