Probiotic potentiality of lactic acid bacteria isolated from Theki Dahi around various places of Pokhara valley

Abstract

This research was undertaken to study the probiotic potentiality of lactic acid bacteria (LAB) isolated from theki dahi around various places of Pokhara valley. A total of 48 samples were collected from different locations, pooled together and finally examined accordingly. Based on the morphological, biochemical and physiological characteristics, three types of Lactobacilli (LAB A, B and C), two types of Leuconostoc (LEU A and B), two types of Bifidobacterium (BIF A and B), one type of streptococci and three types of Lactococci (LCC A, B and C) were identified. Also, probiotic strain of Lactobacillus casei sub sp. Shirota was isolated from yakult sample. All the isolated microbes were then subjected to further examination for probiotic potentiality test and compared to Lactobacillus casei sub sp. Shirota. All the bacteria were found to be Gram positive, catalase-oxidase negative, non-motile bacteria, growing optimally at 30°C (expect Streptococcus thermophilus) and at 0% NaCl. In terms of acid resistance, all of them were found to be resistant to low pH 2 and 4 for 2h with a high resistance of LAB A and BIF B. Similarly, all of them were resistant to bile salt (0.3% and 0.4%) and able to hydrolyze it. Among them, LAB A and BIF B showed high resistance. With regard to antibiotic resistance, all of them were sensitive to penicillin G, ampicillin and amoxicillin but only Lactobacilli and Bifidobacterium showed resistance to ciprofloxacin. Finally, all the isolates were able to adhere to hexane. And, LAB A, BIF A and BIF B showed high hydrophobicity. This study implies that theki dahi comprises variety of LAB with probiotic properties. Statistically, in this study, LAB B and BIF A demonstrated significantly similar probiotic properties (p<0.5) to the control organism. Thus, they can be considered as potential candidate for probiotic organism in theki dahi. This research ultimately helps to document as well as commercialize theki dahi as a potential probiotic food of Nepal.