Isolation and identification of lactic acid bacteria from spontaneous whey and curd to be used as potential sources of starter cultures in Yogurt production process

Abstract

The study was conducted to isolate, identify and characterize the lactic acid bacteria present in spontaneous whey and curd. Lactic acid bacteria were isolated from the spontaneous whey and curd samples by serial dilution, and then cultured on MRS agar. The morphological, physiological and biochemical characteristics and sugar fermentation pattern were employed to identify lactic acid bacteria into different genera. The isolates from both whey and curd were identified as rods/cocci. All the isolates were Gram positive, catalase negative and exhibited negative pattern of citrate utilization, indole production, urease activity, NH3 production from arginine. In this study, 13 isolates were obtained from both samples, 6 isolates were rod-shaped and 7 isolated were cocci-shaped. These were categorized as putative genus Streptococci (cocci- shaped) and genus Lactobacillus (rod-shaped). The total bacterial counts of both samples were substantially significant and almost of the same range. The bacterial count in whey ranged from 2.51 × 107 to 1.1 × 109 cfu ml-1 while curd bacterial count ranged from 2.41 × 107 to 1.19 × 109

cfu g-1. This study indicates spontaneous whey and curd as potential sources of lactic acid bacteria which when characterized further to establish their species using the molecular biology technologies and perfected might have an immense potential in producing quality yoghurt.