• 한국환경과학회지
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• 제27권9호
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• pp.771-780
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• 2018

To develope a microbial weed control agent, HCN-producing bacteria were isolated, and their characteristics were investigated. A selected strain of WA15 was identified as Pseudomonas koreensis by morphological, cultural, biochemical and 16S rRNA gene analyses. The conditions for HCN production was investigated by a One-Variable-at-a-Time (OVT) method. The optimal HCN production conditions were tryptone 1%, glycine 0.06%, NaCl 1%, and an initial pH and temperature of 5.0 and $30^{\circ}C$, respectively. The major component for HCN production was glycine. Under optimal conditions, HCN production was about 3 times higher than that of the basal medium. The WA15 strain had physiological activities, such as indoleacetic acid that was associated with the elongation of plant roots and siderophore and ammonification inhibiting fungal growth, and produced hydrolytic enzymes, such as cellulase, pectinase and lipase. The strain was able to inhibit the growth of phytopathogenic fungi, such as Rhizoctonia solani, Botrytis cinerea and Fusarium oxysporum, by the synergistic action of volatile HCN and diffusible antimicrobial compounds. A microscopic observation of R. solani that was teated with the WA15 strain showed morphological abnormalities of fungal mycelia, which could explain the role of the antimicrobial metabolites that were produced by the WA15 strain. The volatile HCN produced by the WA15 strain was also found to have insecticidal activity against termites. Our results indicate that Pseudomonas koreensis WA15 can be applied as a microbial agent for weed control and also as a termite repellent. Furthermore, it could be applied as a microbial termiticidal agent to replace synthetic insecticides.

• The Plant Pathology Journal
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• 제29권2호
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• pp.182-192
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• 2013

Numerous root-associated bacteria (rhizobacteria) are known to elicit induced systemic resistance (ISR) in plants. Bacterial cell-density-dependent quorum sensing (QS) is thought to be important for ISR. Here, we investigated the role of QS in the ISR elicited by the rhizobacterium, Serratia marcescens strain 90-166, in tobacco. Since S. marcescens 90-166 produces at least three QS signals, QS-mediated ISR in strain 90-166 has been difficult to understand. Therefore, we investigated the ISR capacity of two transgenic tobacco (Nicotiana tabacum) plants that contained either bacterial acylhomoserine lactone-producing (AHL) or -degrading (AiiA) genes in conjunction with S. marcescens 90-166 to induce resistance against bacterial and viral pathogens. Root application of S. marcescens 90-166 increased ISR to the bacterial pathogens, Pectobacterium carotovorum subsp. carotovorum and Pseudomonas syringae pv. tabaci, in AHL plants and decreased ISR in AiiA plants. In contrast, ISR to Cucumber mosaic virus was reduced in AHL plants treated with S. marcescens 90-166 but enhanced in AiiA plants. Taken together, these data indicate that QS-dependent ISR is elicited by S. marcescens 90-166 in a pathogen-dependent manner. This study provides insight into QS-dependent ISR in tobacco elicited by S. marcescens 90-166.

• 미생물학회지
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• 제43권4호
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• pp.279-284
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• 2007

식물호르몬(phytohormone)을 생성하며 불용성 인산 가용화능이 있는 세균을 근권에서 분리하여 각각의 생성능을 조사하고 토마토 씨앗에 적용하여 생장촉진 가능성을 조사함으로써 분리 균주의 생물학적 비료로서의 가능성을 제시하고자 하였다. 분리 균주인 Bacillus sp. PS2와 RFO41은 첨가된 두 종류의 500 mg/L 불용성 인산을 약 80% 이상 가용화 시켰으며, 펩톤이 풍부한 생장배지에서 여러 가지 식물호르몬을 생성하였다. 이를 토대로 토마토 씨앗의 생장촉진 실험을 수행한 결과, PS2와 RFO41이 적용된 실험군의 발아한 토마토모종의 뿌리와 줄기의 길이 생장은 대조군에 비하여 각각 26.8과 34.8% 및 45.5와 36.5%가 증가하였다. 이 결과는 분리 균주인 Bacillus sp. PS2와 RFO41의 인산 가용화능과 식물호르몬의 생성능이 토마토 씨앗의 발아와 생장에 직접적인 영향을 주는 요인으로 작용한 결과라고 판단할 수 있으며, 생물학적 비료로서의 가치를 뒷받침하는 것이라고 할 수 있다.

• 한국환경과학회지
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• 제19권10호
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• pp.1307-1314
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• 2010

This study was conducted to isolate and characterize a novel feather-degrading bacterium producing keratinase activity. A strain K9 was isolated from soil at poultry farm and identified as Xanthomonas sp. K9 by phenotypic characters and 16S rRNA gene analysis. The cultural conditions for the keratinase production were 0.3% fructose, 0.1% gelatin, 0.04% $K_2HPO_4$, 0.06% $KH_2PO_4$, 0.05% NaCl and 0.01% $FeSO_4$ with an initial pH 8.0 at $30^{\circ}C$ and 200 rpm. In an optimized medium containing 0.1% chicken feather, production yield of keratinase was approximately 8-fold higher than the yield in basal medium. The strain K9 effectively degraded chicken feather meal (67%) and duck feather (54%), whereas human nail and human hair showed relatively low degradation rates (13-22%). Total free amino acid concentration in the cell-free supernatant was about 25.799 mg/l. Feather hydrolysate produced by the strain K9 stimulated growth of red pepper, indicating Xanthomonas sp. K9 could be not only used to increase the nutritional value of chicken feather but also a potential candidate for the development of natural fertilizer applicable to crop plant soil.

• 한국미생물·생명공학회지
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• 제36권4호
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• pp.268-275
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• 2008

경북포항지역의 해안사구지역에서 서식하는 11종의 해안사구 식물의 근권으로부터 1,330균주의 근권세균들을 분리하였다. 이들 분리된 근권세균등 중에서 9종의 주요 식물병원성 진균인 Phytophthora capsici, Fusarium oxysporum, Corynespora casriicola, Colletotrichum acutatum, Botrytis cinerea, Rhizoctonia solani AG-1(IA), Pythium ultimum, Rhizoctonia solani AG-1(IB)에 대하여 넓은 항진균성 스펙트럼을 가지고 동시에 생장촉진호로몬 옥신을 생산하는 23균주의 근권세균을 선발하였다. 1차 선발된 23균주의 옥신 생산성 사구식물근권세균들에서 19균주가 항진균성 siderophore를, 4균주가 항진균성 cellulase를 생산할 수 있었으며, 17균주는 불용성 인산염을 분해할 수 있었다. 또, 23균주의 선발된 사구식물생장 촉진 근권세균들은 16S rDNA 염기서열 조사와 Bergey's manual에 의하여 99%이상의 상동성을가지는 7균주의 Bacillus sp.균주들과 15균주 Pseudomonas sp.균주들로 동정할 수 있었다. 한편, 이들 중 다기능 사구식물생장촉진 근권세균인 Pseudomonas fluorescens IB4-14는 고염, 건조와 같은 환경스트레스에 저항성을 가질 수 있게 하는 ACC deaminase를 생산하므로써 식물생장촉진은 물론이고, 환경스트레스 저항성 기작을 가지는 다중기능 균주이었다. 또한, 선발된 옥신생산성 다기능 균주인 P. fluorescens IB4-14는 사구식물인 갯까치수영의 종자발아능과 뿌리생장촉진능에서 우수한 생육촉진능을 발휘함을 확인하였으므로 사구식물 복원에 사용할 미생물제제의 구성균주로 선발되었다고 생각한다.

• 한국미생물·생명공학회지
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• 제40권3호
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• pp.190-196
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• 2012

식물생장 촉진 홀몬 auxin을 생산하는 균주를 선발하기 위해 경북 경산시 소재 고추경작지 근권토양으로 부터 739종의 일반호기성 균주와 urease 생산 균주 80종 및 광합성 균주 303종과 같이 총 1000여종 이상의 균주를 분리하였다. 이 균주들을 대상으로 Salkowski test를 실시한 결과, auxin을 생산하는 158종의 일반호기성 균주와 70종의 urease 생산 균주 및 228종의 광합성 균주를 선발할 수 있었으며, Holbrook test를 통해 또 다른 식물생장 촉진 호르몬인 gibberellin도 대부분의 균주에서 생산되는 것을 확인할 수 있었다. 선발된 균주 중 항진균 물질인 ${\beta}$-Glucanase와 siderophore를 생산하고 다양한 병원성 진균에 대해 길항 범위를 가지는 6가지 균주 BCB14, BCB17, C10, HA46, HA143, HJ5를 toothpicking 및 대치배양을 통해 최종 선발할 수 있었으며, 분류학적으로 동정한 결과 6종 모두 B. subtilis BCB14, B. methylotrophicus BCB17, B. methylotrophicus C10, B. sonorensis HA46, B. subtilis HA143, B. safensis HJ5로 확인되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.885-893
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• 2001

This review summarizes some recent research into ways of improving the productivity of ruminal fermentation by increasing protein flow from the rumen and decreasing the breakdown of protein that results from the action of ruminal microorganisms. Proteinases derived from the plant seem to be of importance to the overall process of proteolysis in grazing animals. Thus, altering the expression of proteinases in grasses may be a way of improving their nutritive value for ruminants. Inhibiting rumen microbial activity in ammonia formation remains an important objective: new ways of inhibiting peptide and amino acid breakdown are described. Rumen protozoa cause much of the bacterial protein turnover which occurs in the rumen. The major impact of defaunation on N recycling in the sheep rumen is described. Alternatively, if the efficiency of microbial protein synthesis can be increased by judicious addition of certain individual amino acids, protein flow from ruminal fermentation may be increased. Proline may be a key amino acid for non-cellulolytic bacteria, while phenylalanine is important for cellulolytic species. Inhibiting rumen wall tissue breakdown appears to be an important mechanism by which the antibiotic, flavomycin, improves N retention in ruminants. A role for Fusobacterium necrophorum seems likely, and alternative methods for its regulation are required, since growth-promoting antibiotics will soon be banned in many countries.

• Preventive Nutrition and Food Science
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• 제7권3호
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• pp.332-345
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• 2002

It is a recent observation that about 80 per cent of the body's immune system is localized in the gastrointestinal tract. This explains to a large extent why eating right is important for the modulation the immune response and prevention of disease. In addition it is increasingly recognized that the body has an important digestive system also in the lower gastrointestinal tract where numerous important substances are released by microbial enzymes and absorbed. Among these substances are short chain fatty acids, amino acids, various carbohydrates, poly-amines, growth factors, coagulation factors, and many thousands of antioxidants, not only traditional vitamins but numerous flavonoids, carotenoids and similar plant- and vegetable produced antioxidants. Also consumption of health-promoting bacteria (probiotics) and vegetable fibres (prebiotics) from numerous sources are known to have strong health-promoting influence. It has been calculated that the intestine harbours about 300,000 genes, which is much more than the calculated about 60,000 for the rest of the human body, indicating a till today totally unexpected metabolic activity in this part of the GI tract. There are seemingly several times more active enzymes in the intestine than in the rest of the body, ready to release hundred thousand or more of substances important for our health and well-being. In addition do the microbial cells produce signal molecules similar to cytokines but called bacteriokines and nitric oxide, with provide modulatory effects both on the mucosal cells, the mucosa- associated lymphoid system (MALT) and the rest of the immune system. Identification of various fermentation products, and often referred to as synbiotics, studies of their role in maintaining health and well-being should be a priority issue during the years to come.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2001년도 International Symposium on Food,Nutrition and Health for 21st Century
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• pp.187-231
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• 2001

It is a recent observation that about 80 per cent of the body's immune system is localized in the gastrointestinal tract. This explains to a large extent why eating right is important for the modulation the immune response and prevention of disease. I addition it is increasingly recognized that the body has an important digestive system also in the lower gastrointestinal tract where numerous important substances are released by microbial enzymes and absorbed. Among these substances are short chain fatty acids, amino acids, various carbohydrates, polyamines, growth factors, coagulation factors, and many thousands of antioxidants, not only traditional vitamins but numerous flavonoids, carotenoids and similar plant- and vegetable produced antioxidants. Also consumption of health-promoting bacteria (probiotics) and vegetable fibres (prebiotics) from numerous sources are known to have strong health-promoting influence. It has been calculated that the intestine harbours about 300 000 genes, which is much more than the calculated about 60000 for the rest of the human body, indicating a till today totally unexpected metabolic activity in this part of the GI tract. There are seemingly several times more active enzymes in the intestine than in the rest of the body, ready to release hundred thousand or more of substances important for our health and well-being. In addition do the microbial cells produce signal molecules similar to cytokines but called bacteriokines and nitric oxide, with provide modulatory effects both on the mucosal cells, the mucosa-associated lymphoid system (MALT) and the rest of the immune system. Identification of various fermentation products, and often referred to as synbiotics, studies of their role in maintaining health and well-being should be a priority issue during the years to come.

• 한국토양비료학회지
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• 제45권1호
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• pp.51-58
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• 2012

Salinity is one of the most relevant abiotic factor limiting crop yield and its net primary productivity. In addition, salinity induces an increased stress ethylene synthesis in plants which, in turn, exacerbate the responses to the stressor. Bacterial single or co-inoculation effect was tested using previously characterized plant growth promoting (PGP) bacteria Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 on maize and sorghum-sudan grass hybrid under different concentrations of NaCl. Non-inoculated maize and sorghum-sudangrass hybrid showed 33.4% and 20.0% reduction in seed germination under highest NaCl (150 mM) level tested. However, under the same NaCl concentration, co-inoculation with B. iodinum RS16 and M. oryzae CBMB20 PGP strains increased the seed germination in maize (16.7%) and sorghum-sudangrass hybrid (4.4%). In Gnotobiotic growth pouch experiments conducted for maize and sorghum-sudangrass hybrid, co-inoculation of PGP B. iodinum RS16 and M. oryzae CBMB20 mitigated the salinity stress and promoted root length by 22.9% and 29.7%, respectively. Thus the results of this study could help in development of potential bioinoculants that may be suitable for crop production under saline conditions.