The β-galactosidase LacLM plays the major role in lactose utilization of Lactiplantibacillus plantarum

Lactiplantibacillus plantarum has often been used for fermentation of lactose-rich substrates. However, its growth in lactose has not been studied at the molecular level and the role of different beta-galactosidases is also unknown. In this study, transcriptome sequencing was performed to reveal the difference of gene expression when Lp. plantarum LP01 was cultivated in glucose and lactose medium. Two genetic loci involved in lactose metabolism were highly transcripted by lactose induction, in which beta-galactosidase coding gene lacA, lacL and lacM were upregulated by 9.86, 9.12 and 9.53-fold, respectively. To explore the detail role of different beta-galactosidase, mutant strains Lp. plantarum Delta lacA, Lp. plantarum Delta lacLM and Lp. Plantarum Delta lacA Delta lacLM was constructed by gene knockout. Results showed that the growth of Lp. plantarum.lacA was slightly weakened in lactose medium, while the growth of Lp. plantarum Delta lacLM and Lp. plantarum Delta lacA Delta lacLM was completely inhibited. Furthermore, the growth of Lp. plantarum Delta lacLM could be restored after transformed into an complementation vector pNZ8148-PlacLM-lacLM. Therefore, the beta-galactosidase LacLM plays the major role in lactose utilization of Lp. plantarum, providing a theoretical foundation for the growth and metabolism of Lp. plantarum in lactose medium.

Automated summary

Transcriptome sequencing revealed the gene expression difference of Lactiplantibacillus plantarum in glucose and lactose medium, identifying that beta-galactosidase LacLM plays a major role in lactose utilization, providing a theoretical foundation for the growth and metabolism of Lp. plantarum in lactose medium.