• 식물병연구
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• 제24권1호
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• pp.59-65
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• 2018

Pyraclostrobin은 광범위한 스펙트럼의 항진균 활성이 있는 퀴논외부저해제(Quinone outside inhibitor, QoI)로 작용하는 살균제이다. 기존 보고에 의하면 pyraclostrobin이 일부 세균병과 바이러스병에 대해 병 저항성을 유도한다고 알려져 있다. 본 연구는 pyraclostrobin 항진균제를 활용하여 고추 세균점무늬병(Xanthomonas euvesicatoria)의 예방 가능성을 검토하였다. Pyraclostrobin은 in vitro 상에서 X. euvesicatoria에 대해 항균활성이 없었지만, 고추에 pyraclostrobin 단독(방제가 69%) 또는 streptomycin과 혼합 살포(방제가 90%) 하였을 때, 고추 세균점무늬병 예방 효과를 나타냈다. Pyraclostrobin의 고추 세균점무늬병 예방 효과는 병원균 접종 1-3일전이 효과적이었다. 이상의 결과로 pyraclostrobin 살진균제를 활용하여 고추 세균점무늬병을 효과적으로 예방할 수 있을 것을 사료된다.

• Toxicological Research
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• 제20권1호
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• pp.43-47
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• 2004

In order to investigate the safety of a water extract (ADP) of 1 : 1 mixture of Anemarrhena rhizoma and Phellodendron cortex for alleviating benign prostate hyperplasia, genotoxicity studies in bacterial and mammalian cell assay systems, namely, the Ames bacterial reverse mutation and chromosomal aberration assays were performed. As shown by the results of the Ames bacterial reversion assay, ADP in the range of 625-5000 $\mu\textrm{g}$/plate did not induce mutagenicity in Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 strains in the absence or in the presence of S9 (the microsomal fraction of rat liver homogenate) metabolic activation. The $IC_{50}$ (50% cell growth inhibition concentration) values of ADP for the chromosomal aberration assay were determined; these were 2425 $\mu\textrm{g}$/ml in the absence and 8126 $\mu\textrm{g}$/ml in the presence of S9 metabolic activation in Chinese hamster lung (CHL) fibroblast cell culture. No chromosomal aberration was observed in CHL cells treated with ADP at 2425, 1212.5 and 606.25 $\mu\textrm{g}$/ml in the absence, or at 8126, 4063 and 2031.5 $\mu\textrm{g}$/ml in the presence of S9 metabolic activation. These results show that under the conditions used, ADP does not harmfully affect the bacterial or mammalian cell system at the gene level.

• Asian-Australasian Journal of Animal Sciences
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• 제28권4호
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• pp.584-591
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• 2015

This study characterized the fecal bacterial community structure and inter-individual variation in 30-week-old Duroc pigs, which are known for their excellent meat quality. Pyrosequencing of the V1-V3 hypervariable regions of the 16S rRNA genes generated 108,254 valid reads and 508 operational taxonomic units at a 95% identity cut-off (genus level). Bacterial diversity and species richness as measured by the Shannon diversity index were significantly greater than those reported previously using denaturation gradient gel electrophoresis; thus, this study provides substantial information related to both known bacteria and the untapped portion of unclassified bacteria in the population. The bacterial composition of Duroc pig fecal samples was investigated at the phylum, class, family, and genus levels. Firmicutes and Bacteroidetes predominated at the phylum level, while Clostridia and Bacteroidia were most abundant at the class level. This study also detected prominent inter-individual variation starting at the family level. Among the core microbiome, which was observed at the genus level, Prevotella was consistently dominant, as well as a bacterial phylotype related to Oscillibacter valericigenes, a valerate producer. This study found high bacterial diversity and compositional variation among individuals of the same breed line, as well as high abundance of unclassified bacterial phylotypes that may have important functions in the growth performance of Duroc pigs.

• Mycobiology
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• 제34권2호
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• pp.67-72
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• 2006

Efficacy of resistance induction by the bacterial isolates Pseudomonas putida (TRL2-3), Micrococcus luteus (TRK2-2) and Flexibacteraceae bacterium (MRL412), which were isolated from the rhizosphere of plants growing in Jeju Mountain, were tested in a greenhouse. The disease severity caused by Phytophthora infestans was effectively reduced in the potato plants pre-inoculated with bacterial isolates compared with those of the untreated control plants growing in a greenhouse. In order to estimate the level of protection by the bacterial isolates, Mancozeb WP (Diesen $M^{(R)}$, Kyong nong) and DL-3-amino butyric acid (BABA) were pre-treated, whereas Dimethomorph WP ($Forum^{(R)}$, Kyong nong) and phosphonic acid ($H_{3}PO_{3}$) were post-treated the challenge inoculation with the pathogen. Disease severities of chemical pre-treated as well as post-treated plants were reduced compare to those of the untreated. The disease reduction in the plants pre-treated with Mancozeb WP was the highest, whereas that of post-treated with Dimethomorph WP was the lowest. The yields of plants pre-inoculated with three bacterial isolates were greatly increased than those of control plants. These results suggest that biological control by bacterial isolates might be an alternative strategy against late blight disease in potato plants growing in greenhouse.

• 한국미생물·생명공학회지
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• 제46권4호
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• pp.346-359
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• 2018

Xanthomonas oryzae, a bacterial pathogen causing leaf blight disease (BLB) in rice, can cause widespread disease and has caused epidemics globally, resulting in severe crop losses of 50% in Asia. The pathogen is seed-borne and is transmitted through seeds. Thus, control of BLB requires the elimination of the pathogen from seeds. Concern about environment-friendly organic production has spurred improvements in a variety of biological disease control methods, including the use of bacteriophages, against bacterial plant pathogens. The present study explored the potential of bacteriophages isolated from diseased plant leaves and soil samples in killing the bacterial pathogen in rice seeds. Eight different phages were isolated and evaluated for their bacteriolytic activity against different pathogenic X. oryzae strains. Of these, a phage designated ${\varphi}XOF4$ killed all the pathogenic X. oryzae strains and showed the broadest host range. Transmission electron microscopy of ${\varphi}XOF4$ revealed it to be a tailed phage with an icosahedral head. The virus was assigned to the family Siphoviridae, order Caudovirales. Seedlings raised from the seeds treated with $1{\times}10^8pfu/ml$ of ${\varphi}XOF4$ phage displayed reduced incidence of BLB disease and complete bacterial growth inhibition. The findings indicate the potential of the ${\varphi}XOF4$ phage as a potential biological control agent against BLB disease in rice.

• 한국작물학회지
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• 제26권1호
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• pp.40-44
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• 1981

답잡초 돌피 외 19종을 대상으로 병원균군, 접종방법 및 잡율의 생육시기를 달리하여 벼흰빛잎마름병의 기주범국 구명시험에서 얻어진 결과를 요약하면 다음과 같다. 1. 나도겨풀, 강아지풀, 독새풀 등은 밀양 2003에 준한 이병성을 나타냈으며, 그 밖에 바랭이, 왕바램이 알방동산이, 너도방동산이, 바람하늘지기 등에서 이병성을 보였으나 광엽잡초에는 전혀 이병되지 않았다. 2. 생육초기에 이병성을 크게 보인 강아지풀, 나도겨풀, 독새풀은 생육전기간을 통해서 이병성이 컸으며, 균군간에는 제일군이 병원성이 다소 큰 것 같았다. 3. 접종방법별로는 유상접종인 핀 및 가위 접종이 무상접종의 분무접종보다 이병성이 켰다.

• 식물병연구
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• 제26권3호
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• pp.159-169
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• 2020

Pactobacterium carotovorum subsp. carotovorum (Pcc)에 의한 무름병은 전세계적으로 문제가 되고 있고 특히 온난 다습한 지역에서 문제가 심각하다. 본 연구는 Pcc에 의해 발생하는 배추 무름병에 대한 효율적인 저항성 검정법을 확립하기 위하여 실험하였다. 시판 배추 품종 65개의 Pcc KACC 10225에 대한 저항성 정도를 조사하고, 추후 실험을 위해 저항성에 차이를 보이는 3개 품종을 선발하였다. 이들 3개 품종의 접종하는 배추의 생육 시기, 접종원 농도, 접종 후 재배 온도 등의 발병 조건에 따른 무름병 발생을 조사하였다. 이들 실험의 결과로부터 배추의 무름병에 대한 저항성을 검정하기 위해서는, 배추 종자를 파종하고 온실(25±5℃)에서 21일 동안 재배한 유묘에 Pcc 균주의 세균현탁액(1×10⁷ cfu/ml)을 식물체 기부에 5 ml씩 관주하여 접종하고, 접종한 식물은 25℃ 습실상에 24시간 동안 배양한 후에 25℃, 상대습도 80%의 생육상으로 이동하여 재배하는 것을 제안하고자 한다.

• 한국축산식품학회지
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• 제26권3호
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• 한국환경농학회지
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• 제40권1호
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• pp.49-59
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• 2021

BACKGROUND: Soil salinity causes reduction of crop productivity. Rhizosphere microbes have metabolic capabilities and ability to adaptation of plants to biotic and abiotic stresses. Plant growth-promoting bacteria (PGPB) could play a role as elicitors for inducing tolerance to stresses in plants by affecting resident microorganism in soil. This study was conducted to demonstrate the effect of selected strains on rhizosphere microbial community under salinity stress. METHODS AND RESULTS: The experiments were conducted in tomato plants in pots containing field soil. Bacterial suspension was inoculated into three-week-old tomato plants, one week after inoculation, and -1,000 kPa-balanced salinity stress was imposed. The physiological and biochemical attributes of plant under salt stress were monitored by evaluating pigment, malondialdehyde (MDA), proline, soil pH, electrical conductivity (EC) and ion concentrations. To demonstrate the effect of selected Bacillus strains on rhizosphere microbial community, soil microbial diversity and abundance were evaluated with Illumina MiSeq sequencing, and primer sets of 341F/805R and ITS3/ITS4 were used for bacterial and fungal communities, respectively. As a result, when the bacterial strains were inoculated and then salinity stress was imposed, the inoculation decreases the stress susceptibility including reduction in lipid peroxidation, enhanced pigmentation and proline accumulation which subsequently resulted in better plant growth. However, bacterial inoculations did not affect diversity (observed OTUs, ACE, Chao1 and Shannon) and structure (principle coordinate analysis) of microbial communities under salinity stress. Furthermore, relative abundance in microbial communities had no significant difference between bacterial treated- and untreated-soils under salinity stress. CONCLUSION: Inoculation of Bacillus strains could affect plant responses and soil pH of tomato plants under salinity stress, whereas microbial diversity and abundance had no significant difference by the bacterial treatments. These findings demonstrated that Bacillus strains could alleviate plant's salinity damages by regulating pigments, proline, and MDA contents without significant changes of microbial community in tomato plants, and can be used as effective biostimulators against salinity stress for sustainable agriculture.

• Mycobiology
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• 제42권2호
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• pp.158-166
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• 2014

In this study, bacterial strains were isolated from soils from 30 locations of Samcheok, Gangwon province. Of the isolated strains, seven showed potential plant growth promoting and antagonistic activities. Based on cultural and morphological characterization, and 16S rRNA gene sequencing, these strains were identified as Paenibacillus species. All seven strains produced ammonia, cellulase, hydrocyanic acid, indole-3-acetic acid, protease, phosphatase, and siderophores. They also inhibited the mycelial growth of Fusarium oxysporum f. sp. radicis-lycopersici in vitro. The seven Paenibacillus strains enhanced a range of growth parameters in tomato plants under greenhouse conditions, in comparison with non-inoculated control plants. Notably, treatment of tomato plants with one identified strain, P. polymyxa SC09-21, resulted in 80.0% suppression of fusarium crown and root rot under greenhouse conditions. The plant growth promoting and antifungal activity of P. polymyxa SC09-21 identified in this study highlight its potential suitability as a bioinoculant.