Isolation and Characterization of Bacteriocin-Producing Lacticaseibacillus rhamnosus XN2 from Yak Yoghurt and Its Bacteriocin

Molecules

Charles Brennan¹  Yonghua Wei²  A.M. Abd El-Aty³  Jinze Wang⁴  Zhe Liu⁴  Jinjin Pei⁴ 

[1] College of Food Science and Engineering, Royal Melbourne Institute of Technology, Melbourne 3046, Australia;College of Food Science, Shanxi Normal University, Taiyuan 030031, China;Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt;Qinba State Key Laboratory of Biological Resources and Ecological Environment, Qinling-Bashan Mountains Bioresources Comprehensive Development C.I.C., Shaanxi Province Key Laboratory of Bio-Resources, College of Bioscience and Bioengineering, Shaanxi University of Technology, Hanzhong 723001, China;

关键词: Lacticaseibacillus rhamnosus;    yak yoghurt;    antibacterial activity;    purification;    bacteriocin;   

DOI  :  10.3390/molecules27072066

来源: DOAJ

【 摘 要 】

Lactic acid bacteria (LAB) produce antimicrobial substances that could potentially inhibit the growth of pathogenic and food spoilage microorganisms. Lacticaseibacillus rhamnosus XN2, isolated from yak yoghurt, demonstrated antibacterial activity against Bacillus subtilis, B. cereus, Micrococcus luteus, Brochothrix thermosphacta, Clostridium butyricum, S. aureus, Listeria innocua CICC 10416, L. monocytogenes, and Escherichia coli. The antibacterial activity was estimated to be 3200 AU/mL after 30 h cultivation. Time-kill kinetics curve showed that the semi-purified cell-free supernatants (CFS) of strain XN2 possessed bactericidal activity. Flow cytometry analysis indicated disruption of the sensitive bacteria membrane by semi-purified CFS, which ultimately caused cell death. Interestingly, sub-lethal concentrations of semi-purified CFS were observed to reduce the production of α-haemolysin and biofilm formation. We further investigated the changes in the transcriptional level of luxS gene, which encodes signal molecule synthase (Al-2) induced by semi-purified CFS from strain XN2. In conclusion, L. rhamnosus XN2 and its bacteriocin showed antagonistic activity at both cellular and quorum sensing (QS) levels. Finally, bacteriocin was further purified by reversed-phase high-performance liquid chromatography (RP-HPLC), named bacteriocin XN2. The amino acid sequence was Met-Lue-Lys-Lys-Phe-Ser-Thr-Ala-Tyr-Val.

【 授权许可】

Unknown