APPLICATION OF LACTOBACILLUS CASEI AND TEMPERATURE TO CONTROL OF SALMONELLA TYPHIMURIUM UNDER IN VITRO CONDITIONS

There is a strong inclination and attention toward consumption of functional foods due to their bioprotection in preventing health problems and conferring health benefits beyond their nutritional content. The aim of this study was to evaluate L. casei potential as bioprotection and probiotic agent to inhibit s. Typhimurium. For this purpose, firstly, the antibacterial capacities towards s. Typhimurium were determined in an agar spot test. Secondly, in macrodilution method, several dose of L. casei was evaluated for its effects on the growth and survival of s. Typhimurium inoculated onto mixture broth media (LB+ MRS broth). In Agar spot test, inhibition zone diameter of s. Typhimurium in encounter with 6.6 and 2.6 log of L.casei for the first and third day were 23.96, 15.74, 25.78, and 17.19 (mm) respectively. At 8-10 and 37 ° C, initial counts of s. Typhimurium in the mixture broth media treated with 8 log of L. casei decreased from ~5 to 2 and undetected level (<1 log CFU/ml) respectively at final day. With 5 log of L.casei, it reached from ~5 to 5.5 and below the detection level (˂ 1 log CFU/ml) respectively as well. But 3 log of L. casei did not effect on this level of s. Typhimurium compared with control in which just s. Typhimurium was available in the mixture broth media. L. casei was more effective in reducing s. Typhimurium population at 37 ° C than 8-10 ° C. Besides, Log 8 of L. casei caused a higher reduction in initial s. Typhimurium counts compared to other low level of them. The mixed broth media with high dose of L.casei had also the lowest pH value among the others.