A broad-spectrum novel bacteriocin produced by Lactobacillus plantarum SHY 21-2 from yak yogurt: Purification, antimicrobial characteristics and antibacterial mechanism

This research aimed to find a natural biological preservative that inhibits harmful bacteria in the food production process. We screened a bacteriocin-producing Lactobacillus plantarum SHY 21-2, which was isolated from yak yogurt. The bacteriocin was purified by salting out, AKTA purifier 10 and reversed-phase high-performance liquid chromatography (RP-HPLC). The LC-MS/MS analysis revealed that the molecular weight of bacteriocin was 1362.84 Da and the predicted the amino acid sequence was RPNEPRLLLPR. This strain produced a novel IId bacteriocin and named plantaricin LP 21-2. LP 21-2 was heat-resistant and still had 96% antibacterial activity after being exposed to 121 degrees C for 15 min. LP 21-2 had obvious antibacterial activity at pH 2-5 and could be completely inactivated by pepsin, trypsin, and papain. LP 21-2 had a broad antimicrobial spectrum against on Gram-positive bacteria, Gram-negative bacteria and fungi, including Staphylococcus aureus ATCC25923, Salmonella typhi CMCC50071 and Saccharomyces cerevisiae ATCC9763. The minimal inhibitory concentration (MIC) of LP 21-2 on Staphylococcus aureus ATCC 25923 was 0.18 mg/ml. Analyzed by scanning electron microscopy and transmission electron microscopy, LP 21-2 induced pore formation in cell membranes and caused cytoplasmic leakage to kill bacteria. These results indicate that plantaricin LP 21-2 has potential as a bioprotective agent in food.

Automated summary

This study identified a novel IId bacteriocin named plantaricin LP 21-2 produced by Lactobacillus plantarum SHY 21-2 isolated from yak yogurt. LP 21-2 demonstrated strong antibacterial activity against a wide range of bacteria and fungi, showing potential as a bioprotective agent in food industry.