Molecular identification, L-lactic acid production, and antibacterial activity of Bacillus strains isolated from soils

Abstract

Fourteen spore-forming bacteria isolated from soils were evaluated for their taxonomic characterization, lactic acid production, and antimicrobial activity. They were belonged to the genus Bacillus and were closely related to Bacillus coagulans LMG 6326T with 97.48%-98.48% similarity, based on 16S rRNA gene analyses. Repetitive genomic element-PCR (REP-PCR) fingerprinting using the primers sets; BOX-PCR, ERIC-PCR, GTG5-PCR, and REPPCR were used to differentiate among the species. Clustering of the isolates with the PCR fingerprint dendrograms obtained two groups. Group 1 consists of two isolates, JC-3 and JC-11 (14.29%), and the rest of isolates (85.71%) were distributed in another group. Based on 16S rRNA sequence analysis and REP-PCR and the phenotypic characteristics, they were classified as a novel Bacillus species. These isolates were screened for lactic acid production and antimicrobial efficiency, and the results revealed that they produced L-lactic acid in the range of 1.7 ± 0.1 g/l-32.6 ± 0.7 g/l at 98.58% ± 0.06%-100.00% ± 0.00% optical purity. Among them, only JC-19 was found to show inhibitory activity against Kocuria rhizophila ATCC 9341.