• 한국균학회소식:학술대회논문집
• /
• 한국균학회 2018년도 춘계학술대회 및 임시총회
• /
• pp.33-33
• /
• 2018

Air-borne plant pathogenic fungus Fusarium graminearum and seed-borne plant pathogenic bacterium Burkholderia glumae are cause similar disease symptoms in rice heads. Here we showed that two pathogens frequently co-isolated in rice heads and F. graminearum is resistant to toxoflavin produced by B. glumae while other fungal genera are sensitive to the toxin. We have tried to clarify the resistant mechanism of F. graminearum against toxoflavin and the ecological reason of co-existence of the two pathogens in rice. We found that F. graminearum carries resistance to toxoflavin as accumulating lipid in fungal cells. Co-cultivation of two pathogens resulted in increased conidia and enhanced chemical attraction and attachment of the bacterial cells to the fungal conidia. Bacteria physically attached to fungal conidia, which protected bacterium cells from UV light and allowed disease dispersal. Chemotaxis analysis showed that bacterial cells moved toward the fungal exudation compared to a control. Even enhanced the production of phytotoxic trichothecene by the fungal under presence of toxoflavin and disease severity on rice heads was significantly increased by co-inoculation rather than single inoculation. This study suggested that the undisclosed potentiality of air-born infection of bacteria using the fungal spores for survival and dispersal.

• 식물병연구
• /
• 제27권4호
• /
• pp.129-136
• /
• 2021

벼는 전 세계 30억 인구의 식량 공급원으로 아시아 인구의 약 절반이 쌀을 식량자원으로 의존하며 100개 이상의 국가에서 재배되고 있다. 따라서 벼의 병해충에 따른 경제적 손실과 수확량 감소는 식량 수요와 공급을 위협할 수 있다. 벼에 발생하는 병해충을 방제하기 위해 가장 일반적으로 사용되는 방법은 농약을 통한 화학적 방제이다. 그러나 이러한 농약을 통한 환경 오염, 잔류 독성, 내성 병원균 출현, 토양 품질 저하 및 생물 다양성 파괴 등의 문제를 야기할 수 있다. 벼의 병해를 방제하기 위한 최근의 대안으로 미생물을 포함한 환경친화적인 생물학적 방제에 대한 연구가 활발히 진행되고 있다. 미생물 작용제는 식물 병원균과의 경쟁, 항생제 효과 및 기생을 통해 식물 병을 방제 할 수 있다. 벼 근권에서 분리한 미생물들, 예를들어 Bacillus spp., Pseudomonas spp., Trichoderma sp. 등은 벼에 발생하는 다양한 곰팡이 및 세균 병들에 대한 생물 방제제로 사용가능성이 보고되었는데, 특히 벼도열병, 벼 잎집무늬마름병, 벼 흰잎마름병, 벼 깨씨무늬병 및 벼 키다리병을 방제하는 것으로 보고되었다. 이 리뷰에서는 벼에 발생하는 다양한 병에 대한 생물 방제제로서 미생물들이 적용된 연구들에 대하여 논의하였다.

• Journal of Microbiology and Biotechnology
• /
• 제28권9호
• /
• pp.1527-1535
• /
• 2018

Bacterial strain BAS23 was isolated from rice field soil and identified as Bacillus amyloliquefaciens. Based on dual culture method results, the bacterium BAS23 exhibited potent in vitro inhibitory activity on mycelial growth against a broad range of dirty panicle fungal pathogens of rice (Curvularia lunata, Fusarium semitectum and Helminthosporium oryzae). Cell-free culture of BAS23 displayed a significant effect on germ tube elongation and mycelial growth. The highest dry weight reduction (%) values of C. lunata, H. oryzae and F. semitectum were 92.7%, 75.7%, and 68.9%, respectively. Analysis of electrospray ionization-mass spectrometry (ESI-MS) and $^1H$ nuclear magnetic resonance (NMR) spectroscopy revealed that the lipopeptides were iturin A with a C14 side chain (C14 iturinic acid), and a C15 side chain (C15 iturinic acid), which were produced by BAS23 when it was cultured in nutrient broth (NB) for 72 h at $30^{\circ}C$. BAS23, the efficient antagonistic bacterium, also possessed in vitro multiple traits for plant growth promotion and improved rice seedling growth. The results indicated that BAS23 represents a useful option either for biocontrol or as a plant growth-promoting agent.

• The Plant Pathology Journal
• /
• 제29권4호
• /
• pp.446-450
• /
• 2013

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

• The Plant Pathology Journal
• /
• 제31권2호
• /
• pp.152-164
• /
• 2015

Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and $YC7010^T$, with antimicrobial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208) and Burkholderia glumae (KACC 44022), respectively, were also suppressed effectively by drenching a bacterial suspension ($10^7cfu/ml$) of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC $15859^T$ (99.67%), Bacillus methylotrophicus KACC $13105^T$ (99.65%), Bacillus amyloliquefaciens subsp. plantarum KACC $17177^T$ (99.60%), and Bacillus tequilensis KACC $15944^T$ (99.45%). The DNA-DNA relatedness value between strain $YC7010^T$ and the most closely related strain, B. siamensis KACC $15859^T$ was $50.4{\pm}3.5%$, but it was $91.5{\pm}11.0%$ between two strains YC7007 and $YC7010^T$, indicating the same species. The major fatty acids of two strains were anteiso-$C_{15:0}$ and iso $C_{15:0}$. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the two strains YC7007 and $YC7010^T$ represent novel species of the genus Bacillus, for which the name Bacillus oryzicola sp. nov. is proposed. The type strain is $YC7010^T$ (= KACC $18228^T$). Taken together, our findings suggest that novel endophytic Bacillus strains can be used for the biological control of rice diseases.

• 한국식물병리학회지
• /
• 제14권4호
• /
• pp.345-349
• /
• 1998

Fifty isolates of myxobacteria were isolated from soils from several areas in Korea during 1996-1997 and bioactivity against plant pathogenic fungi of these isolates was examined. A myxobacterial isolate KR025 showed good antifungal activities against Pyricularia oryzae, Cryphonectria parasitica, Colletotrichum lagenarium, and C. gloeosporioides but did not against Rhizoctonia solani, Fusarium oxysporum and Pythium ultimum. The bacterium was identified as Myxococcus fulvus based on morphological and physiological characteristics. Antifungal substances were extracted from culture broth and bacterial cell of Myxococcus fulvus KR025 by ethyl acetate. Antifungal substance of Myxothiazole (100 ${\mu}{\textrm}{m}$/ml) produced by Myxococcus fulvus KR 025 controlled 97.0% rice blast, tomato late blight, wheat leaf rust, and barley powdery mildew and showed 45.0 and 82.6% disease control of rice sheath blight and cucumber gray model, respectively.

• 한국축산식품학회지
• /
• 제27권3호
• /
• pp.371-376
• /
• 2007

본 연구에서는 상황미 추출물을 이용하여 병원성 식중독 균(S aureus 305, L. monocytogenes ATCC 19114, E. coli 0157:H7 ATCC 42894, E. coli O55)에 대한 항균효과와 human rotavirus(KU, S2, YO, K-21)에 대한 억제효과를 알아보기 위해서 수행되었다. 그 결과는 다음과 같다. 항균성 테스트에서 S. aureus 305는 18mm, L. monocytogenes ATCC 19114는 20 mm, E. coli O55는 13mm의 inhibition zone이 생성되었으나, E. coli O157:H7 ATCC 42894는 inhibition zone이 생성되지 않았다. MTT assay 방법에 따라 실시한 l/3% 상황미 추출물의 human rotavirus에 대한 억제효과는 K-21이 $97.56{\pm}12.50%$, S2가 $94.74{\pm}8.68%$ YO가 $59.77{\pm}8.68%$, KU가 $90.52{\pm}18.42%$로 각각 나타났다. 이러한 결과로 보아 상황미 추출물은 병원성 식중독균과 다양한 유아 rotavirus 모두에게 억제 효과가 있는 것으로 확인되었다.

• The Plant Pathology Journal
• /
• 제37권2호
• /
• pp.173-181
• /
• 2021

The genus Streptomyces demonstrates enormous promise in promoting plant growth and protecting plants against various pathogens. Single and consortium treatments of two selected Streptomyces strains (Streptomyces shenzhenensis TKSC3 and Streptomyces sp. SS8) were evaluated for their growth-promoting potential on rice, and biocontrol efficiency through induced systemic resistance (ISR) mediation against Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of rice bacterial leaf streak (BLS) disease. Seed bacterization by Streptomyces strains improved seed germination and vigor, relative to the untreated seed. Under greenhouse conditions, seed bacterization with consortium treatment TKSC3 + SS8 increased seed germination, root length, and dry weight by 20%, 23%, and 33%, respectively. Single and consortium Streptomyces treatments also successfully suppressed Xoc infection. The result was consistent with defense-related enzyme quantification wherein single and consortium Streptomyces treatments increased peroxidase (POX), polyphenol oxidase, phenylalanine ammonia-lyase, and β,1-3 glucanase (GLU) accumulation compared to untreated plant. Within all Streptomyces treatments, consortium treatment TKSC3 + SS8 showed the highest disease suppression efficiency (81.02%) and the lowest area under the disease progress curve value (95.79), making it the best to control BLS disease. Consortium treatment TKSC3 + SS8 induced the highest POX and GLU enzyme activities at 114.32 µmol/min/mg protein and 260.32 abs/min/mg protein, respectively, with both enzymes responsible for plant cell wall reinforcement and resistant interaction. Our results revealed that in addition to promoting plant growth, these Streptomyces strains also mediated ISR in rice plants, thereby, ensuring protection from BLS disease.

• 한국미생물·생명공학회지
• /
• 제44권1호
• /
• pp.98-105
• /
• 2016

강원도를 비롯한 전국에서 발효식품 44점으로부터 유해균에 대한 생육억제 활성이 우수한 고초균주를 분리 및 동정하였으며, 생육억제 활성이 가장 우수하였던 Bacillus amyloliquefaciens MBE1283로 명명된 균주의 유해균에 대한 생육억제 활성, 전분분해 효소활성 및 생육특성을 조사하였다. Escherichia coli O157:H7 KCCM40406을 비롯한 8종류의 유해균에 대한 생육억제 활성을 평가한 결과, 막걸리에서 분리된 B. amyloliquefaciens MBE1283 균주는 다른 B. amyloliquefaciens 균주들에 비해 유의적으로 높은 유해균 생육억제 활성을 나타내었다. B. amyloliquefaciens MBE1283 균주의 ${\alpha}$-amylase 효소활성은 대조구 균주들과 비교하였을 때 현저히 낮았으나 glucoamylase 효소활성은 대조구로 사용한 균주와 유사한 수준이었다. B. amyloliquefaciens MBE1283 균주의 최적 생육온도는 $45^{\circ}C$로서 대조구 균주보다 온도에 대한 내성이 있는 것으로 판단되었으며, 균체 성장에 적합한 최적 배지는 pH 6이었다. 본 연구를 통하여 막걸리로부터 분리된 B. amyloliquefaciens MBE1283 균주는 여러 종류의 유해균에 항균활성을 지니며 높은 온도와 낮은 pH에 대하여 내성을 지닌 것을 알 수 있었다.

• 한국미생물·생명공학회지
• /
• 제40권1호
• /
• pp.39-42
• /
• 2012

벼흰잎마름병을 억제하는 물질의 활성을 확인하기 위하여 벼 잎 생엽절편을 이용하는 새로운 스크리닝 방법을 개발하였다. 96 well plate에 잔토모나스 오라이자의 배양액을 분주하고 균등한 크기의 벼 잎 생엽절편을 배치한 후 효능을 확인하고자 하는 물질을 처리하였다. 흰잎마름병균을 억제하는 물질의 활성도는 벼 잎 생엽절편 병징의 면적율로 환산되었다. 물질에 의하여 병의 발생이 억제된 벼 잎 생엽절편은 병원균 배양액 내에서 건전한 녹색을 유지하였고 병이발생된 벼 잎 생엽절편은 황갈색 병징을 나타내었다. 이를 통하여 본 실험법이 빠르고 간편하며, 농도 의존적인 활성확인이 가능하고, 소량으로 다수 물질의 활성 여부를 동시에 평가할 수 있음을 확인하였다. 본 스크리닝 법은 벼흰잎마름병 뿐만 아니라 여타의 수인성 작물질병억제 활성을 확인하는 데 응용 가능성이 있을 것으로 생각된다.