Characterization of Listeria-active bacteriocin produced by a new strain Lactobacillus plantarum subsp. plantarum SKI19 isolated from “sai krok e-san mu”
2018
Upaichit, A. | Botthoulath, V. | Thumarat, U.
Bacteriocin produced by Lactobacillus plantarum subsp. plantarum SKI19 was harvested for purification during early stationary phase (optimum bacteriocin production). Purification of bacteriocin SKI19 was achieved by ammonium sulfate precipitation at 60% saturation followed by SP-Sepharose Fast Flow column. The molecular mass of bacteriocin SKI19 determined by Tricine-SDS-PAGE analysis was estimated to 2.5 kDa. Physical and biochemical studies revealed that purified bacteriocin SKI19 was heat-stable even after autoclaving at 121°C for 15 mins, and was active over a wide pH range (2.0-10.0). A reduction in antibacterial activity was observed after treatment of the bacteriocin SKI19 with proteolytic enzymes (α-chymotrypsin, trypsin, proteinase K, and pronase E), confirming that bacteriocin SKI19 is proteinaceous innature. When viewed under SEM, cell membranes of the indicator strain appeared to collapse after exposure to bacteriocin SKI19. It was found that bacteriocin SKI19 inhibited not onlyclosely related species, but was also effective against Listeria monocytogenes DMST 17303. Moreover, complete inhibition (L. monocytogenes DMST 17303) or significant inhibition(Escherichia coli DMST 4212, and Staphylococcus aureus DMST 8840) by SKI19 was observed in co-cultivation under anaerobic conditions. The results suggest that bacteriocinSKI19 as well as the direct use of SKI19 as a starter culture might be applied as biocontrol agents to improve the shelf-life of certain food products.
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