• The Korean Journal of Mycology
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• v.47 no.4
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• pp.417-425
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• 2019

Biocontrol agents (BCAs) are widely used to protect plants from diverse biotic and abiotic stresses in agricultural and ecological fields. Among the various microbes, many subspecies of the gram-positive genus, Bacillus, have been successfully industrialized as eco-friendly biological pesticides and fertilizers. In the current study, we demonstrated that Bacillus thuringiensis C25 exhibited antagonistic effects on the mycelial growth of Rosellinia necatrix, a fungal phytopathogen. Scanning electron microscopy analysis revealed that B. thuringiensis C25 degraded the cell wall structures of R. necatrix mycelia. In the functional genomic analysis of B. thuringiensis C25, we annotated 5,683 genes and selected the gene sets that potentially encoded fungal cell wall degrading enzymes (CWDEs). The growth inhibition effects on R. necatrix were highly correlated with the transcriptional activity of the mycelial cell wall degrading genes of B. thuringiensis C25. The transcript levels of CWDEs, including CshiA, B, and Glycos_transf_2 genes in B. thuringiensis C25, were enhanced following co-cultivation with R. necatrix. In conclusion, our study suggested that B. thuringiensis C25 could serve as a suitable candidate for controlling R. necatrix and could facilitate elucidating the mechanisms underlying the antifungal activities of BCAs against phytopathogens.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.216-218
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• 2017

We here provide the complete genome sequence of Bacillus thuringiensis C25, the strain showing antagonistic effects on fungal phytopathogens. The genome comprised of 5,308,062 bp with 35.32% G+C content of a circular chromosome and a plasmid containing 308,946 bp with 32.23% G+C content. The chromosome and plasmid genome included 5,683 protein coding DNA sequences, 107 tRNA and 42 rRNA genes.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.250-254
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• 2007

Bacillus thringiensis strain 108 was isolated from soil and had nematicidal activity against second stage juvenile of plant root-knot nematode, Meloidogyne incognita. The strain 108, a rod shape, spore forming and Gram positive bacterium, produced lecithinase, catalase, and ${\delta}$-endotoxin. The strain 108 belongs to H serotype 3, Bacillus thuringiensis var. kurstaki. A nematicidal substance of the strain 108 was partially purified on Sephadex G-25 gel filtration, activated carbon adsorption, silica gel adsorption, and Sephadex G-10 gel filtration. $LC_{90}$ of the partially purified substance against M incognita was $1.2\;{\mu}g/ml$. The nematicidal substance was stable by heat treatment at $100^{\circ}C$ for 1hr, but was perfectly lost nematicidal activity after autoclave ($110^{\circ}C$, 30 min).

• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.566-570
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• 1997

During sporulation, Bacillus thuringiensis strains produce crystals consist of toxin proteins highly specific against insect pests. Their host specificities are desirable from a standpoint of environmental safety, but also limit market potential. Thus, development of improved Bacillus thuringiensis strains having broad host spectrum will contribute to increase its use. For the construction of Bacillus thuringiensis strain having broad host spectrum, we cloned cry1C gene encoding a toxin protein highly toxic against Spodoptera exigua from a B. thuringiensis isolate and constructed two recombinant plasmids, pUBClC and plC60. The plasmid PUBC1C has a replication origin of the natural plasmid pBC16 from B. cereus which is closely related species to B. thuringiensis, and the pBC16 was known to be replicated by rolling-circle mechanism. The plasmid pIC60 has a replication origin of a resident 60 MDa plasmid from B. thuringiensis subsp. kurstaki HD263, and it is believed that the pIC60 is replicated in a theta mode. The two plasmids were introduced into B. thuringiensis subsp. kurstaki cryB strain, and the transformed strains produced well-shaped bipyramidal crystals. We confirmed the expression of the cry1C gene by SDS-PAGE, and Western blotting. By investigating the segregational stability, it was found that the plasmid pIC60 is more stable than the pUBC1C.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.415-416
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• 2004

Crystals of six new Bacillus thuringiensis serovarieties [coreanensis (H25), konkukian (H34), leesis (H33), seoulensis (H35), sooncheon (H41), and yosoo (HI8a18c)] with different H-antigens, which are toxic to Bombyx mori and/or mosquito larvae, were serologically quite distinct from each other.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.872-879
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• 2015

Many strains of Bacillus cereus cause gastrointestinal diseases, and the closely related insect pathogen Bacillus thuringiensis has also been involved in outbreaks of diarrhea. The diarrheal diseases are attributed to enterotoxins. Sixteen reference strains of B. cereus and nine commercial and 12 reference strains of B. thuringiensis were screened by PCR for the presence of 10 enterotoxigenic genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK, bceT, entFM, and entS), one emetogenic gene (ces), seven hemolytic genes (hlyA, hlyII, hlyIII, plcA, cerA, cerB, and cerO), and a pleiotropic transcriptional activator gene (plcR). These genes encode various enterotoxins and other virulence factors thought to play a role in infections of mammals. Amplicons were successfully generated from the strains of B. cereus and B. thuringiensis for each of these sequences, except the ces gene. Intriguingly, the majority of these B. cereus enterotoxin genes and other virulence factor genes appeared to be widespread among B. thuringiensis strains as well as B. cereus strains.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.152-161
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• 2015

CodY is a highly conserved protein in low G+C gram-positive bacteria that regulates genes involved in sporulation and stationary-phase adaptation. Bacillus thuringiensis is a grampositive bacterium that forms spores and parasporal crystals during the stationary phase. To our knowledge, the regulatory mechanism of CodY in B. thuringiensis is unknown. To study the function of CodY protein in B. thuringiensis, BMB171codY^- was constructed in a BMB171 strain. A shuttle vector containing the ORF of cry1Ac10 was transformed into BMB171 and BMB171codY^-, named BMB171cry1Ac and BMB171codY^-cry1Ac, respectively. Some morphological and physiological changes of codY mutant BMB171codY^-cry1Ac were observed. A comparative proteomic analysis was conducted for both BMB171codY^-cry1Ac and BMB171cry1Ac through two-dimensional gel electrophoresis and MALDI-TOF-MS/MS analysis. The results showed that the proteins regulated by CodY are involved in microbial metabolism, including branched-chain amino acid metabolism, carbohydrate metabolism, fatty acid metabolism, and energy metabolism. Furthermore, we found CodY to be involved in sporulation, biosynthesis of poly-β-hydroxybutyrate, growth, genetic competence, and translation. According to the analysis of differentially expressed proteins, and physiological characterization of the codY mutant, we performed bacterial one-hybrid and electrophoretic mobility shift assay experiments and confirmed the direct regulation of genes by CodY, specifically those involved in metabolism of branched-chain amino acids, ribosomal recycling factor FRR, and the late competence protein ComER. Our data establish the foundation for in-depth study of the regulation of CodY in B. thuringiensis, and also offer a potential biocatalyst for functions of CodY in other bacteria.

• Journal of Life Science
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• v.25 no.2
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• pp.237-242
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• 2015

The use of calcite-forming bacteria (CFB) in crack remediation and durability improvements in construction materials creates a permanent and environmentally-friendly material. Therefore, research into this type of application is stimulating interdisciplinary studies between microbiology and architectural engineering. However, the mechanisms giving rise to these materials are dependent on calcite precipitation by the metabolism of the CFB, which raises concerns about possible hazards to cement-based construction due to microbial metabolic acid production. The aim of this study was to determine target microorganisms that possibly can have bio-corrosive effects on cement mortar and to assess multi-functional CFBs for their safe application to cement structures. The chalky test was first used to evaluate the $CaCO_3$ solubilization feature of construction sites by fungi, yeast, bacterial strains. Not all bacterial strains are able to solubilize $CaCO_3$, but C. sphaerospermum KNUC253 or P. prolifica KNUC263 showed $CaCO_3$ solubilization activity. Therefore, these two strains were identified as target microorganisms that require control in cement structures. The registered patented strains Bacillus aryabhatti KNUC205, Arthrobacter nicotianae KNUC2100, B. thuringiensis KNUC2103 and Stenotrophomonas maltophilia KNUC2106, reported as multifunctional CFB (fungal growth inhibition, crack remediation, and water permeability reduction of cement surfaces) and isolated from Dokdo or construction site were unable to solubilize $CaCO_3$. Notably, B. aryabhatti KNUC205 and A. nicotianae KNUC2100 could not hydrolyze cellulose or protein, which can be the major constituent macromolecules of internal materials for buildings. These results show that several reported multi-functional CFB can be applied to cement structures or diverse building environments without corrosive or bio-deteriorative risks.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.797-808
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• 2016

The experiment of grape leafroller (Herpetogramma luctuosalis) was carried out at Okcheon area from 2007 to 2009 and 2015. The grape leafroller had been occurred at a campbell early' organic vineyard in Okcheon. It's larva was rolling the leaf of grape and ate the leaf. So the leaf of grape decreased. In organic vineyards, adult grape leafroller' generation rate per year showed the first peak in mid-June, the second peak in early -August and the third in mid-September. The larva showed the first peak in early July and the second peak in late August-early September. The grape leaf roller had three generations per year. And it took $60.9{\pm}1.09days$ from egg to adult in growth chamber (VS-91G09M-1300) which the relative humidity conditions was $60{\pm}10%$, temperature $25{\pm}2^{\circ}C$ and photoperiod 16L:8D (The egg : $12{\pm}0days$, larvae : $22.2{\pm}0.22days$, pupa : $10.6{\pm}0.75days$ and adult : $16.1{\pm}0.45days$). It was conducted to find out the effect of microbial pesticide treatments to control H. luctuosalis. The 4 microbial pesticides (Bacillus thurigiensis) were treated twice on the grape leaves in June 11 and 21 at an organic vineyard in Okcheon. On 10 days after last treatment, the control value of all microbial pesticides were more than 95%. When the dates of spraying to the grape leaves were on May 22, June 12 and July 2 each, the effects of microbial pesticide were 73.9%, 93.5% and 43.6% respectively. As a result, it was effective that Bt was sprayed to grape leaves on mid and late June for controling the H. luctuosalis in organic vineyard. And microbial pesticide Bt was thought to be useful to control the grape leafroller in organic vineyard.