ABSTRACT:
Lactic acid bacteria are the most important bacteria that have been used as probiotic in food and feed industries. Due to their beneficial probiotic properties, research for new lactic acid bacterial strains is still continued for the new strains which are more tolerable to the stress conditions of the GIT, and have better probiotic properties than the existing strains. In the present study, a total of 33 isolates were obtained from yogurt, cheese and poultry faeces as a potential source for isolation of lactic acid bacteria. Based on the initial identification, 33 isolates which were most probably lactic acid bacteria were selected for in vitro acid and bile tolerance tests. Out of the 33 isolates, 13 isolates were subjected to acid and bile tolerance test and all of them showed good tolerance against acid and bile with more than 80% survival. Identification of 13 selected isolates which exhibited better acid and bile tolerance using 16S rRNA gene sequence analysis showed that all 13 isolates belonged to the genus Lactobacillus including seven L. paracasei, three L. Salivarious, one L. reuteri and one L. casei. Most of the isolates produced significant amount of organic acids, mainly lactic acid. Isolates were then subjected to the antibiotics resistance test and all of them were sensitive to most of the antibiotics except Vancomycin. All the isolated Lactobacillus strains showed good tolerance to acid and bile salts which indicates their survival ability in the GIT, and they might be considered as potential probiotic candidates for both humans and animals. Moreover, considering the production of considerable amounts of organic acids, these strains may have antagonistic activity against pathogenic strains. However, further studies are needed to investigate their probiotic properties including antimicrobial activity.