ABSTRACT
The aim of this research was to study on the isolation and characterization of lactic acid producing bacteria in Thailand. Ten bacterial strains isolated from soils and plant bark and root were screened for their lactic acid production. They were divided into 7 groups based on their phenotypic and chemotaxonomic characteristics including 16S rRNA gene sequence analyses. Four isolates in Group I were identified as P. pentosaceus, and each isolate in Group II to Group VII was identified as Enterococcus casseliflavus, E. hirae, Lactobacillus. plantarum, L. paraplantarum, Bacillus coagulans and Sporolactobacillus terrae, respectively. The isolates in Group I, IV, V and VII produced DL-lactic acid ranged from 54.50-77.31 g/L (45.88-75.11% yield) and 0.76-1.07 g/L.h of productivity. The isolates in Group II, III and VI produced optically pure L (+)- lactic acid ranged from 60.72-89.34 g/L (70.00- 74.45% yield) and 0.84-1.24 g/L.h of productivity. B. coagulans isolate in Group VI could produce the highest optically pure L-lactic acid (99.75%).