Abstract
Objective. Lactic acid bacteria (LAB) were isolated from fermented foods, such as glutinous rice dough, corn noodle, chili sauce, potherb mustard pickles, and stinky tofu, in northeast China. LAB strains with antimicrobial activities were screened, and seven of these Lactobacillus strains were identified as L. plantarum, L. pentosus, and L. paracasei through 16S rRNA gene analysis. After the supernatant of LAB was treated with proteinase K, pepsin, and papain, their antibacterial effect almost disappeared. Most strains with antibacterial activities were highly resistant to heat (65°C–121°C), acidity (pH 2–6), and alcohol. The antimicrobial effect of most strains treated with the Tween-80 surfactant was significantly reduced, and the antibacterial property of T4 was even lost. Ammonium sulfate precipitation, PCR, and nanoLC-ESI-MS/MS results confirmed that T8 produced antibacterial substances belonging to a protein family, and its zone of inhibition against pathogens significantly increased (>13 mm). In bacterial growth inhibition experiments, the colony count of Staphylococcus aureus was up to 1015 CFU/mL in the 3⁎de Man, Rogosa, and Sharpe (MRS) group, and this value was more than that in the 3⁎S6 supernatant group (1012 CFU/mL) and the control group (1010 CFU/mL) at 12 h. This study provided a basis for the selection of antimicrobial peptides and the development and utilization of LAB.
Highlights
Food-borne diseases associated with the consumption of fresh and minimally processed agricultural products have resulted in remarkable outbreaks and caused health problems
The preliminary effect of the antimicrobial activity of the strains was determined via the diffusion method with 1 M HCl/NaOH to remove the acid that could inhibit the production of pathogenic bacteria in the supernatant
In vitro studies showed that the antibacterial components of seven lactic acid bacteria (LAB) isolated from nianmianzi, tangzimian, chili sauce, potherb mustard pickles, and stinky tofu were resistant to certain temperature ranges (65∘C–121∘C), acidity, alcohol, and some additives
Summary
Food-borne diseases associated with the consumption of fresh and minimally processed agricultural products have resulted in remarkable outbreaks and caused health problems. The side effects of the improper use of artificial preservatives and antibiotics have become serious. Traditional sterilization methods involve the use of chemical sanitizers or high-temperature heating sterilization. In this way, harmful bacteria are incompletely eradicated, and organoleptic qualities decline [1]. In vitro analysis found that lactic acid bacteria (LAB) have antioxidant effects and can chelate ferrous ions and degrade nitrite and cholesterol [3, 4]. LAB are natural microbes, and their metabolites are generally regarded as safe [5]
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