Improving 3-phenyllactic acid production of Lactobacillus plantarum AB-1 by enhancing its quorum-sensing capacity.

3-Phenyllactic acid (PLA) is a novel and natural antimicrobial compound. However, the concentration of PLA produced by native microbes was rather low. To enhance the production of PLA of Lactobacillus plantarum AB-1, the microcapsules of L. plantarum AB-1 cells with a high quorum-sensing capacity was established and investigated. In addition, the relation between PLA production and quorum sensing was further investigated and confirmed by adding the exogenous 4,5-dihydroxy-2,3-pentanedione (DPD, AI-2 precursor). The results indicated that the PLA production of L. plantarum AB-1 in microencapsulated cells (MC cells) was higher than that of the free cells, and the lactate dehydrogenase activity, autoinducer-2 (AI-2) levels and the relative expression of the luxS gene were also significantly increased in MC cells (P < 0.05). In addition, the cell growth, AI-2 levels and PLA production of L. plantarum AB-1 were also significantly promoted after adding 24 μM exogenous DPD. The results suggest that the PLA production of L. plantarum was partly regulated by the AI-2/LuxS system, and microencapsulation can increase the local AI-2 level and enhance QS capacity, which are beneficial to PLA production. The results may provide a new insight and experimental basis for the industrial production of PLA.