In numerous studies the beneficial impacts of probiotics on human health have been documented. Hence, there is a strong trend for the production of such foods and dairy products in particular, by many of the food processing establishments. In this regard, one of the major perequisites is to recognize the optimum conditions affecting the growth of probiotic organisms. This study aimed to investigate the impact of various concentrations of dextrose, valine, glycine and thiamine as well as

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... t incubation temperatures on growth rate of Lactobacillus acidophillus in steril milk. In order to locate the ideal temperature, L. acidophillus was incubated at 38 °C, 40 °C, 42 °C and 44 °C. Moreover, thiamine (0, 5, 10 and 15 ppm), dextrose (0, 0.4, 0.6, 0.8 and 1%), glycine and valine (0, 30, 60, 90 and 120 ppm) was added to steril milk. The acidity of milk-as an indication of bacterial activity-was measured periodically during 0, 1, 2, 3, 4 and 5 h of incubation. In comparison with the other temperatures, the activity of L. acidophillus was found significantly (P < 0.05) higher at 42 °C. According to the results, addition of dextrose, valine, glycine did not accelerate the production of acidic components; however, it seems that these substances could enhance the potency of L. acidophillus to produce gas and proteolytic enzymes.