Bacteriocin from Lacticaseibacillus rhamnosus sp. A5: Isolation, Purification, Characterization, and Antibacterial Evaluation for Sustainable Food Processing

Abstract

A new Lacticaseibacillus rhamnosus strain A5 was isolated from pickle soup and characterized for its probiotic suitability. Strain A5 was Gram-positive, catalase-negative, acid-producing, and exhibited potential antibacterial activity against Escherichia coli (inhibition zone 17.3 mm), Bacillus subtilis (inhibition zone 14.5 mm), Salmonella enterica (zone of inhibition 16.1 mm) and Staphylococcus aureus (zone of inhibition 14.2 mm) by performing investigations on the disc diffusion. The cell-free supernatant of newly isolated strain A5 retained its inhibition ability of the growth of test bacteria at pH 2.0 to 5.0, temperature 121 °C for 30 min and UV irradiation for 8 h. However, the inhibitory effects of cell-free supernatant disappeared when subjected to papain, trypsin, and pepsin enzymatic treatments. By eliminating the interferences of organic acid and hydrogen peroxide, the cell-free supernatant possessed antibacterial activity against two indicator bacteria (E. coli and B. subtilis) and showed high thermal tolerance. These results indicated that the antibacterial substances produced by strain A5 were proteinaceous in nature, namely bacteriocin. The antibacterial bacteriocins in the supernatant of the strain A5 culture were further purified by ammonium sulfate fractionation and gel filtration chromatography. The purified bacteriocins also showed a pronounced inhibitory effect against E. coli and B. subtilis. The approximated molecular weight of bacteriocins was less than 14 kDa after determining by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In conclusion, the newly isolated strain A5 and its bacteriocins could be potentially applied in food preservation to prevent the risk of foodborne illness.

Antibacterial activity and mechanism of a novel bacteriocin produced by Lactiplantibacillus plantarum against Escherichia coli and Staphylococcus aureus

“…1a. The absorption peaks at 228 nm and 280 nm in the UV spectrum indicated that the crude extracts consisted of proteins and peptides (Liao et al ., 2017; Biter et al ., 2019), which indicated that crude extracts might be bacteriocin (Ren et al ., 2022). A previous study also indicated that bacteriocins were antimicrobial proteins or peptides produced by lactic acid bacteria that had the potential to combat contamination by pathogenic bacteria in food (Garsa et al ., 2014).…”

Eco-Friendly Microencapsulation of Lacticaseibacillus Paracasei Using Cissampelos pareira Leaf Extract as Natural Encapsulating Materials

“…After incubation at each point, the supernatant (1 mL) was collected, and the bacterium released was determined using the pour plate technique in MRS agar. The index of cell release was calculated by equation (3).…”

“…Recently, the name L. paracasei was changed to Lacticaseibacillus paracasei because the genome diverged from Lactobacillus [2]. It has been demonstrated that bacteria in the genus Lacticaseibacillus are capable of creating bacteriocins, antimicrobial peptides utilized in the food and healthcare industries [3,4]. Unfortunately, factors in the gastrointestinal tract such as low pH, low enzyme levels, and low bile salts make it difficult for free probiotic cells to survive in the body after oral administration.…”

Bio-Preservation of Meat and Fermented Meat Products by Lactic Acid Bacteria Strains and Their Antibacterial Metabolites

“…It has been reported that more than half of almost all bacterial species can produce bacteriocins [66]. In this regard, Ren et al [67] reported the noticeable antibacterial activity of L. rhamnosus sp. A5 against E. coli, B. subtilis, Salmonella, and S. aureus.…”