• Journal of Plant Biotechnology
• /
• 제37권3호
• /
• pp.327-336
• /
• 2010

Cysteine proteases have been known as a critical factor in plant defense mechanisms in pineapple, papaya, or wild fig. Papain or ficin is one kind of cysteine proteases that shows toxic effects to herbivorous insects and pathogenic bacteria. However, resistance to bacterial soft rot of plants genetically engineered with cysteine protease has been little examined thus far. We cloned a cysteine protease cDNA from Ananas comosus and introduced the gene into Chinese cabbage (Brassica rapa) under the control of the cauliflower mosaic virus 35S promoter. The transgene was stably integrated and actively transcribed in transgenic plants. In comparisons with wild-type plants, the $T_2$ and $T_3$ transgenic plants exhibited a significant increase in endo-protease activity in leaves and enhanced resistance to bacterial soft rot. A cDNA microarray analysis revealed that several genes were more abundantly transcribed in the transgenic than in the wild type. These genes encode a glyoxal oxidase, PR-1 protein, PDF1, protein kinase, LTP protein, UBA protein and protease inhibitor. These results suggest an important role for cysteine protease as a signaling regulator in biotic stress signaling pathways, leading to the build-up of defense mechanism to pathogenic bacteria in plants.

• Journal of Microbiology and Biotechnology
• /
• 제16권7호
• /
• pp.1060-1067
• /
• 2006

This study was undertaken to determine the effect of reservoirs on water quality and the distribution of pathogenic and indicator bacteria in a drinking water distribution system (total length 14km). Raw water, disinfected water, and water samples from the distribution system were subjected to physicochemical and microbiological analyses. Most factors encountered at each season included residual chloride, nitrate, turbidity, and phosphorus for heterotrophic bacterial distribution, and hardness, heterotrophic bacteria, sampling site, and DOC (dissolved organic carbon) for bacteria on selective media. No Salmonella or Shigella spp. were detected, but many colonies of opportunistic pathogens were found. Comparing tap water samples taken at similar distances from the water treatment plant, samples that had passed through a reservoir had a higher concentration of heterotrophic bacteria, and a higher rate of colony formation with 10 times as many bacteria on selective media. Based on the results with m-Endo agar, the water in reservoirs appeared safe; however, coliforms and opportunistic pathogenic bacteria such as Pseudomonas aeruginosa were identified on other selective media. This study illustrates that storage reservoirs in the drinking water distribution system have low microbiological water quality by opportunistic pathogens, and therefore, water quality must be controlled.

• The Plant Pathology Journal
• /
• 제28권1호
• /
• pp.20-31
• /
• 2012

Endophytic bacterial communities of tidal flat plants antagonistic to oomycete plant pathogens were studied by the isolation of 256 root colonizing endophytic bacteria from surface-disinfected root tissues of six plants ($Rosa$ $rugosa$, $Suaeda$ $maritima$, $Vitex$ $rotundifolia$, $Carex$ $scabrifolia$, $Glehnia$ $littoralis$ and $Elymus$ $mollis$) growing in a tidal flat area of Namhae Island, Korea. To understand the antagonistic potential, an $in$ $vitro$ antagonistic assay was performed to characterize and identify strains that were antagonistic to the oomycete plant pathogens $Phytophthora$ $capsici$ and $Pythium$ $ultimum$ from the total population. Nine percent of the total number of isolated bacteria exhibited in vitro inhibitory activity against target plant pathogenic oomycetes. Taxonomic and phylogenetic placement of the antagonistic bacteria was investigated by analysis of the 16S rRNA gene sequences. The sequence analysis classified the antagonistic strains into four major classes of the domain bacteria ($Firmicutes$, ${\alpha}-Proteobacteria$, ${\gamma}-Proteobacteria$ and $Actinomycetes$) and 10 different genera. Further production of secondary metabolites, hydrolytic enzymes and plant growth promoting traits were determined for the putative new species of antagonistic endophytic bacteria. These new strains could not be identified as known species of ${\alpha}-Proteobacteria$, and so may represent novel bacterial taxa. The unexpected high antagonistic bacterial diversity associated with the tidal flat plants may be indicative of their importance in tidal flat plants as a promising source of novel antimicrobial compounds and biocontrol agents.

• The Plant Pathology Journal
• /
• 제19권1호
• /
• pp.43-45
• /
• 2003

Soft rot symptom was observed on lily bulb in the fields and at a low temperature storage house from 1999 to 2000 in Korea. The small dark-brown lesion appeared on the bulb, and enlarged and developed into the inner scales of the bulb. The bulb became water soaked and gave out unpleasant odor. Two different pathogenic bacteria were isolated from infected tissues. The causal bacteria were identified as Pectobacterium carotovorum subsp. carotovorum (Erwinia carotovora subsp. carotovora) and Pseudomonas marginalis based on bacteriological characteristics. Pathogenicity of the bacteria was proven by Koch's postulations. This is the first report of bacterial soft rot of lily bulb in Korea caused by the two bacteria.

• 한국버섯학회지
• /
• 제9권2호
• /
• pp.87-89
• /
• 2011

뽕나무병원성세균에 대한 Beaveria bassiana 6균주의 항균활성을 paper disc법으로 조사하였고 최소성장저해농도(MIC)를 액체배지희석법으로 조사하였다. 항균활성은 B. bassiana J200에서만 나타났으며, Erwinia rhapontici KACC 10407에서는 13mm, Pseudomonas syringae KACC 10390와 Xanthomonas campestris KACC 12134에서는 각각 17 mm의 항균활성이 나타났다. MIC 측정 결과 E. rhapontici KACC 10407, P. syringae KACC 10390 및 X. campestris KACC 12134 모두 4.0%에서 MIC를 보였다. 이상의 결과로 B. bassiana의 뽕나무병원성세균에 대한 생물학적 방재제로서의 이용 가능성을 확인하였다.

• 한국임상수의학회지
• /
• 제24권2호
• /
• pp.130-136
• /
• 2007

Artemisia capillaris THUNB is a perennial herb that belongs to the family Compositae spp and the most common plant among the various herbal folk remedies used in treatment of abdominal pain, hepatitis, chronic liver disease, jaundice and coughing in Korea. In this study, antimicrobial effects of Artemisia capillaris extracts on the food poisoning bacteria were investigated for further clinical application, which is an alternative for the use of antibiotics and their unexpected resistance. Artemisia capillaris extract using ethyl acetate showed the highest antimicrobial effects on S. enteritidis, E. coli O157 : H7, L. monocytogenes and S. aureus. The chloroform extract showed strong effects on all kinds of bacteria; whereas ethanol and methanol extracts showed weaker effects. Finally, ether and water extracts showed the weakest effects under the same conditions. The minimum inhibitory concentration (MIC) of ethyl acetate extract was 1 mg/mL for E. coli O157 : H7 and L. monocytogenes, and 2 mg/mL for S. enteritidis and S. aureus. The inhibitory effects on all the bacteria continued for 12 hours after incubation using 20 mg/mL and 30 mg/mL of ethyl acetate extract. The inhibitory effects continued maximally for 72 hours. The results of these studies indicate Artemisia capillaris extract exhibited excellent antimicrobial and inhibitory effects on the food poisoning pathogenic bacteria; S. enteritidis, E. coli O157 : H7, L. monocytogenes and S. aureus.

• The Plant Pathology Journal
• /
• 제34권5호
• /
• pp.403-411
• /
• 2018

This study takes strawberry-fruits as the test material and discusses the effect of Burkholderia contaminans B-1 on preventing postharvest diseases and inducing resistance-related substances in strawberry-fruits. Soaking and wound inoculating is performed to analyze the inhibitory effects of different treatment solutions on the gray mold of postharvest strawberry-fruits. The count of antagonistic bacteria colonies in the wound is found, and the dynamic growth of antagonistic bacteria and the pathogenic fungus is observed by electron microscopy. The results indicated that, either by soaking/wound-inoculating, the fermentation and suspension of antagonistic bacteria significantly reduced the incidence of postharvest diseases of strawberry-fruits. With wound inoculation, the inhibition rate of antagonist fermentation and suspension ($1{\times}10^{10}cfu/ml$) respectively reached 77.4% and 66.7%. It also led to a significant increase in the activity of resistance-related enzymes, i.e., phenylalanine ammonia lyase (PAL), 4-coumarate coenzyme A ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI). On 1 d and 2 d post-treatment, the activity of 4CL was respectively 3.78 and 6.1 times of the control, and on 5 d, the activity of PAL was increased by 4.47 times the control. The treatment of antagonistic bacteria delayed the peaking of cinnamyl-alcohol dehydrogenase (CAD) activity and promoted the accumulation of lignin and total phenols. The antagonistic bacteria could be well colonized in the wounds. On 4-5 d post-inoculation, the count of colonies was $10^8$ times of that upon inoculation. Electronmicroscopy indicated that the antagonistic bacteria delayed the germination of pathogenic spores in the wounds, and inhibited further elongations of the mycelia.

• The Plant Pathology Journal
• /
• 제18권2호
• /
• pp.57-62
• /
• 2002

In vivo expression technology (IVET) has been developed to study bacterial gene expression in Salmonella typhimurium during host infection. The expression of selected genes by IVET has been elevated in vivo but not in vitro. The selected genes turned out to be important for bacterial virulence and/or pathogenicity. IVET depends on a synthetic operon with a promoterless transcriptional fusion between a selection marker gene and a reporter gene. The IVET approach has been successfully adapted in other bacterial pathogens and plant-associated bacteria using different selection markers. Pseudomonas putida suppresses citrus root rot caused by Phytophthora parasitica and enhances citrus seedling growth. The WET strategy was adapted based on a transcriptional fusion, pyrBC'-lacZ, in P. putida to study the bacterial traits important far biocontrol activities. Several genes appeared to be induced on P. parasitica hyphae and were found to be related with metabolism and regulation of gene expression. It is likely that the biocontrol strain took a metabolic advantage from the plant pathogenic fungus and then suppressed citrus root rot effectively. The result was parallel with those from the adaptation of IVET in P. fluorescens, a plant growth promoting rhizobacteria (PGPR). Interestingly, genes encoding components for type III secretion system have been identified as rhizosphere-induced genes in the PGPR strain. The type III secretion system may play a certain role during interaction with its counterpart plants. Application of IVET has been demonstrated in a wide range of bacteria. It is an important strategy to genetically understand complicated bacterial traits in the environment.

• Journal of the Korean Wood Science and Technology
• /
• 제38권4호
• /
• pp.341-348
• /
• 2010

목초액의 농약 또는 식품보존제로서의 이용 가능성을 검토하기 위하여 소나무 및 참나무류 기계식 목초액을 대상으로 항진균 및 항세균 활성을 검정하였다. 그 결과 항진균활성의 경우 미정제 목초액은 0.5% 이상의 농도 에서, 정제 목초액은 1.0% 이상의 농도에서 공시 식물병원균 및 목재부후균의 생장을 완전히 억제하여 미정제 목초액이 정제 목초액보다 항균활성이 높은 것으로 나타났다. 그리고 참나무류 목초액이 소나무 목초액보다 항 균활성이 높아 탄화 원료인 수종에 따라 항균활성의 차이가 있음을 알 수 있었다. 균종별로는 표고 해균인 주홍 꼬리버섯에 대한 항균효과가 다른 공시 균주에 비해 높은 것으로 나타나 균의 종류에 따라 목초액에 대한 감수성이 차이가 있는 것으로 밝혀졌다. 한편, 식품부패균 및 식중독균에 대한 항세균활성을 검정한 결과 소나무 및 참나무류 미정제 목초액의 경우 10% 농도에서 모든 공시 균주에 대해 생육저지환을 형성한 반면 정제 목초액 의 경우에는 저지환을 형성하지 않아 항세균활성도 미정제액이 정제액보다 높은 것으로 나타났다. 균종에 따른 감수성에도 차이가 있어 그람 양성균에 대한 항균활성이 그람 음성균에 비해 상대적으로 높았으나 탄화 원료에 의한 차이는 뚜렷하게 나타나지 않았다. 이상의 결과 목초액은 식물병원균, 목재부후균, 식품부패균 및 식중독 균에 대한 항균활성이 우수하여 유기합성 농약을 대체하거나 식품의 부패를 막기 위한 식품보존제로서 이용이 가능할 것으로 판단되었다.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2004년도 The 2004 KSPP Annual Meeting & International Symposium
• /
• pp.65-67
• /
• 2004

During initial interactions of bacteria with their host plants, most plants recognize the bacterial infections and repel the pathogen by plant defense mechanism. The most active plant defense mechanism is the hypersensitive response (HR) which is the localized induced cell death in the plant at the site of infection by a pathogen. A primary locus induced in gram-negative phytopathogenic bacteria during this initial interaction is the Hrp locus. The Hrp locus is composed of a cluster of genes that encodes the bacteral Type 111 machinery that is involved in the secretion and translocation of effector proteins to the plant cell. DNA sequence analysis of hrp gene in phytopathogenic bacteria has revealed a Hrp pathogenicity is]and (PAI) with a tripartite mosaic structure. For many gram-negative pathogenic bacteria, colonization of the host's tissue depends on the type III protein secretion system (TTSS) which secrets and translocates effector proteins into the host cell. Effectors can be divided into several groups including broad host range effectors, host specific effectors, disease specific effectors, and effectors inhibit host defenses. The role of effectors carrying LRR domain in plant resistance is very elusive since most known plant resistance gene carry LRR domain. Host specific effectors such as several avr gene products are involved in the determination of the host specificity. Almost all the phytopathogenic Xanthomonas spp. carry avrBs1, avrBs2, and avrBs3 homologs. Some strains of X. oryzae pv. oryzae carry more than 10 copies of avrBs3 homologs. However, the functions of all those avr genes in host specificity are not characterized well.;