EVALUATION OF THE ANTIMICROBIAL ACTIVITY OF THE BACTERIAL PROBIOTIC BACILLUS SUBTILIS-534

Objective. To refine the phylogenetic position of and to determine the antimicrobial spectrum and nature of antibiotic activity of the bacterial probiotic Bacillus subtilis-534. Materials and methods. PCR was used to investigate the 16S rRNA gene of strain 534. DNA sequencing was performed using an automatic 3500 Genetic Analyzer and compared with other sequences in the GenBank and Ribosomal Database Project. Antimicrobial activity against 17 test strains was determined in the submerged culture of strain 534 by the agar-diffusion method. The antibiotic was isolated from culture liquid by sorption on an Amberlite XAD-2 resin, by desorption of a mixture of n-butanol-acetone-water, followed by evaporation and dissolution in 60% aqueous ethanol, by injection of the solution into a Kieselgel 60 silica gel column and by stepwise elution with chloroform-methanol solvents. The active fractions were examined by a thin-layer chromatography bioautography method. The UV-absorption spectrum was determined on a UV-1601 PC spectrophotometer. Results. Analysis of DNA sequence of the 16S rRNA gene deposited in the international GenBank under number KU051696 has confirmed that strain 534 belongs to the species Bacillus subtilis. Cultured in vitro, strain 534 suppresses the growth of a number of the strains of Staphylococcus aureus (including MRSA), S. epidermidis, S. haemolyticus, S. hominis, Bacillus pumilis, Micrococcus luteus, Klebsiella рneumoniae, Candida sp., Aspergillus niger, and Saccharomyces cerevisiae. B. subtilis-534 was ascertained to form at least three antibiotics. Conclusion. The bacterial probiotic Bacillus subtilis-534 is the basis of Sporobacterin, shows antibacterial and antifungal activity during submerged cultivation. A chemical assay has indicated the formation of at least three antibiotics, one of which belongs to polyenes, namely: trienes.

Bacillus subtilis 534, probiotics, Bacillus subtilis-534, antibiotic resistance, microbial antagonism, polyenes, trienes