• The Plant Pathology Journal
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• v.34 no.4
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• pp.286-296
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• 2018

Maintenance of a beneficial microbial community, especially in the rhizosphere, is indispensable for plant growth and agricultural sustainability. In this sense, plant growth-promoting rhizobacteria (PGPR) have been extensively studied for their role in plant growth promotion and disease resistance. However, the impact of introducing PGPR strains into rhizosphere microbial communities is still underexplored. We previously found that the Proteus vulgaris JBLS202 strain (JBLS202) promoted growth of Kimchi cabbage and altered the relative abundance of total bacteria and Pseudomonas spp. in the treated rhizosphere. To extend these findings, we used pyrosequencing to analyze the changes in bacterial communities in the rhizosphere of Kimchi cabbage after introduction of JBLS202. The alterations were also evaluated by taxon-specific realtime PCR (qPCR). The pyrosequencing data revealed an increase in total bacteria abundance, including specific groups such as Proteobacteria, Acidobacteria, and Actinobacteria, in the treated rhizosphere. Time-course qPCR analysis confirmed the increase in the abundance of Acidobacteria, Actinobacteria, Alphaproteobacteria, and Betaproteobacteria. Furthermore, genes involved in nitrogen cycling were upregulated by JBLS202 treatment indicating changes in ecological function of the rhizosphere soil. Overall, these results indicate that introduction of JBLS202 alters both the composition and function of the rhizosphere bacterial community, which can have direct and indirect effects on plant growth. Therefore, we propose that long-term changes in bacterial composition and community-level function need to be considered for practical use of PGPRs.

• Korean Journal of Environmental Agriculture
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• v.20 no.1
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• pp.63-66
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• 2001

To investgate growth effect of tomato by Bacillus sp. WRD-1 isolated from soil, the Bacillus sp. WRD-1 cultures were treated into tomato cultivated soil with different dilutions (1:100, 1:300, and 1:500) and autoclaved Bacillus cultures as control. Growth and yeild of tomato enhanced in treatments of the Bacillus cultures compared to control. The populations of native bacteria and actinomyces were increased twice in field treated with Bacillus sp. WRD-1 cultures, but the number of mold was decreased. Since the Bacillus sp. WRD-1 promoted growth of tomato and affected population dynamics of microorganism in field, this strain is prominent candidate as a microbial biocide to improve soil potential.

• Journal of Species Research
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• v.9 no.4
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• pp.362-374
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• 2020

A total of 35 bacterial strains were isolated from various sediment samples. From 16S rRNA gene sequence similarities higher than 98.7% and the formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent and predefined bacterial species. No previous official reports have described these 35 species in Korea. The unrecorded species were assigned to 6 phyla, 10 classes, 18 orders, 23 families, and 31 genera. At the genus level, the unrecorded species were affiliated with Terriglobus of the phylum Acidobacteria, as well as with Mycobacterium, Rhodococcus, Kineococcus, Phycicoccus, Agromyces, Cryobacterium, Microbacterium, and Arthrobacter; Catellatospora of the class Actinomycetia; Lacibacter of the class Chitinophagia; Algoriphagus and Flectobacillus of the class Cytophagia; Flavobacterium and Maribacter of the class Flavobacteriia; Bacillus, Cohnella, Fontibacillus, Paenibacillus, Lysynibacillus, and Paenisporosarcina of the class Bacilli; Bradyrhizobium, Gemmobacter, Loktanella, and Altererythrobacter of the class Alphaproteobacteria; Acidovorax of the class Betaproteobacteria; Aliiglaciecola, Cellvibrio, Arenimonas, and Lysobacter of class Gammaproteobacteria; and Roseimicrobium of the class Verrucomicrobia. The selected strains were subjected to further taxonomic characterization, including Gram reaction, cellular and colonial morphology, and biochemical properties. This paper provides detailed descriptions of the 35 previously unrecorded bacterial species.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.375-381
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• 1994

A bacterial strain No. KY-126, which produced extracellular cyclodextrin glycosyltransferase(CGTase), was isolated from soil and identified as Bacillus stearothermophilus KY-126. The enzyme was purified by the treatments of ammonium sulfate precipitation, DEAF-Sephadex, Sephadex G-100 column chromatography. The optimal pH and temperature for the enzyme activity were pH 5.5 and $65^{\circ}C$, respectively. And the enzyme was stable at pH values from 6.0 to 11.0 at $55^{\circ}C$ for 30 min and stable up to $60^{\circ}C$ for 30 min.. The enzyme was inhibited by $HgCl_{2}$. The molecular weight of the enzyme was estimated to be 67,000 by using SDS-PAGE. The maximum conversion from starch to cyclodextrin (CD) by CGTase was 43% and obtained at 6 hr reaction and the ratio of ${\alpha}-,\;{\beta}-,\;{\gamma}-$, CD production at this time was 2.9 : 2.1 : 1.0.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.59-69
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• 2014

One of the major challenges in metabolic engineering for enhanced synthesis of value-added chemicals is to design and develop new strains that can be translated into well-controlled fermentation processes using bioreactors. The aim of this study was to assess the influence of various fed-batch strategies in the performance of metabolically engineered Pseudomonas putida strains, ${\Delta}gcd$ and ${\Delta}gcd-pgl$, for improving production of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using glucose as the only carbon source. First we developed a fed-batch process that comprised an initial phase of biomass accumulation based on an exponential feeding carbon-limited strategy. For the mcl-PHA accumulation stage, three induction techniques were tested under nitrogen limitation. The substrate-pulse feeding was more efficient than the constant-feeding approach to promote the accumulation of the desirable product. Nonetheless, the most efficient approach for maximum PHA synthesis was the application of a dissolved-oxygen-stat feeding strategy (DO-stat), where P. putida ${\Delta}gcd$ mutant strain showed a final PHA content and specific PHA productivity of 67% and $0.83g{\cdot}l^{-1}{\cdot}h^{-1}$, respectively. To our knowledge, this mcl-PHA titer is the highest value that has been ever reported using glucose as the sole carbon and energy source. Our results also highlighted the effect of different fed-batch strategies upon the extent of realization of the intended metabolic modification of the mutant strains.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.255-261
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• 2016

Objectives: This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin. Materials and Methods: Box-formed cavities were prepared on buccal and lingual root surfaces of sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dyeing technique and restored with RMGI (FujiII LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and compared among the groups using ANOVA and Tukey test (p < 0.05). Results: There was a pattern of demineralization in all models, as visualized with scanning electron microscopy. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI. Conclusions: Both microbial and chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, the artificial lesions had a relatively larger extent of demineralization than did the natural lesions. RMGI was incorporated into the superficial layer of the caries-affected dentin.

• Journal of Ginseng Research
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• v.38 no.3
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• pp.215-219
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• 2014

Background: Biological control of plant pathogens using benign or beneficial microorganisms as antagonistic agents is currently considered to be an important component of integrated pest management in agricultural crops. In this study, we evaluated the potential of Bacillus subtilis strain HK-CSM-1 as a biological control agent against Colletotrichum panacicola. Methods: The potential of B. subtilis HK-CSM-1 as a biological control agent for ginseng anthracnose was assessed. C. panacicola was inoculated to ginseng plants and the incidence and severity of disease was assessed to examine the efficacy of the bacterium as a biological control against C. panacicola. Results: Inoculation of Panax ginseng plants with B. subtilis significantly suppressed the number of disease lesions of C. panacicola and was as effective as the chemical fungicide iminoctadine tris(albesilate). The antifungal activity of B. subtilis against C. panacicola was observed on a co-culture medium. Interestingly, treatment with B. subtilis did not significantly affect the diameter of the lesions, suggesting that the mechanism of protection was through the reduction in the incidence of infection related to the initial events of the infection cycle, including penetration and infection via spore germination and appressorium formation rather than by the inhibition of invasive growth after infection. Conclusion: Our results suggest that B. subtilis HK-CSM-1 can be used as an effective and ecologically friendly biological control agent for anthracnose in P. ginseng.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.1098-1102
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• 2005

Properties of rice flours prepared from milled and broken rice produced by pre-washing and subsequent drying process were investigated. Compared to untreated ordinary milled rice, pre-washing process slightly increased lightness of rice flour, while decreased yellowness. Both WAI and WSI were higher in the flour from pre-washed rice, and gel consistency was the highest in the flour from pre-washed broken rice. Pre-washed rice showed increased amylograph peak viscosity and reduced setback values. On the other hand, pre-washed broken rice showed decreased peak viscosity and increased setback values. Differential scanning calorimetry (DSC) results showed that the pre-washing process reduced gelatinization onset- and peak temperatures, with increased gelatinization enthalpy. Total bacteria and yeast count were lower in the pre­washed rice, suggesting the pre-washing process could partially eliminate microbial contamination of ordinary milled rice.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.801-806
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• 2009

A species producing transglutaminase (EC 2.3.2.13) was isolated from forest soil and identified as Streptomyces platensis YK-2. The transglutaminase was purified from culture broth by 50% methanol precipitation, followed by successive chromatography on DEAE-Sephadex. The yield and purification-fold was 63.4% and 2.2-fold, respectively. The purified microbial transglutaminase (MTG) migrated as a single band of approximately 45 kDa upon sodium dodecyl sulfate polyacrylamide gel eletrophoresis. The isoelectric point determined by multichambered electrofocusing was pH $6.0{\sim}7.0$. The enzyme was strongly inhibited by $Hg^{++}$, but was activated by $Cd^{++}$, $Mg^{++}$, $Mn^{++}$, $Pb^{++}$ and reducing agents such as dithiothreitol and mercaptoethanol.

• Korean Journal of Microbiology
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• v.53 no.2
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• pp.71-78
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• 2017

Raman microspectroscopy is a promising tool for microbial analysis at single cell level since it can rapidly measure the cell materials including lipids, nucleic acids, and proteins by measuring the inelastic scattering of a molecule irradiated by monochromatic lights. Using Raman spectra provides high specificity and sensitivity in classification of bacteria at the strain level. In addition, a Raman approach coupled with stabled isotope such as $^{13}C$ and $^2H$ is able to detect and quantify general metabolic activity at single cell level. After bacterial detection process by Raman microspectroscopy, interested unculturable cell sorting and single cell genomics can be accomplished by combination with optical tweezer and microfluidic devices. In this review, the characteristics and applications of Raman microspectroscopy were reviewed and summarized in order to provide a better understanding of microbial analysis using Raman spectroscopy.