Forty-four strains of Lactobacillus isolated from fermented milk in different regions were identified by using 16S rRNA gene sequencing. The results showed that the species of these Lactobacillus isolates were Lactobacillus casei, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus helveticus and Lactobacillus bulgaricus. Meanwhile, our present study focused on the susceptibility of these strains to 11 antibiotics from 6 different categories. Our results showed that different Lactobacillus species displayed different resistance to the antibiotics.

A total of 55 strains of Lactobacillus delbrueckii subsp. bulgaricus isolated from traditional fermented milk were separately used for yoghurt production to test their fermentation properties such as fermentation time, post-fermentation acidification, viscosity, syneresis and free amino nitrogen (FAN) concentration. Three strains with desired characteristics, IMAU80319, IMAU20422 and IMAU20404, were selected out of them.