Isolation and evaluation of lactic acid production content in native Lactobacillus of Chaharmahal va Bakhtiari province isolated from dairy products

the use of lactic acid bacteria in fermented dairy products due to their effects participation in flavor، texture and most probiotic properties goes back to centuries ago. Optimal amount of lactic starter culture in the production of lactic acid in the production of cheese and yogurt are used. Isolation of Lactobacillus in MRS medium from various samples was performed. Then، The variation of different characteristics in terms of the ability of Lactobacilli to produce CO2 from glucose، the ability to grow at pH 2. 5 to 8. 5، different concentration of NaCl، 1. 5 to 10. 0 (percent w / v) and temperatures of 15 ° c، 45° c، the ability to move، indole and H2S production were also studied. The production of lactic acid was assayed in skim milk by titration with %1 NaOH. L-lactate isomer was investigated using UK Randox kit. In this study، from 30 samples of different indigenous yoghurt and cheese 43 gram-positive، catalase-negative، oxidase negative lactobacilli were isolated. All isolates were resistant to pH 2. 5 and 30 and %69 of the isolated were sensitive to 7. 5 and %10 concentration of salt respectively. Most of lactic acid production with % 1. 8 and L-lactate 6. 8 g/l were consididered for one isolated. This isolated bacillus based on biochemical tests was identified as Lactobacillus acidophilus. Discussion and The amount of lactic acid production at temperature 37°C was found to be higher than the temperature 25°C criteria that were statistically significant at %1 level. The optimal production of lactic acid in the native isolates and tolerance to appropriate pH and salt tolerance، these properties and studies are provided complementary knowledge to be used in the food industry.