The present work aimed to assess the stresses of temperature, salt concentration, and pH on Lactobacillus gasseri 54C, Lactiplantibacillus plantarum ATCC 14917, and 11SH in fermented culture medium and their effects on interleukin-12 (IL-12) induction in murine splenocytes. First, the strains were fermented under different microbial stress conditions at salt concentrations (2, 4, and 6 % w/v), temperatures (30 and 42 ◦C), and pH levels (4, 5, and 6), as well as their combined conditions. Then, they were heat-killed, lyophilized, and exposed to murine splenocytes. The IL- 12 induction was measured using the immunoassay method. It was indicated that the induction of IL-12 depended on the culture conditions, as it was increased by the fermentation strains under microbial stresses with the higher temperature (42 ◦C), lower salt concentration (%2), and lower pH level (4). It seems that the bacterial cells’ integrity is essential to stimulate the induction of IL- 12.

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