Antimicrobial Characteristics of Lactic Acid Bacteria Isolated from Homemade Fermented Foods

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.

Insights Into The Broad Antibacterial Spectrum Of Bacteriocin Isolated From Probiotic Lactobacillus Fermentum LMEM22 Strain

“…bacteria, demonstrating a decrease of antibacterial action with proteinase K and pronase treatment of the bacteriocin, but not due to α-amylase treatment. The bacteriocins of L. plantarum, L. pentosus and L. paracasei displaying growth inhibitory effect against Salmonella and S. aureus with ZDIs 13.08±0.15-15.22±0.13 mm, lost their antimicrobial action after treatment with proteolytic enzymes (proteinase K, pepsin, and papain), as has been reported by Ren et al (2018). In the current study, on enzymatic treatment with proteinase K and trypsin, the L. fermentum LMEM22 bacteriocin activity has been found to be decreased when tested against grampositive (Staphylococcus aureus and Listeria monocytogenes) as well as gram-negative (Acinetobacter baumannii and Escherichia coli) indicator bacteria, and the bacteriocin was found insensitive against αamylase activity, authenticating its proteinaceous nature, which was in accordance to the report of the earlier authors (Ge et al, 2016;Fahim et al,, 2017).…”

Meat starter cultures: Isolation and characterization of lactic acid bacteria from traditional sausages

“…Concerning Gram-positive bacteria, the most suppressive effect was detected in the case of Staphylococcus aureus, with a large inhibition zone of 16.63 mm in the case of the CCP 10-1/1 iso-late. The characterized LAB isolates from sausages exerted greater inhibitory effect against S. aureus in contrast with bacterial isolates from home-made fermented foods (Ren et al, 2018). In the case of the two Bacillus strains, the inhibition zone ranged between 11.40 and 14.40 (B. cereus) and between 8.6 and 14.53 (B. subtilis).…”

Novel probiotic lactic acid bacteria isolated from indigenous fermented foods from West Sumatera, Indonesia

“…Ren et al . [ 32 ] found that Lactobacillus T8 produced antibacterial substances belonging to a protein family, and its zone of inhibition against pathogens significantly increased (>13 mm) after these substances were produced. Obdak et al .…”