Enterococcus faecalis Gr17, a high bacteriocin-producing strain, was isolated from fermented grains of Baijiu. To screen nutritional stress conditions that can positively regulate bacteriocin production and preliminarily explored the specific mechanism of the regulation, the growth and bacteriocin production of the strain under the nutritional stress of 1/4 MRS, 1/2 MRS and 3/4 MRS were measured, and MRS was served as control. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure the expression level of genes related to bacteriocin synthesis in quorum sensing regulation. The results showed the cell growth density decreased with the decrease of initial nutrients, while bacteriocin production of strain Gr17 significantly enhanced under the stress condition of 1/4 MRS. RT-qPCR results showed that under the stress of 1/4 MRS, the expression of bacteriocin structural genes ent I, ent J and ent Gr17, ABC transport system regulatory genes AS-48E, AS-48F, AS-48G and AS-48H, self-induced peptide gene AIP and two-component regulatory genes hpk and rr were significantly increased (P<0.05). Therefore, although nutritional stress is unfavorable to the growth of E.faecalis Gr17, the stress condition of 1/4 MRS can enhance bacteriocin production and quorum sensing system is involved in the regulation. The results provide reference for the research on the regulation mechanism of bacteriocin synthesis under nutritional stress.
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