• The Plant Pathology Journal
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• 제23권2호
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• pp.103-105
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• 2007

Mechanical transmission of barley seedlings with barley yellow mosaic virus (BaYMV) is generally inefficient and is the major constraint for testing cultivar resistance to the virus. To explore mechanical transmission, BaYMV-infected barley plants were grown at different conditions and used as inoculum sources to seedlings of susceptible barley cultivar Baegdong. Extracts prepared from BaYMV-infected Baegdong plants at 47, 53, 74, and 90 days after symptom appearance (DASA) and grown at 10 and $12^{\circ}C$ gave 10, 30, 68 and 76% infection, respectively on inoculated susceptible barley cv. Baegdong seedlings. While Jinyangbori, another susceptible cultivar obtained 95% infection rate inoculated with extracts from 90 DASA disease source and grown at $10/12^{\circ}C$. However, low infection rates were obtained when the virus sources were grown in a greenhouse at $15-18^{\circ}C$. Our results indicate that longer incubation period and lower temperature are required for virus accumulation and stability.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권2호
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• pp.107-111
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• 2001

The addition of a limited concentration of yeast extract to a minimal salt medium (MSM) enhanced cell growth and increased the production of curdlan whereas nitrogen-limitation was found to be essential for the higher production of curdlan by Agrobacterium sp. ATCC 31749. As the amount of the inoculum increased, the cell growth as well as the production of curdlan also increased in the MSM without a nitrogen source. The cell growth and production of curdlan increased as the initial pH of the medium decreased as low as 5.0. The conversion rate and concentration of curdlan from 2% (w/v) glucose in the MSM with concentrated cells under nitrogen deletion was 67% and 13.4 g/L, respectively. The highest conversion rate of curdlan under the conditions optimized in this study was 71% when the glucose concentrations was 1% (w/v).

• 식물병연구
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• 제17권1호
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• pp.82-85
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• 2011

2009년 전남 해남 지역의 논에서 벼 키다리병과 유사한 병징을 나타내는 피를 채집하여 병원균을 분리하였다. 이병 식물체는 줄기가 고사하여 하얗게 말라 죽고, 줄기 표면에 흰가루 모양의 포자가 형성되었다. 분리균은 균학적 특성과 분자생물학적 특성에 따라 Fusarium fujikuroi로 동정되었다. Translation elongation factor 1-alpha 유전자의 염기서열 분석 결과, GenBank에 등록된 F. fujikuroi와 상동성을 나타내었다. 벼와 피를 대상으로 침지접종에 의해 병원성을 확인하였으며, 이는 피가 벼 키다리병의 전염원으로서의 역할을 할 수 있음을 의미한다. 따라서 벼 키다리병의 방제와 건전종자의 채종을 위해서는 논에 발생한 이병식물체뿐 아니라 전염원으로 작용할 수 있는 피를 제거해야 할 것으로 생각된다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권1호
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• pp.45-49
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• 1996

A series of in vitro experiments was conducted to investigate response of rumen bacterial deamination to the ionophore salinomycin. Addition of salinomycin to the inoculum, strained rumen fluid, depressed ammonia production from casein, while increased accumulation of ${\alpha}$-amino acids. This suggests an inhibitory effect of salinomycin on ruminal deamination. When the effect in washed bacterial suspension was monitored with individual amino acid, aspartic acid degradation was markedly inhibited by salinomycin. This inhibition was not observed when the mixed rumen bacteria were ultrasonically disrupted and used as the enzyme source. Extent of the inhibition tended to be higher in the bacteria source from sheep on a high roughage diet. From these results it was speculated that the inhibition of deamination with salinomycin is caused by a decreased transport of amino acid into the bacterial cells as well as a decreased proportion of deaminating bacteria in the rumen.

• 한국균학회지
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• 제30권1호
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• pp.61-65
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• 2002

한국 전통주인 막걸리의 원료인 누룩에 대한 연구의 일환으로 각종 누룩 균주를 단독 접종하여 술담그기를 한 후 맛과 알코올 농도등을 기존의 방법으로 생산된 막걸리와 비교 연구하였다. 무작위로 선정된 4가지의 균의 성장과정을 무균 상태에서 다양한 수분 첨가조건으로 조사하였으며, 전분 분해능도 관찰하였다. 균사의 성장과정에서 이산화탄소 생산과 무게 손실을 측정하였으며, 그 결과는 균종에 따라서 다르게 나타났다. Abisida와 Rhizopus 균에서는 수분 함량이 적은 곳에서 잘 자라는 반면 Aspergillus와 Mucor는 비교적 수분함량이 많은 곳에서 잘 자랐다. 수분 첨가량이 적을수록 전통 누룩에서 발견된 균들이 잘 자랐다. 본 연구에서는 고두밥을 이용해 술을 담그는 전통적인 방법에 의한 경우와 단독 누룩 균을 이용하여 술담그기를 한 경우 그 술의 성분과 맛을 서로 비교하였다. 그 결과, 우리의 전통주는 접합균을 이용한 많은 누룩으로 만들어지고, 대표적인 균들은 Absidia, Mucor 및 Rhizopus로 생각되었고, 전통 누룩은 효소원이라기 보다는 균종원으로 추론되었다.

• 대한환경공학회지
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• 제38권12호
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• pp.635-640
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• 2016

미생물연료전지(MFC)는 하 폐수내의 유기물로부터 전기를 생산할 수 있는 획기적인 기술이지만, 실용화를 위해서는 하 폐수 내의 질소를 제거할 수 있어야 한다. 본 연구에서는 두 개의 대면적 SEA (separator electrode assembly)로 구성된 평판형 외기환원전극 미생물연료전지(FA-MFC)를 이용하여 질산화 전배양의 유무와 식종원에 따른 총질소제거율을 평가하였다. 질산화 전배양 단계에서 FA-MFC의 질산화율은 식종원과는 무관하게 99% 이상을 나타냈다. 질산화 및 탈질 단계에서 300 mg-COD/L 이하의 낮은 유기물 농도에서는 전배양을 하지 않은 조건의 총질소제거율이 가장 높았다. 유기물 농도가 증가할수록 더 높은 총질소제거율을 나타냈으며, 유기물제거율은 모든 조건에서 95% 이상을 나타냈지만, 종속영양탈질에만 이용되지는 않은 것으로 판단된다. FA-MFC의 전기 발생량은 매우 낮았지만, 유기물과 질소를 동시에 제거할 수 있다는 장점이 있기 때문에 획기적인 하 폐수처리공법으로 발전시킬 수 있으리라 기대된다.

• The Plant Pathology Journal
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• 제38권2호
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• pp.90-101
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• 2022

Pathogenicity of eight Bacillus strains to seedlings of four cotton cultivars was evaluated under greenhouse conditions. Each of the tested cultivars was individually treated with powdered inoculum of each bacterial strain. Untreated seeds were planted as control treatments in autoclaved soil. Effects of the tested strains on levels and activities of some biochemical components of the infected seedlings were also assayed. The biochemical components included total soluble sugars, total soluble proteins, total free amino acids, peroxidase, polyphenol oxidase, phenols, and lipid peroxidation. ANOVA showed that Bacillus strain (B) was a very highly significant source of variation in damping-off and dry weight. Cotton cultivar (V) was a nonsignificant source of variation in damping-off while it was a significant source of variation in dry weight. B × V interaction was a significant source of variation in damping-off and a nonsignificant source of variation in dry weight. Bacillus strain was the most important source of variation as it accounted for 59.36 and 64.99% of the explained (model) variation in damping-off and dry weight, respectively. The lack of significant correlation between levels and activities of the assayed biochemical components and incidence of damping-off clearly demonstrated that these biochemical components were not involved in the pathogenicity of the tested strains. Therefore, it was hypothesized that the pathogenicity of the tested strains could be due to the effect of cell wall degrading enzymes of pathogenic toxins. Based on the results of the present study, Bacillus strains should be considered in studying the etiology of cotton seedling damping-off.

• Asian-Australasian Journal of Animal Sciences
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• 제31권1호
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• pp.63-70
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• 2018

Objective: The aim of the study was to isolate gossypol-degrading bacteria and to assess its potential for gossypol degradation. Methods: Rumen liquid was collected from fistulated cows grazing the experimental pasture. Approximately 1 mL of the rumen liquid was spread onto basal medium plates containing 2 g/L gossypol as the only source of carbon and was then cultured at $39^{\circ}C$ to isolate gossypol-degrading bacteria. The isolated colonies were cultured for 6 h and then their size and shape observed by microscope and scanning electron microscope. The 16S rRNA gene of isolated colonies was sequenced and aligned using National Center for Biotechnology Information-Basic Local Alignment Search Tool. The various fermentation conditions, initial pH, incubation temperature, inoculum level and fermentationperiod were analyzed in cottonseed meal (CSM). The crude protein (CP), total gossypol (TG), and free gossypol (FG) were determined in CSM after fermentation with isolated strain at $39^{\circ}C$ for 72 h. Results: Screening results showed that a single bacterial isolate, named Rumen Bacillus Subtilis (RBS), could use gossypol as a carbon source. The bacterium was identified by 16S rDNA sequencing as being 98% homologous to the sequence of Bacillus subtilis strain GH38. The optimum fermentation conditions were found to be 72 h, $39^{\circ}C$, pH 6.5, moisture 50%, inoculum level $10^7cell/g$. In the optimum fermentation conditions, the FG and TG content in fermented CSM decreased 78.86% and 49% relative to the control. The content of CP and the essential amino acids of the fermented CSM increased respectively, compared with the control. Conclusion: The isolation of a gossypol-degrading bacterium from the cow rumen is of great importance for gossypol biodegradation and may be a valuable potential source for gossypol-degradation of CSM.

• Journal of Microbiology and Biotechnology
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• 제21권1호
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• pp.37-42
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• 2011

A new versatile acrylonitrile-bioconverting strain isolated from a petroleum-contaminated sludge sample and identified as Rhodococcus ruber AKSH-84 was used for optimization of medium and biotransformation conditions for nitrilase activity to produce acrylic acid. A simple and rapid HPLC protocol was optimized for quantification of acrylic acid, acrylamide, and acrylonitrile. The optimal medium conditions for nitrilase activity were pH of 7.0, temperature of $30^{\circ}C$, agitation of 150 rpm, and inoculum level of 2%. Glycerol as a carbon source and sodium nitrate as the nitrogen source provided good nutritional sources for achieving good biotransformation. Nitrilase activity was constitutive in nature and was in the exponential growth phase after 24 h of incubation under optimal conditions without addition of any inducer. The substrate preference was acrylonitrile and acetonitrile. The present work demonstrates the biotransformation of acrylonitrile to acrylic acid with the new strain, R. ruber AKSH-84, which can be used in green biosynthesis of acrylic acid for biotechnological processes. The nitrilase produced by the isolate was purified and characterized.

• Asian-Australasian Journal of Animal Sciences
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• 제18권7호
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• pp.990-996
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• 2005

The effect of diets varying in level and source of nitrogen (N) and fermentable organic matter on dynamic characteristics of microbial populations in rumen liquor and their impact on substrate fermentation in vitro was studied. The diets tested were straw alone, straw+concentrate mixture and straw+urea molasses mineral block (UMMB) lick. The same diets were taken as substrates and tested on each inoculum collected from the diets. Diet had no effect on the amino acid (AA) composition of either bacteria or protozoa. Differences among the diets in intake, source of N and OM affected bacterial and protozoal characteristics in the rumen. Upper asymptote of gas production (Y$\alpha$) had a higher correlation with bacterial pool size and production rate than with protozoal pool size and production rate. Among the parameters of the gas production model, Y$\alpha$ and lag time in total gas has showed significant (p<0.01) correlation with bacterial characteristics. Though the rate constant of gas production significantly differed (p<0.01) between diet and type of straw, it was least influenced by the microbial characteristics. The regression coefficient of diet and type of straw for Y$\alpha$ indicated that the effect of diet on Y$\alpha$ was threefold higher than that of the straw. As microbial characteristics showed higher correlation with Y$\alpha$, and diet had more influence on the microbial characteristics, gas production on a straw diet could be used effectively to understand the microbial characteristics.