Isolation, Identification and Analysis of Probiotic Properties of Lactobacillus Spp. From Selective Regional Yoghurts

Yoghurt is a potential source of probiotic lactobacilli. In the present study, Lactobacillus spp. were isolated from two regional yoghurts in Bangladesh, which were identified on the basis of their colony morphologies and some biochemical tests. It was observed that isolated Lactobacillus spp. were resistance to inhibitory substances like phenol (0.4%), NaCl (1-9%) and bile acid (0.05-0.3%). Additionally, good growths were observed in the presence of 1% NaCl and 0.3% bile acid. The isolated Lactobacillus spp. did show good survival abilities in acidic (pH 2.5) and alkaline (pH 8.5) conditions, while, their maximum growth was observed at pH 5.0 for lactobacilli isolated from Bogra yoghurt and at pH 6.5 for lactobacilli isolated from yoghurt of Khulna region of Bangladesh. Isolated lactobacilli were able to produce organic acid in skim milk which was determined by titrimetric method. The Lactobacillus spp. also did show good survival abilities in simulated gastric juice at pH 2.22 and pH 6.6 (Control). Their susceptibility to selected nine antibiotics was determined in terms of minimum inhibition concentration (MIC). The MICs results showed that, Lactobacillus spp. isolated from Bogra yoghurt were sensitive to amoxicillin, moderately sensitive to gentamycin, clindamycin, azithromicin and resistant to kanamycin, nalidixic acid, metronidazol, cefradine and tetracyclin. On the other hand, Lactobacillus spp. isolated from yoghurt of Khulna region were sensitive to gentamicin, clindamicin and resistant to amoxicillin, tetraciclin, kanamicin, nalidixic acid, metronidazol, azithromicin and cefradine. In conclusion, most of the results from the present experiments showed that, there were variations in probiotic properties of the isolated Lactobacillus spp. from different regions.