• Korean journal of applied entomology
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• 제22권3호
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• pp.186-192
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• 1983

The growth of germ tube of Fusarium oxysporum f. sp. cucumerinum was remarkably inhibited on the water agar treated with 100ppm of Fe-EDDHA, a synthetic iron chelating agent, whereas germination rate of microconidia did not show much differences compare with that of non treated water agar. Both of the germination and the germ tube elongation of microconidia were suppressed significantly in King's B agar by the bacterial siderophores produced by Pseudomonas putida. The highest germination of the chlamydospores was obtained in the soil added with $0.25\%$ of glucose plus $0.05\%$ of asparagine. The chlamydospores of cucumber wil fungus germinated about $14\%$ in rhizosphere soil of 2 day-old cucumber seedlings within 48 hours, and the germination was enhanced notably in rhizosphere soil of 10 day-old seedling. But the rates of germination was not increased according to cucumber growth age after 10 day-old seedling. The effect of P. putida and Fe-EDDHA on the germination on chlamydospores in conducive soil was not pronounced in the non-rhizosphere soil added with nutrient. However, the germination was suppressed significantly both in rhizosphere soil and in rhizosphere soil added with nutrient. The suppression of chlamydospore germination was greater in the bacteria inoculated soil than that in Fe-EDDHA treated soil.

• Korean Journal of Microbiology
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• 제46권1호
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• pp.63-67
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• 2010

Proteases catalyze hydrolytic cleavage of a peptide bond between amino acids and occupy pivotal positions in application in physiological and commercial fields. During the screening for novel bacteria producing extracellular protease, two bacterial strains, WD12 and WD32, were isolated from rotten trees and they made clear zone on LB plates supplemented with 1% skim milk. The similarities of 16S rRNA gene sequence of either WD12 or WD32 to GenBank database showed the highest to Pseuoxanthomonas mexicana as 97.8 and 99.8%, respectively. Phylogenetic analysis showed that both isolated was located within the cluster comprising P. mexicana and P. japonesis. WD12 and WD32 were catalase- and oxidase-positive, Gram-negative rod strains. In case of WD12, it could assimilate malate, but could not assimilate D-mannose, which were different characteristics from P. mexicana. Both Pseuoxanthomonas sp. WD12 and WD32 optimally produced extracellular protease at $35-37^{\circ}C$, and maximal activity showed as 656 unit/ml and 267 unit/ml, respectively.

• The Korean Journal of Pesticide Science
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• 제10권2호
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• pp.138-148
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• 2006

Two bacteria were isolated from the continuously pesticide-used soil under plastic film house and upland condition. The degradation test of several pesticides by the selected bacteria, B59 and B71, were conducted. The degradation rates for 6 pesticides, procymidone, chlorothalonil, ethoprophos parathior, alachlor and pendimethalin, in medium by the isolates were 21.1% to 53.2% higher than non-inoculated medium. Under shaking culture condition, 90% to 95% of procymidone was degraded after 21 days treatment. Parathion was degraded in the range of 60% to 100% by B71 and B59, respectively. Otherwise 70% of alachlor was degraded by the two isolated bacteria during same period. The pH was not significantly affected for degradation of pesticides. The bacterial strains, B59 and B71 was identified as Acinetobacter sp. and as Pseudomonas sp. based on morphological, biochemical and physiological characteristics, and identity and similarity of automatic identification system, Biolog and MIDI.

• Journal of the Korea Organic Resources Recycling Association
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• 제12권4호
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• pp.139-147
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• 2004

We have isolated two bacterial strains, FM-02 and AL-02, which produced EPS from forest soil for the restoration of forest fire by promoting soil aggregation. FM-02 was found to be Gram negative rod and belong to Beta Proteobacterium sp. through 16s-rDNA sequence analysis, and AL-02 was Gram positive rod and showed 81% of similarity to Zoogloea sp. through the analysis of 16s-rDNA sequence. FM-02 and AL-02 produced about 1.8g and 8.3g of EPS, respectively, per 1L of culture as dry weight. Flocculation activity (FA) was also measured in two strains. FM-02 showed 2.31 FA against active carbon, and AL-02 showed 6.21 FA against kaolin clay. From these results, we expect that AL-02 strain will be applied as a good biological material for the reduction of forest soil erosion by wild and rain after fire through promoting coagulation of soil particles.

• Journal of Life Science
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• 제30권6호
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• pp.491-500
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• 2020

Lactic acid bacteria are widely known to prevent and treat intestinal health conditions, heart disease, depression, and obesity. In Korea, such bacteria are commonly consumed through various fermented foods, although most are isolated from kimchi, and research on the lactic acid bacteria in fermented seafood is insufficient. This study was therefore conducted to observe changes in bacterial flora according to the culture date of lactic acid bacteria in the fermentation of traditional Korean Gajami Sikhae produced in Pohang and to isolate the bacteria of probiotic value. The bacteria were periodically isolated and identified from date of preparation to 50 days after preparation to investigate which Lactobacillus are involved in Gajami Sikhae. As fermentation progressed, it was confirmed that Pediococcus sp. and Lactobacillus sp. participate predominantly in the early and later periods of fermentation, respectively. During the entire fermentation period, 170 isolates were screened, and the following five species were found to be involved: Pediococcus pentosaceus, Pediococcus inopinatus, Leuconostoc mesenteroides, Lactobacillus brevis, and Lactobacillus plantarum. Five strains of these species were selected through acid and bile tolerance tests, and their coaggregation, autoaggregation, hydrophobicity, antibacterial, and antioxidant activities were then evaluated. As a result, it is thought that L. brevis GS1022, which has excellent digestive fluid resistance, and P. inopinatus GS316, which has excellent cohesiveness, may be useful as probiotic strains.

• Research in Plant Disease
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• 제24권3호
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• pp.221-232
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• 2018

Rhizobacteria play important roles in plant growth and health enhancement and render them resistant to not only biotic stresses but also abiotic stresses, such as low/high temperature, drought, and salinity. This study aimed to select plant growth promoting rhizobacteria (PGPR) with the capability to mitigate biotic and abiotic stress effects on tomato plants. We isolated a novel PGPR strain, Variovorax sp. PMC12 from tomato rhizosphere. An in vitro assay indicated that strain PMC12 produced ammonia, indole-3-acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, which are well-known traits of PGPR. The aboveground fresh weight was significantly higher in tomato plants treated with strain PMC12 than in non-treated tomato plants under various abiotic stress conditions including salinity, low temperature, and drought. Furthermore, strain PMC12 also enhanced the resistance to bacterial wilt disease caused by Ralstonia solanacearum. Taken together, these results indicated that strain PMC12 is a promising biocontrol agent and a biostimulant to reduce the susceptibility of plants to both abiotic and biotic stresses.

• Korean Journal of Food Science and Technology
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• 제34권4호
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• pp.666-672
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• 2002

Changes in chemical characteristic, microflora, and sensory evaluation of fish sauce extracted at an interval of one week from fermented solution were investigated. pH was reduced from 6.0 to 4.5, and trimethylamine oxide from 132.5 to 87.2 mg/100g during fermenting periods. Trimethylamine increased from 5.6 to 50.2 mg/100g, and volatile basic nitrogen from 48.3 to 232.5 mg/100g. Bacterial flora isolated from the fish sauce were 70% Lactobacillus sp. and 13% Bacillus sp. Among the free amino acids, alanine, glutamic acid, valine, and methionine contents constitute 40% of the total free amino acids. Major non-volatile organic acid of the fish sauce was lactic acid (76%). Sensory evaluation results of the fish sauce were higher than the traditional soybean sauce after 28 days of fermentation.

• Research in Plant Disease
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• 제27권4호
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• pp.129-136
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• 2021

Rice is responsible for the stable crop of 3 billion people worldwide, about half of Asian depends on it, and rice is grown in more than 100 countries. Rice diseases can lead to devastating economic loss by decreasing yield production, disturbing a stable food supply and demand chain. The most commonly used method to control rice disease is chemical control. However, misuse of chemical control can cause environmental pollution, residual toxicity, and the emergence of chemical-resistant pathogens, the deterioration of soil quality, and the destruction of biodiversity. In order to control rice diseases, research on alternative biocontrol is actively pursued including microorganism-oriented biocontrol agents. Microbial agents control plant disease through competition with and antibiotic effects and parasitism against plant pathogens. Microorganisms isolated from the rice rhizosphere are studied comprehensively as biocontrol agents against rice pathogens. Bacillus sp., Pseudomonas sp., and Trichoderma sp. were reported to control rice diseases, such as blast, sheath blight, bacterial leaf blight, brown spot, and bakanae diseases. Here we reviewed the microorganisms that are studied as biocontrol agents against rice diseases.

• Microbiology and Biotechnology Letters
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• 제36권1호
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• pp.28-33
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• 2008

The expression vector (pWHM3-TR1R2) for sprT gene encoding Streptomyces griseus trypsin (SGT) followed by two regulatory genes, sgtR1 and sgtR2, was introduced into Streptomyces lividans TK24 and Streptomyces griseus IFO 13350. Various media with different compositions were used to maximize the productivity of SGT in the recombinant trains. he SGT productivity was best when the transformant of S. lividans TK24 was cultivated in R2YE medium (0.74 unit/mL) at 5 days of cultivation. C5/L (0.66 unit/mL) medium also gave a good productivity, but Livid (0.08 unit/mL) and NDSK (0.06 unit/mL) yielded poor productivities. S. griseus IFO 13350/pWHM3-TR1R2 produced SGT by 1.518 unit/mL (C5/L), 1.284unit/mL (R2YE),0.932 unit/mL (NDSK), and 0.295 unit/mL (Livid) at 7 days of cultivation, which was much higher than those from S. lividans TK24/TR1R2. The SGT protein was purified from the culture broth of S. griseus IFO 13350/pWHM3-TR1R2 in C5/L to homogeneity via ammonium sulfate fractionation, and CM-sepharose and SP-sepharose column chromatographies. The specific activity of purified SGT was 69,252 unit/mg, and the final purification fold and recovery yield were 6.5 and 1.4%, respectively.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1138-1149
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• 2017

The use of microalgal biomass is an interesting technology for the removal of heavy metals from aqueous solutions owing to its high metal-binding capacity, but the interactions with bacteria as a strategy for the removal of toxic metals have been poorly studied. The goal of the current research was to investigate the potential of Burkholderia tropica co-immobilized with Chlorella sp. in polyurethane discs for the biosorption of Hg(II) from aqueous solutions and to evaluate the influence of different Hg(II) concentrations (0.041, 1.0, and 10 mg/l) and their exposure to different contact times corresponding to intervals of 1, 2, 4, 8, 16, and 32 h. As expected, microalgal bacterial biomass adhered and grew to form a biofilm on the support. The biosorption data followed pseudo-second-order kinetics, and the adsorption equilibrium was well described by either Langmuir or Freundlich adsorption isotherm, reaching equilibrium from 1 h. In both bacterial and microalgal immobilization systems in the co-immobilization of Chlorella sp. and B. tropica to different concentrations of Hg(II), the kinetics of biosorption of Hg(II) was significantly higher before 60 min of contact time. The highest percentage of biosorption of Hg(II) achieved in the co-immobilization system was 95% at pH 6.4, at 3.6 g of biosorbent, $30{\pm}1^{\circ}C$, and a mercury concentration of 1 mg/l before 60 min of contact time. This study showed that co-immobilization with B. tropica has synergistic effects on biosorption of Hg(II) ions and merits consideration in the design of future strategies for the removal of toxic metals.