• Journal of Ginseng Research
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• 제38권2호
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• pp.136-145
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• 2014

Background: This study aimed to develop a biocontrol system for ginseng root rot caused by Fusarium cf. incarnatum. Methods: In total, 392 bacteria isolated from ginseng roots and various soils were screened for their antifungal activity against the fungal pathogen, and a bacterial isolate (B2-5) was selected as a promising candidate for the biocontrol because of the strong antagonistic activity of the bacterial cell suspension and culture filtrate against pathogen. Results: The bacterial isolate B2-5 displayed an enhanced inhibitory activity against the pathogen mycelial growth with a temperature increase to $25^{\circ}C$, produced no pectinase (related to root rotting) an no critical rot symptoms at low [$10^6$ colony-forming units (CFU)/mL] and high ($10^8CFU/mL$) inoculum concentrations. In pot experiments, pretreatment with the bacterial isolate in the presumed optimal time for disease control reduced disease severity significantly with a higher control efficacy at an inoculum concentration of $10^6CFU/mL$ than at $10^8CFU/mL$. The establishment and colonization ability of the bacterial isolates on the ginseng rhizosphere appeared to be higher when both the bacterial isolate and the pathogen were coinoculated than when the bacterial isolate was inoculated alone, suggesting its target-oriented biocontrol activity against the pathogen. Scanning electron microscopy showed that the pathogen hyphae were twisted and shriveled by the bacterial treatment, which may be a symptom of direct damage by antifungal substances. Conclusion: All of these results suggest that the bacterial isolate has good potential as a microbial agent for the biocontrol of the ginseng root rot caused by F. cf. incarnatum.

• 한국식물병리학회지
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• 제1권1호
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• pp.17-21
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• 1985

비병원성 Pseudomonas solanacearum을 이용한 담배세균성마름병의 방제가능성이 검토되었다. Nutrient 액체배지 및 토양에서 비병원성균주는 병원성균주보다 생육속도가 빨랐으나 두 균주를 혼합하여 배양할 때 병원성균주에 대한 생육억제효과는 크지 않았다. 비병원성균주의 현탁액에 감수성 담배품종인 BY4의 뿌리를 6시간동안 침지시킨 후 병원성균주에 오염된 토양으로 이식한 결과, 높은 세균성마름병 방제효과를 얻었다. 비병원성균주의 현탁액을 가식상태의 담배에 토양관주하고 24시간 후에 포장으로 이식한 결과 7월 상순까지는 $30\%$이상의 세균성마름병방제효과가 인정되었으나 그 후 방제효과가 급속히 감소되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권2호
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• pp.199-202
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• 2004

Cellulolytic bacterial strains have been isolated from the faeces of wild (blackbuck, Antilope cervicapra; nilgai, Baselophus tragocamelus chinkara, Gazella gazella spotted deer, Axis axis and hog deer, Cervus porcinus) and rumen liquor of domestic (sheep, Ovis aries) ruminants. Five best cellulose degrading bacterial isolates (Ruminococcus sp.) were used as microbial feed additive along with buffalo rumen liquor as inoculum to study their effect on digestibility of feed and enzyme production in in vitro conditions. The bacterial isolate from chinkara (CHI-2) showed the highest per cent apparent dry matter (DM) digestibility ($35.40{\pm}0.60$), true dry matter digestibility ($40.80{\pm}0.69$) and NDF ($26.38{\pm}0.83$) digestibility (p<0.05) compared to control ($32.73{\pm}0.56$, $36.64{\pm}0.71$ and $21.16{\pm}0.89$, respectively) and other isolates at 24 h of incubation with lignocellulosic feeds (wheat straw and wheat bran, 80:20). The same isolate also exhibited the highest activities of fibre degrading enzymes like carboxymethylcellulase, xylanase, ${\beta}$-glucosidase and acetyl esterase. The bacterial isolate from chinkara (Gazella gazella) appears to have a potential to be used as feed additive in the diet of ruminants for improving utilization of nutrients from lignocellulosic feeds.

• 한국응용곤충학회지
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• 제16권4호
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• pp.235-239
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• 1977

선발에 의하여 얻은 벼 흰빛잎마름병균 Xanthomonas oryzae의 Streptomycin 내성균에 대하여 병원성, 배지내에서의 생장량 및 자외선 감수성에 대한 변이성을 조사하여 다음과 같은 결과를 얻었다. (1) SM 내성균은 Wase-Aikoku-3, Rant Emas-2 황옥 및 Kimmase의 4개 판별품종에 대한 병원성 비교에서 75-6의 내성균주가 황옥에 대하여 감수성 반응이 모균과 달리 중정도의 저항성을 나타내었다. 2) SM-내성균은 정상배지에서 모균보다 약간 높은 생장량을 보였고 100ug/ml Agrepto 첨가 배지에서는 접종후 60시간까지 생장이 조지되었으나 70시간 이후에는 모균의 생장량을 능가하였다. (3) SM-내성균은 254mu 파장의 자외선 조사에서 모균과 동일한 감수성을 나타내어 내성인자는 안정된 것으로 생각되었다.

• Parasites, Hosts and Diseases
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• 제35권2호
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• pp.127-134
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• 1997

콘택트렌즈 보존 용기 유래 가시아메바 KA/LS주의 세포질 내에 존재하는 bacterial endosymbiont(내공생세균)를 투과전자현미경으로 관찰하여 확인하였다. 숙주인 가시아메바 KA/LS주는 형태학적으로 제2군에 속하였고 rDNA PCR-RFLP 결과 A. lugdunensis로 동정되었다. 미토콘드리아 DNA RFLP와 동위효소 분석상 이 충주는 국내 콘택트렌즈 보존용기에서 가장 흔히 분리되는 type인 KA/L1주, 국내 임상 분리주 중 하나인 KA/E2주, 내공생세균을 가지는 것으로 보고된 병원 냉각수 유래 KA/W4주 및 L3a주와 동일하거나 매우 유사한 성적을 보였다. 내 공생세균은 약 $1.38{\;}{\times}{\;}0.50{\;}{\mu\textrm{m}}$의 크기였고, 아메바 세포질 내에 불규칙하게 분포하고 있었으며 그 표면에 아메바의 ribosome이 부착되어 있었다. 내공생세균을 둘러싼 lacunae나 막과 같은 구조는 관찰되지 않았다. Legionoun 특이 primer를 이용한 효소중합반응(PCR)에서 내공생세균의 염색체 DNA는 증폭되지 않았다 A. lugdunensis의 우리말 이름을 담수가시아메바로 제안한다.

• 한국식물병리학회지
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• 제2권2호
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• pp.114-120
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• 1986

BY4품종의 담배를 포장에 이식하면서 이식 하루전과 40일 후에 비병원성 Pseudomonas solanacearum의 현탁액을 담배근권토양에 관주한 결과 7월 상순까지 세균성마름병 발생 속도가 지연되었으나 그 후에는 방제효과가 급속히 감소되었다. 그 결과 잎담배의 $35\%$ 증수 및 kg당 대금으로 $10\%$의 품질상승 효과를 얻을 수 있었다. 비병원성균주처리에 의한 근권상양내 병원균의 밀도증가억제는 인정되지 않았다. $^{32}P$로 표식된 비병원성균주의 담배뿌리를 통한 침입 및 식물체내 이동이 확인되었으며 비병원성균주에 전접종된 담배에 대하여 병원성균주의 침입 및 식물체내 증식이 억제되었다. 이러한 병원성균주의 식물체내 침입 및 증식억제 현상이 병진전 억제와 관련이 있는 것으로 생각되었다.

• Journal of Microbiology and Biotechnology
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• 제30권10호
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• pp.1500-1509
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• 2020

Drought is a major abiotic factor and has drastically reduced crop yield globally, thus damaging the agricultural industry. Drought stress decreases crop productivity by negatively affecting crop morphological, physiological, and biochemical factors. The use of drought tolerant bacteria improves agricultural productivity by counteracting the negative effects of drought stress on crops. In this study, we isolated bacteria from the rhizosphere of broccoli field located in Daehaw-myeon, Republic of Korea. Sixty bacterial isolates were screened for their growth-promoting capacity, in vitro abscisic acid (ABA), and sugar production activities. Among these, bacterial isolates YNA59 was selected based on their plant growth-promoting bacteria traits, ABA, and sugar production activities. Isolate YNA59 highly tolerated oxidative stress, including hydrogen peroxide (H₂O₂) and produces superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities in the culture broth. YNA59 treatment on broccoli significantly enhanced plant growth attributes, chlorophyll content, and moisture content under drought stress conditions. Under drought stress, the endogenous levels of ABA, jasmonic acid (JA), and salicylic acid (SA) increased; however, inoculation of YNA59 markedly reduced ABA (877 ± 22 ng/g) and JA (169.36 ± 20.74 ng/g) content, while it enhanced SA levels (176.55 ± 9.58 ng/g). Antioxidant analysis showed that the bacterial isolate YNA59 inoculated into broccoli plants contained significantly higher levels of SOD, CAT, and APX, with a decrease in GPX levels. The bacterial isolate YNA59 was therefore identified as Variovorax sp. YNA59. Our current findings suggest that newly isolated drought tolerant rhizospheric Variovorax sp. YNA59 is a useful stress-evading rhizobacterium that improved drought-stress tolerance of broccoli and could be used as a bio-fertilizer under drought conditions.

• Applied Biological Chemistry
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• 제48권3호
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• pp.296-300
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• 2005

Among the root colonizing and plant growth promoting bacteria isolated from the bacterial wilt suppressive soil, five strains were detected to produce siderophores by CAS agar assay. The most effective isolate, TS3-7 strain induced significant suppression of bacterial wilt disease in tomato and pepper plants. Seed treatment followed by soil drench application with this strain resulted in over 80% reduction of bacterial wilt disease compared with the control. Significant disease suppression by TS3-7 strain was related to the production of siderophore. Besides iron competition, induction of resistance of the host plant with siderophore was suggested to be another mode of action that suppress bacterial wilt, based on the lack of direct antibiosis against pathogen in vitro. According to Bergey's Manual of Systemic Bacteriology and 16S rDNA sequence data, TS3-7 stain was identified as Pseudomonas sp. TS3-7.

• Journal of Microbiology
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• 제35권4호
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• pp.284-289
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• 1997

A Gram (-), rod-shaped bacterium $2.3{\sim}2.8{\times}0.45{\mu}m$ in size which exhibited growth-inhibiting effects against a cyanobacterium (Anabaena cylindrica) was isolated from Daechung Dam Reservoir. This isolate was identified as Moraxella sp. and designated Moracella sp. CK-1. Hollow zones formed around bacterial colonies on the cyanobacterial lawn. In a mixed-culture of A. cylindrica and the isolate, each microorganism grew inverse-proportionally, and the cyanobacterial vegetative cells completely disappeared within 24 hours. On treatment with Moraxella sp. CK-1, cell walls of A. cylindrica disappeared, but sheathes remained in a more electron dense form. The unit membrane such as thylakoidal membrane was stable to bacterial lysing activity. This bacterium showed a broad action spectrum against cyanobacteria. The growth-inhibiting activity of Moracella sp. CK-1 against A. cylindrica is believed to be performed through the excretion of active substances.

• 한국연초학회지
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• 제24권1호
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• pp.7-12
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• 2002

During the screening or antiviral substances having inhibitory effect on tobacco mosaic virus(TMV) infection to tobacco plants, we found that a bacterial isolate, KTB61, which was identified as a Pseudomonas sp., strongly inhibited the formation of TMV local lesions. When the culture filtrate from KTB61 was applied on the upper surface of leaves of N. tabaccum Xanthi-nc tobacco at the same time of or 24 hours before TMV inoculation, almost complete inhibition was achieved. Incidence of systemic TMV infection to the susceptible tobacco cultivar, NC82, was reduced by 95% when TMV was inoculated onto the upper surface of leaves 24 hours after spraying the culture filtrate. Also 75∼80% of inhibitory effect was obtained by the inoculation of TMV onto the under surface of the leaves treated with culture filtrate 24 hours beforehand. In field trials, the TMV infection was reduced by 96.5% when the tobacco seedlings, N. tabaccum cv. NC82, were soaked with culture filtrate before transplanting.