• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1033-1042
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• 2019

Bacillus velezensis BS2 was isolated from meongge (common sea squirt) jeotgal, a Korean fermented seafood, and produces a bacteriocin, BacBS2, which strongly inhibits Listeria monocytogenes and Bacillus cereus. BacBS2 was partially purified by Q-Sepharose column chromatography after ammonium sulfate precipitation of the culture supernatant, then further purified by Sephadex G-50 column chromatography. Partially purified BacBS2 was estimated to be 6.5 kDa in size by Tricine-SDS PAGE and activity detection by gel-overlay. Enzyme treatment and FT-IR spectrum of partially purified BacBS2 confirmed its proteinaceous nature. BacBS2 was fully stable at pH 4-9, and half of activity was retained at pH 1-3. Full activity was retained after exposure to $80^{\circ}C$ for 15 min, but half of the activity was retained upon exposure to $90^{\circ}C$ for 15 min or $100^{\circ}C$for 10 min. BacBS2 inhibited L. monocytogenes by bactericidal mode of action. B. velezensis BS2 and its BacBS2 seem useful as biopreservatives for fermented foods such as jeotgal.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.342-343
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• 2017

Bacillus velezensis T20E-257 was isolated from the root tissue of a tomato plant and exhibited plant growth-promoting activity. Here we present the complete genome of strain T20E-257. The genome contains 3,900,066 base pairs with a G + C content of 46.7% in 2 contigs. The genome includes 3,708 coding sequences, 27 rRNAs, and 86 tRNAs. We found gene clusters encoding secondary metabolites with an antimicrobial activity and genes related to the production of indole-3-acetic acid and 2,3-butanediol, which play a role in plant growth and health.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.347-356
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• 2019

Bacillus sp. BS2 showing strong fibrinolytic activity was isolated from sea squirt (munggae) jeotgal, a traditional Korean fermented seafood. BS2 was identified as B. velezensis by molecular biological methods. B. velezensis BS2 grows well at 15% NaCl and at $10^{\circ}C$. When B. velezensis BS2 was cultivated in TSB broth for 96 h at $37^{\circ}C$, the culture showed the highest fibrinolytic activity ($131.15mU/{\mu}l$) at 96 h. Three bands of 27, 35 and 60 kDa were observed from culture supernatant by SDS-PAGE, and fibrin zymography showed that the major fibrinolytic protein was the 27 kDa band. The gene (aprEBS2) encoding the major fibrinolytic protein was cloned, and overexpressed in heterologous hosts, B. subtilis WB600 and E. coli BL21 (DE3). B. subtilis transformant showed 1.5-fold higher fibrinolytic activity than B. velezensis BS2. Overproduced AprEBS2 in E. coli was purified by affinity chromatography. The optimum pH and temperature were pH 8.0 and $37^{\circ}C$, respectively. $K_m$ and $V_{max}$ were 0.15 mM and $39.68{\mu}M/l/min$, respectively, when N-succinyl-Ala-Ala-Pro-Phe-pNA was used as the substrate. AprEBS2 has strong ${\alpha}$-fibrinogenase and moderate ${\beta}$-fibrinogenase activity. Considering its high fibrinolytic activity, significant salt tolerance, and ability to grow at $10^{\circ}C$, B. velezensis BS2 can be used as a starter for jeotgal.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.520-524
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• 2009

Two isolates, Bacillus sp. BS87 and RK1, selected from soil in strawberry fields in Korea, showed high levels of antagonism towards Fusarium oxysporum f. sp. fragariae in vitro. The isolates were identified as B. velezensis based on the homology of their gyrA sequences to reference strains. BS87 and RK1 were evaluated for control of Fusarium wilt in strawberries in pot trials and field trials conducted in Nonsan, Korea. In the pot trials, the optimum applied concentration of BS87 and RK1 for pre-plant root-dip application to control Fusarium wilt was $10^5$ and $10^6$ colony-forming units (CFU)/ml, respectively. Meanwhile, in the 2003 and 2005 field trials, the biological control efficacies of formulations of RK1 were similar to that of a conventional fungicide (copper hydroxide) when compared with a non-treated control. The RK1 formulation was also more effective than BS87 in suppressing Fusarium wilt under field conditions. Therefore, the results indicated that formulations of B. velezensis BS87 and RK1 may have potential to control Fusarium wilt in strawberries.

• The Plant Pathology Journal
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• v.37 no.3
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• pp.307-314
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• 2021

Pepper (Capsicum annuum L.) is an important agricultural crop worldwide. Recently, Colletotrichum scovillei, a member of the C. acutatum species complex, was reported to be the dominant pathogen causing pepper anthracnose disease in South Korea. In the present study, we isolated bacterial strains from rhizosphere soil in a pepper field in Gangwon Province, Korea, and assessed their antifungal ability against C. scovillei strain KC05. Among these strains, a strain named BS1 significantly inhibited mycelial growth, appressorium formation, and disease development of C. scovillei. By combined sequence analysis using 16S rRNA and partial gyrA sequences, strain BS1 was identified as Bacillus velezensis, a member of the B. subtilis species complex. BS1 produced hydrolytic enzymes (cellulase and protease) and iron-chelating siderophores. It also promoted chili pepper (cv. Nockwang) seedling growth compared with untreated plants. The study concluded that B. velezensis BS1 has good potential as a biocontrol agent of anthracnose disease in chili pepper caused by C. scovillei.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.359-363
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• 2019

Meju is a spontaneously fermented soybean product produced in Korea. We isolated the bacteria of the genera Bacillus, Enterococcus, and Staphylococcus from 12 meju samples collected from five regions of Korea using selective media, and we identified them based on the sequence analysis of 16S ribosomal RNA and gmk (guanylate kinase) genes. Bacillus and Enterococcus strains were identified from all samples and the numbers of Bacillus strains in the 11 samples were >15% of the total cell number. Therefore, the genus Bacillus was confirmed as the predominant bacterial group of meju. Staphylococcus strains were identified from six samples. The identified 151 Bacillus isolates predominated in the following order: B. velezensis, B. sonorensis, B. subtilis, and B. licheniformis. Among the 165 Enterococcus isolates, 163 strains were identified as E. faecium. Eighty-two Staphylococcus isolates were classified into six species of coagulase-negative Staphylococcus group and S. xylosus was the predominant species.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.580-595
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• 2021

Although late blight is an important disease in ecofriendly potato cultivation in Korea, it is highly dependent on the use of eco-friendly agricultural materials and the development of biological control technology is low. It is a necessary to develop an effective biocontrol agent to inactivate late blight in the field. AFB2-2 strain is a gram-positive with peritrichous flagella. It can utilize 20 types of carbon sources, like L-arabinose, and D-trehalose at 35℃. The optimal growth temperature of the strain is 37℃. It can survive at 20-50℃ in tryptic soy broth. The maximum salt concentration tolerated by AFB2-2 strain is 7.5% NaCl. AFB2-2 strain inhibited the mycelial growth of seven plant pathogens by an average inhibitory zone of 10.2 mm or more. Among the concentrations of AFB2-2, 10⁷ cfu/ml showed the highest control value of 85.7% in the greenhouse. Among the three concentrations of AFB2-2, the disease incidence and severity of potato late blight at 10⁷ cfu/ml was lowest at 0.07 and 6.7, respectively. The nucleotide sequences of AFB2-2 strain were searched in the NCBI GenBank; Bacillus siamensis strain KCTC 13613, Bacillus velezensis strain CR-502, and Bacillus amyloliquefaciens strain DSM7 were found to have a genetic similarity of 99.7%, 99.7%, and 99.5%, respectively. The AFB2-2 strain was found to harbor the biosynthetic genes for bacillomycin D, iturin, and surfactin. Obtained data recommended that the B. velezensis AFB2-2 strain could be considered as a promising biocontrol agent for P. infestans in the field.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.111-119
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• 2021

A bacterial strain isolated from a Malva verticillata leaf was identified as Bacillus velezensis MV2 based on the 16S rRNA sequencing results. Complete genome sequencing revealed that B. velezensis MV2 possessed a single 4,191,702-bp contig with 45.57% GC content. Generally, Bacillus spp. are known to produce diverse antimicrobial compounds including bacteriocins, polyketides, and non-ribosomal peptides. Antimicrobial compounds in the B. velezensis MV2 were extracted from culture supernatants using hydrophobic interaction chromatography. The crude extracts showed antimicrobial activity against both gram-positive bacteria and gram-negative bacteria; however, they were more effective against gram-positive bacteria. The extracts also showed antifungal activity against phytopathogenic fungi such as Fusarium fujikuroi and F. graminearum. In time-kill assays, these antimicrobial compounds showed bactericidal activity against Bacillus cereus, used as indicator strain. To predict the type of antimicrobial compounds produced by this strain, we used the antiSMASH algorithm. Forty-seven secondary metabolites were predicted to be synthesized in MV2, and among them, fourteen were identified with a similarity of 80% or more with those previously identified. Based on the antimicrobial properties, the antimicrobial compounds may be nonribosomal peptides or polyketides. These compounds possess the potential to be used as biopesticides in the food and agricultural industry as an alternative to antibiotics.

• Fisheries and Aquatic Sciences
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• v.22 no.8
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• pp.17.1-17.9
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• 2019

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

• The Korean Journal of Mycology
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• v.40 no.2
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• pp.118-123
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• 2012

In order to develop environment friendly fungicide for the control of citrus green mold (Penicillium digitatum) using endophytic bacteria, the 21 bacterial isolates were isolated from citrus leaves in seven different orchards in Jeju Province. Among the 21 bacterial isolates, 5 bacterial isolates presented antifungal activity against green mold pathogen P. digitatum. The CB3 isolate, which showed the most strong antagonistic effect, was selected through opposite culture against the pathogen. The rod-shaped, gram-positive bacterium CB3 was identified as Bacillus velezensis based on morphological, physiological characteristics, 16S rDNA, and gyr A gene sequence analysis. The isolate CB3 showed strong antifungal activity against two citrus postharvest pathogen P. digitatum. Citrus fruits were treated by wound inoculation with P. digitatum pathogen, and the control efficacy of CB3 culture broth was 66.7% ($1{\times}10^8$ cfu/ml). In conclusion, The stability of CB3 and its strong antifungal activity also lead us to believe that it has potential for application as an environment friendly biological control agent.