Novel application of L-type phenyllactate in the “three birds one stone” control of Burkholderia gladioli growth and bongkrekic acid production in Auricularia auricula

Burkholderia gladioli is a foodborne pathogen known for its production of toxic metabolites bongkrekic acid (BA). The aim of this study was to investigate a novel application of L-type phenyllactate (L-PLA) in the “three birds one stone” control of B. gladioli growth, biofilm formation, and BA production. The minimum inhibitory concentration and minimum bactericidal concentration of L-PLA against B. gladioli were both 2.0 mg/mL. L-PLA disrupted the integrity and structure of B. gladioli, resulting in leakage of intracellular components and reduction of cell viability. Meanwhile, the accumulation of reactive oxygen species indicated that oxidative stress was involved in the bactericidal mechanism of dissociated B. gladioli. SEM and confocal laser scanning microscope (CLSM) results confirmed the severe destruction of B. gladioli by L-PLA. Additionally, subinhibitory concentrations of L-PLA could effectively inhibit biofilm formation, which was achieved by a decrease in biofilm biomass and a reduction in the proportion of live and dead bacteria within the biofilm. L-PLA demonstrated a notable inhibitory effect on the motility of B. gladioli, accompanied by alterations in cell surface hydrophobicity and auto-aggregation. Furthermore, the synthesis of BA was considerably decreased when exposed to L-PLA stress for 5 d. RT-qPCR showed that the expression of genes involved in BA biosynthesis was suppressed by L-PLA. Notably, bacterial survival rate and BA production of B. gladioli in the Auricularia auricula soaking solution was significantly inhibited with L-PLA (1/2 × -2 × MIC), and did not affect sensory acceptability. Therefore, the present study demonstrates the efficacy of L-PLA as a powerful suppressor of both growth and BA biosynthesis in B. gladioli, aiding in the management and prevention of B. gladioli in food.