The ldh Gene Plays a Crucial Role in Mediating the Pathogen Control of Lactiplantibacillus plantarum AR113.

Effectively managing foodborne pathogens is imperative in food processing, where probiotics play a crucial role in pathogen control. This study focuses on the Lactiplantibacillus plantarum AR113 and its gene knockout strains, exploring their antimicrobial properties against Escherichia coli O157:H7 and Staphylococcus aureus. Antimicrobial assays revealed that the inhibitory effect of AR113 increases with its growth and the potential bacteriostatic substance is acidic. AR113Δldh, surpassed AR113Δ0273&2024, exhibited a complete absence of bacteriostatic properties, which indicates that lactic acid is more essential than acetic acid in the bacteriostatic effect of AR113. However, the exogenous acid validation test affirmed the equivalent superior bacteriostatic effect of lactic acid and acetic acid. Notably, AR113 has high lactate production and deletion of the ldh gene not only lacks lactate production but also affects acetic production. This underscores the ldh gene's pivotal role in the antimicrobial activity of AR113. In addition, among all the selected knockout strains, AR113ΔtagO and ΔccpA also had lower antimicrobial effects, suggesting the importance of tagO and ccpA genes of AR113 in pathogen control. This study contributes insights into the antimicrobial potential of AR113 and stands as the pioneering effort to use knockout strains for comprehensive bacteriostatic investigations.