• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.1030-1036
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• 2018

Bacillus strains produce various types of antibiotics, and random mutagenesis has traditionally been used to overproduce these natural metabolites. However, this method leads to the accumulation of unwanted mutations in the genome. Here, we rationally designed a single nucleotide substitution in the degU gene to generate a B. subtilis strain displaying increased plipastatin production in a foreign DNA-free manner. The mutant strain (BS1028u) showed improved antifungal activity against Pythium ultimum. Notably, pps operon deletion in BS1028u resulted in complete loss of antifungal activity, suggesting that the antifungal activity strongly depends on the expression of the pps operon. Quantitative real-time PCR and lacZ assays showed that the point mutation resulted in 2-fold increased pps operon expression, which caused the increase in antifungal activity. Likewise, commercial Bacillus strains can be improved to display higher antifungal activity by rationally designed simple modifications of their genome, rendering them more efficient biocontrol agents.

• Korean Journal of Microbiology
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• v.53 no.1
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• pp.55-57
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• 2017

Bacillus subtilis BS16045 was isolated from Gochujang, a Korean red chili paste, in order to get a starter strain that can be used for preservation of the fermented foods. We report the whole genome sequence of B. subtilis BS16045, which contains 4,165,121 bp with a G+C content of 43.6%. We also confirmed the set of antibiotic genes producing surfactin, kanosamine, bacillaene, plipastatin, subtilosin A, and bacilysin, which are related to antifungal and antibacterial activities. These results indicate that B. subtilis BS16045 could be a potential starter strain for solving contamination by food-borne pathogens in the soybean products factory.