Analyses of plantaricin Q7 synthesis by Lactobacillus plantarum Q7 based on comparative transcriptomics

Plantaricin Q7 was a bacteriocin with broad-spectrum antibacterial activity and biosafety produced by Lactobacillus plantarum Q7. However, the low yield of plantaricin Q7 was the main limitation to its industrialization. To understand the plantaricin Q7 production at the level of transcription, the biosynthesis of plantaricin Q7 from L. plantarum Q7 was investigated by transcriptomics. It was found that there were four critical time points in plantaricin Q7 synthesis stage. Plantaricin Q7 entered the synthesis period at 2 h, and the largest synthesis rate was observed at 6 h. The highest production of plantaricin Q7 reached at 12 h, and the production began to decrease at 16 h. The transcriptomics results of GO function and KEGG pathway analyses at those four time points showed that oppD encoding ABC oligopeptide transporter, pedC encoding bacteriocin ABC transport accessory protein, agrC encoding histidine protein kinase, and groL as well as groS encoding heat shock protein and accessory protein played a key role in the synthesis of plantaricin Q7. In addition, clpL and clpP encoding protease could cause the degradation of plantaricin Q7. When environmental induction was used to regulate the express of the heat shock protein, plantaricin Q7 yield was increased by 33.33% when 2% NaCl as inducer, and groS was significantly up-regulated. It was suggested that groS could be a critical gene for the synthesis of plantaricin Q7. These findings provided new regulated targets to improve the production of bacteriocins.