Lactococcus Lactis Strain A5 Producing Nisin-like Bacteriocin Active against Gram Positive and Negative Bacteria

Abstract

In this study, a Lactic acid bacteria (LAB) strain was isolated on MRS medium from gastro-intestinal tissues of Broadhead catfish (Clarias macrocephalus). Out of 50 isolates, 25 isolates were found to be positive on lactose utilisation test and were identified to be gram positive cocci. Using disc diffusion methods, one out of 22 isolates, i.e., a strain A5 demonstrated inhibitions against three indicator organisms; Bacillus cereus, Staphylococcus aureus and Salmonella thyphimurium. Partial 16S rDNA sequencing identified isolate A5 as a member of Lactococcus lactis, with 100% DNA homology. Cell free supernatant fluid from Lactococcus lactis A5 showed inhibitory activities against both gram positive pathogens (Bacillus cereus and Staphylococcus aureus) and gram negative pathogens (Salmonella thyphimurium). Chloroform precipitated bacteriocin retained antagonistic activities in the presence of catalase and lysozyme; and was completely inactivated by Proteinase K treatment. The bacteriocin has a molecular weight of 3.4 kDa, based on SDS-PAGE analysis and the extract was heat stable at 37°C and 65°C, for 15 minutes. The antibacterial activity was suppressed with the addition of EDTA but was significantly increased with the addition of SDS, Triton X-100, Tween 20 and Tween 80. This bacteriocin belongs to class 1 bacteriocin, which was shown to have a nisin-like properties. This strain can be used as potential probiotics in animal or aquaculture feeding; and the bacteriocin it produces will be useful in food preservative.

Bacteriocin production by Lactobacillus plantarum ST16Pa in supplemented whey powder formulations

“…Comparison of the results of Lactobacillus plantarum ST16Pa cultures carried out in shake flasks and bioreactor on the whey powder formulation of run 10 according to the Plackett-Burman experimental design (Table 1 and used as a control, induced a 5.0-mm inhibition zone against L. innocua 6a CLIST 2865, resulting in a synergistic effect of the bacteriocin ST16Pa antimicrobial activity. The same occurrence was noticed by Azhar et al (2017), but in this case the authors reported that SDS caused disaggregation of large molecules present Table 3. Characterization of bacteriocin ST16Pa from bioreactor cell-free supernatants (obtained from the supplemented whey powder formulation corresponding to run 10) in terms of effects of proteolytic enzymes, chemicals, and temperature on the diameter of inhibition zones against Listeria innocua 6a CLIST 2865 1…”

Metabolism Characteristics of Lactic Acid Bacteria and the Expanding Applications in Food Industry

“…Because of its safety to the human body, some bacteriocins have been used in the food industry as bacteriostats and preservatives ( Mulet-Powell et al, 1998 ; Cotter et al, 2005 ; Alvarez-Sieiro et al, 2016b ). Gasserins produced by Lactobacillus gasseri , bacteriocin produced by Lactococcus lactis , and Sakacin P produced by Latilactobacillus sakei have antibacterial activity against Listeria monocytogenes or Bacillus cereus ( Chen et al, 2012 ; Pandey et al, 2013 ; Azhar et al, 2017 ). Lactiplantibacillus plantarum TN8 can inhibit spoilage microorganisms in raw minced beef and extend the shelf life of these products ( Trabelsi et al, 2019 ).…”

Bacterial communities associated with the surface of fresh sweet pepper (Capsicum annuum) and their potential as biocontrol

“…cucumerinum in non-sterile, soil-less potting medium 38 . The bacterial genus Lactococcus, a bacteriocin producing Lactic acid bacteria (LAB), isolated from fresh fruits Chryso-phyllum cainito (star apple) and Solanum stramofolium (pea eggplant), was reported to show inhibitory activities against both Gram-positive pathogens such as Bacillus cereus and Staphylococcus aureus and the Gram-negative pathogens (e.g., Salmonella typhimurium) 39,40 .…”