Characterization and Optimization of Bacteriocin from <i>Lactobacillus plantarum</i> Isolated from Fermented Beef (Shermout)

Abstract

Many lactic acid bacteria (LAB) were isolated from "Shermout", a popular Sudanese fermented beef product intended for long storage. An isolate that demonstrated significant antibacterial activity was identified as Lactobacillus plantarum PM4 based on phenotypic, physiological and biochemical characteristics and carbohydrate utilization patterns. The inhibitory activity of the partially purified bacteriocin was completely arrested by the proteolytic enzymes proteinase-k and pepsin but not by α-amylase, asserting its proteinaceous nature. The activity was not due to H 2 O 2 as similar inhibition was obtained by cell-free supernatant (CFS) produced under anaerobic conditions. The bacteriocin showed a molecular weight in the range of 3 -5 kDa and had a bactericidal mode of action. No significant reduction in activity was observed on heating to 60˚C for 60 min, but activity was lost on heating to 100˚C or autoclaving. Highest inhibitory activity was at pH 5.5 and there was appreciable reduction in activity at pH 3, 7 or 9. There was no drop in activity at −80˚C or −20˚C up to four weeks of storage. However, at 4˚C and 35˚C, a gradual decline in activity was observed. Lb. plantarum PM4 exhibited bactericidal activity against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli ATCC25922, Klebsiella pneumoniae and Proteus vulgaris. Bacteriocin production generally coincided with the phase of maximum growth and the best combination for maximum production of inhibitory activity was at pH 5.5 for 48 h whether incubated at 25˚C, 30˚C or 37˚C.

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

“…Many Gram-positive and Gram-negative bacteria can secrete substances possessing antibacterial characteristics, called bacteriocins, during their lifecycle [13,14]. Bacteriocins are polypeptides or proteins produced by bacteria that demonstrate antibacterial capabilities against other microbes, which are often genetically close to the producing strain [2,15]. The utilization of these antimicrobial peptides offers a number of advantageous features, such as high efficacy, low possibility to non-specific toxicity or inducing resistance, and the absence of residue generation.…”

Identification and Isolation of Dominant Bacteria in Traditional Isfahan Cheese and Determination if Effective Compounds in Flavor

“…Moreover, Milk is known as one of the richest places of growth of lactic acid bacteria (LAB) (Delavenne et al, 2012;Wouters et al, 2002). Lactic acid bacteria (LAB) are a group of Gram-positive, anaerobic or facultative aerobic, non-sporulating, cocci or rods, and lactic acid is one of the main products of the carbohydrates (Elyass et al 2017;Hayek et al, 2019). Lactic acid bacteria are the main part of bacteria in desirable food fermentations.…”