ABSTRACT Aims: Dickeya dadantii is a pathogenic bacterium causing bacterial soft rot disease in plants. The bacterium uses a homoserine lactone signal in its quorum sensing process to express the virulence factor genes. Anti-quorum sensing is a new approach to control plant pathogenic bacteria. The aims of this study are to characterize AHL-lactonase enzyme produced by Bacillus thuringiensis SGT3g and to determine its effectiveness in inhibiting virulence of D. dadantii. Methodology and results: Activity of AHL-lactonase was determined using Chromobacterium violaceum as a bacterial biosensor. The crude extract enzymes of AHL-lactonase on both as extracellular and intracellular enzymes were analyzed their enzyme activity of protein precipitation and dialysis products. The optimum activity of AHL-lactonase was found at 30 °C and pH 5-8. Bacillus thuringiensis SGT3g was capable to reduce soft rot symptom disease caused by D. dadantii on Phalaenopsis orchid leaves after 24 h of incubation. Conclusion, significance and impact study: Bacillus thuringiensis SGT3g was capable to degrade AHL signal of C. violaceum and D. dadantii. The activity AHL-lactonase of B. thuringiensis SGT3g had a wide range of pH and temperature. The lactonase could reduce soft rot symptom disease caused by D. dadantii without any growth inhibition of D. dadantii on orchid leaves. Bacillus thuringiensis SGT3g can be used as an alternative biopesticide to control phytopathogenic bacteria due to its capability to suppress bacterial pathogenic virulence.
Bacillus thuringiensis

Biochemical characteristics of B. subtilis Du, B. subtilis NT, B. subtilis ATCC 6633 were primarily the same, but their size was smaller with small colonies, R form and opaquely white color. 72 hours was culture duration for obtaining highest amount of amylase in B. subtilis ATCC, while in B. subtilis NT and B. subtilis Du – 96 hours
Bacillus ; Bacillus subtilis ; Biochemistry

Aims: To characterize xylanolytic enzyme producing strains of Bacillus subtilis from the intestinal tract of a cabbage looper (Trichoplusia ni (Hübner)) larvae. Methodology and results: Approximately 5 g of intestinal content from the instar larvae were homogenated and serially diluted 10-4 -10-6 times with sterile normal saline before being spread onto duplicate tryptic soy agar plates. Every different colony was selected to test for xylanase production. Of six isolates, only one was found to be positive for xylanase production by screening agar. Biochemical characteristics and 16S rRNA gene sequencing indicated that the Bact-I was closely related to Bacillus subtilis. Optimization of xylanase enzyme production showed that Bacillus subtilis was able to produce xylanase enzymes when grown in a culture medium containing 2% (w/v) corn stover and 0.6% (w/v) yeast extract at pH 10 and 37 °C. The xylanase gene was cloned and characterized. The result revealed that the xylanase gene of Bacillus subtilis was homology to the β-1,4 endo-xylanase gene. Conclusion, significance and impact of study: A xylanase producing Bacillus subtilis was isolated from the intestinal tract of a cabbage looper (Trichoplusia ni (Hübner)) larvae. Optimization and evaluation of the xylanase activity of Bacillus subtilis indicated that it could be useful for xylanase production or as a probiotic for improving animal feed stuff.
Bacillus subtilis

We have now construted a novel recombinant baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) producing polyhedra with Bacillus thuringiensis (Bt) Cry1Ac crystal protein. The recombinant polyhedra produced by the recombinant baculovirus, Btrus, in insect cells was characterized. The recombinant baculovirus has two independent transcription units in opposite orientations with two promoters, p10 or polyhedrin gene promoter each initiating transcription of either native polyhedrin or fusion protein with polyhedrin and Bt Cry1Ac crystal protein. Suprisingly, this recombinant baculovirus stably produced recombinant polyhedra which were nearly similar to those of wild-type AcNPV. The immunogold staining experiment showed that the recombinant polyhedra were assembled with polyhedrin and Bt Cry1Ac crystal protein, and contained virus paticles. Insecticidal toxicity of recombinant polyhedra of Btrus to the fall webworm, Hyphantrea cunea, was strikingly improved in comparison with the wild-type AcNPV.
Bacillus thuringiensis* ; Bacillus* ; Baculoviridae* ; Insects ; Nucleopolyhedrovirus

Aims: A 2,2-dichloropropionic acid (2,2-DCP) naturally degrading bacterial species, strain SN1 was successfully isolated from cow dung capable of utilizing the substance as the sole carbon source and energy. Methodology and results: Strain SN1 was preferred over other strains (SN2, SN3 and SN4) following observations on its rapid growth in 20 mM 2,2-DCP liquid minimal media. Since strain SN1 clearly exhibited tolerance towards 2,2-DCP, its growth in various concentrations (10 mM, 20 mM, 30 mM and 40 mM) of the substance was evaluated. The study found the bacteria grew particularly well in 20 mM 2,2-DCP with the highest chloride release of 39.5 µmole Cl- /mL while exhibiting a remarkably short doubling time of 3.85 h. In view of such notable characteristics, species identification via Biolog GEN III system and 16S rRNA analysis was performed and established strain SN1 as Bacillus cereus. Conclusion, significance and impact of study: Considering the rapid growth of B. cereus strain SN1 in such medium, its employment as a bioremediation agent to treat 2,2-DCP contaminated soils may prove beneficial. Moreover, this is the first reported case of a Bacillus sp. isolated from cow dung capable of utilizing 2,2-DCP. Therefore, further assessment into its ability to degrade other types of haloalkanoic acids merit special consideration.
Bacillus cereus

No abstract available.
Bacillus anthracis* ; Bacillus*

No abstract available.
Bacillus anthracis* ; Bacillus*

No abstract available.
Bacillus anthracis* ; Bacillus* ; Classification*

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles.
Aflatoxins* ; Agar ; Aspergillus flavus* ; Aspergillus* ; Bacillus megaterium* ; Bacillus* ; Germination ; Pseudomonas* ; Sphingomonas

In our previous studies, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15 have been shown to be antagonistic to Aspergillus flavus in stored rice grains. In this study, the biocontrol activities of these strains were evaluated against Aspergillus candidus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum, which are predominant in stored rice grains. In vitro and in vivo antifungal activities of the bacterial strains were evaluated against the fungi on media and rice grains, respectively. The antifungal activities of the volatiles produced by the strains against fungal development and population were also tested using I-plates. In in vitro tests, the strains produced secondary metabolites capable of reducing conidial germination, germ-tube elongation, and mycelial growth of all the tested fungi. In in vivo tests, the strains significantly inhibited the fungal growth in rice grains. Additionally, in I-plate tests, strains KU143 and AS15 produced volatiles that significantly inhibited not only mycelial growth, sporulation, and conidial germination of the fungi on media but also fungal populations on rice grains. GC-MS analysis of the volatiles by strains KU143 and AS15 identified 12 and 17 compounds, respectively. Among these, the antifungal compound, 5-methyl-2-phenyl-1H-indole, was produced by strain KU143 and the antimicrobial compounds, 2-butyl 1-octanal, dimethyl disulfide, 2-isopropyl-5-methyl-1-heptanol, and 4-trifluoroacetoxyhexadecane, were produced by strain AS15. These results suggest that the tested strains producing extracellular metabolites and/or volatiles may have a broad spectrum of antifungal activities against the grain fungi. In particular, B. megaterium KU143 and P. protegens AS15 may be potential biocontrol agents against Aspergillus and Penicillium spp. during rice grain storage.
Aspergillus flavus ; Aspergillus fumigatus ; Aspergillus* ; Bacillus megaterium* ; Bacillus* ; Fungi ; Germination ; In Vitro Techniques ; Penicillium* ; Pseudomonas*