Characterization of wild lactic acid bacteria for industrial applications

Abstract

For some decades now, Lactic acid bacteria (LAB) have been an important raw resource in the food and pharmaceutical industries to produce variety of dairy based products including but not limited to cheese, yoghurt, lactic acid. drugs and cosmetics. The LAB strains include the genera of Lactobacillus and Streptococcus. The importation of raw materials such as lactic acid, which can be obtained from indigenous sources, however, affects the foreign exchange of Nigeria's economy greatly. This study was designed to screen, characterize and identify LAB for industrial applications. A total of eighty (80) Lactic Acid Bacteria (LAB) strains were isolated from samples of nunu (a locally fermented milk product) using basic microbiological procedures such as morphological/phenotypic, gram staining, and other biochemical tests. All the isolates were tested for their acidification, curd formation and aroma production abilities. After forty-eight (48) hours of incubation at 42⁰C, twenty-three (23) isolates which satisfied established phenotypic and biochemical criteria were selected for further functional tests. Out of the twenty-three (23) isolates obtained, two (2) strains L53 and L12 had additionally high exopolysaccharide production ability and correspondingly produced yoghurt with high viscosity and very low residual content. Based on the remarkable characteristics obtained from these two species, they are therefore recommended for optimization and proposed for large scale utilization as starter cultures in the dairy industries.