Selected properties of lactic acid bacteria isolated from raw cow's milk

For the identification of lactic acid bacteria derived from raw cow's milk, 151 colonies were isolated. The grow conditions of lactic acid bacteria were at temperature 37 °C for 3 days on MRS medium. Based on microscopical preparation, negative catalase and Gram-positive test were 81 isolates confirmed as genus Lactobacillus. Out of these, 9 isolates were evaluated for acidifying activity in UHT milk at 25 °C, 30 °C and 37 °C at regular intervals during 24 hours. The average count of NSLAB lactobacilli in raw cow's milk reached the value 1.54.104 KTJ.ml-1. It was found that all tested strains of lactobacilli did not cause significant changes of titratable acidity in milk at 25 °C and 30 °C. Only one strain significantly improved the titratable acidity of milk at 37 °C after 24 hours. The acidity reached the value from 7.5 °SH to 41.9 °SH. This strain was confirmed by PCR method as Lactobacillus helveticus