• 제목/요약/키워드: Resistant screening

검색결과 332건 처리시간 0.029초

Screening of Radio-resistant Lactic Acid Bacteria

  • Hwang, E-Nam;Kang, Sang-Mo;Kim, Jae-Kyung;Lee, Ju-Woon;Park, Jong-Heum
    • 한국축산식품학회지
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    • 제33권3호
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    • pp.335-340
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    • 2013
  • This study screened for radio-resistant strains lactic acid bacteria (LAB) by evaluating their capability to survive exposure to ionizing radiation. Ten strains of LAB - Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus delbruekii, Lactococcus lactis, Streptococcus thermophilus, Bifidobacterium breve, and Pediocuccos pentosaceus - were selected and subcultuted twice. The LAB was then further cultured for 3 d at $37^{\circ}C$ to reach 7-10 Log colony-forming units (CFU)/mL prior to irradiation and immediately exposed to gamma rays or electron beams with absorbed doses of 0, 1, 2, 3, 4, 5, 6, 8, and 10 kGy. Gamma irradiation gradually decreased the number of the tested viable LAB, and the effect was irradiation dose dependent. A similar effect was found in electron beam-irradiated LAB. Radiation sensitivity of LAB was calculated as $D_{10}$ values, which ranged from 0.26 kGy to 0.9 kGy and 0.5 kGy to 1.44 kGy with exposure to gamma and electron beam irradiation, respectively, in all tested LAB. L. acidophilus was the most resistant to gamma and electron beam irradiation, with $D_{10}$ values of 0.9 kGy and 1.44 kGy, respectively. These results suggest that L. acidophilus might be suitable for the preparation of probiotics as direct-fed microbes for astronauts in extreme space environments.

Pathotype Classification of Plasmodiophora brassicae Isolates Using Clubroot-Resistant Cultivars of Chinese Cabbage

  • Kim, Hun;Jo, Eun Ju;Choi, Yong Ho;Jang, Kyoung Soo;Choi, Gyung Ja
    • The Plant Pathology Journal
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    • 제32권5호
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    • pp.423-430
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    • 2016
  • Clubroot disease caused by Plasmodiophora brassicae is one of the most serious diseases in Brassica crops worldwide. In this study, the pathotypes of 12 Korean P. brassicae field isolates were determined using various Chinese cabbage including 22 commercial cultivars from Korea, China, and Japan, and 15 inbred lines. All P. brassicae isolates exhibited the typical clubroot disease on non-clubroot resistant cultivar, indicating that the isolates were highly pathogenic. According to the reactions on the Williams' hosts, the 12 field isolates were initially classified into five races. However, when these isolates were inoculated onto clubroot-resistant (CR) cultivars of Chinese cabbage, several isolates led to different disease responses even though the isolates have been assigned to the same race by the Williams' host responses. Based on the pathogenicity results, the 12 field isolates were reclassified into four different groups: pathotype 1 (GN1, GN2, GS, JS, and HS), 2 (DJ and KS), 3 (HN1, PC, and YC), and 4 (HN2 and SS). In addition, the CR cultivars from Korea, China, and Japan exhibited distinguishable disease responses to the P. brassicae isolates, suggesting that the 22 cultivars used in this study, including the non-CR cultivars, are classified into four different host groups based on their disease resistance. Combining these findings, the four differential hosts of Chinese cabbage and four pathotype groups of P. brassicae might provide an efficient screening system for resistant cultivars and a new foundation of breeding strategies for CR Chinese cabbage.

Paraquat-resistant lines in Pisum sativum cv. Alaska: biochemical and phenotypic characterization

  • Haque, Md. Emdadul;Yoshida, Yusuke;Hasunuma, Kohji
    • Plant Biotechnology Reports
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    • 제2권1호
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    • pp.21-31
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    • 2008
  • In plants, the oxygen generated by photosynthesis can be excited to form reactive oxygen species (ROS) under excessive sunlight. Excess ROS including singlet oxygen ($^1O_2$) inhibit the growth, development and photosynthesis of plants. To isolate ROS-resistant crop plants, we used paraquat (PQ), a generator of $O_2{^-}$ as a source of screening and mutagen, and obtained two PQ-resistant lines in Pisum sativum, namely R3-1 and R3-2. Both lines showed greater resistance to PQ than their wild type (WT) siblings with respect to germination, root growth, and shoot growth. Biochemical analysis showed differences in these lines, in which ROS-scavenging enzymes undergo changes with a distinguishable increase in Mn-SOD. We further observed that the cytosolic catalases (CATs) in leaves in both lines were shifted in a native-PAGE analysis compared with that of the WT, indicating that the release of bound $^1O_2$ was enhanced. Phenotypic analysis revealed distinguishable differences in leaf development, and in flowering time and position. In addition, R3-1 and R3-2 showed shorter individual inter-node lengths, dwarf plant height, and stronger branching compared with the WT. These results suggested that PQ-induced ROS-resistant Pisum have the potential pleiotropic effects on flowering time and stem branching, and that ROS including $^1O_2$ plays not only important roles in plant growth and development as a signal transducer, but also appears as a strong inhibitor for crop yield.

A Rapid and Efficient Screening Method for Antibacterial Compound-Producing Bacteria

  • Hettiarachchi, Sachithra Amarin;Lee, Su-Jin;Lee, Youngdeuk;Kwon, Young-Kyung;Zoysa, Mahanama De;Moon, Song;Jo, Eunyoung;Kim, Taeho;Kang, Do-Hyung;Heo, Soo-Jin;Oh, Chulhong
    • Journal of Microbiology and Biotechnology
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    • 제27권8호
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    • pp.1441-1448
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    • 2017
  • Antibacterial compounds are widely used in the treatment of human and animal diseases. The overuse of antibiotics has led to a rapid rise in the prevalence of drug-resistant bacteria, making the development of new antibacterial compounds essential. This study focused on developing a fast and easy method for identifying marine bacteria that produce antibiotic compounds. Eight randomly selected marine target bacterial species (Agrococcus terreus, Bacillus algicola, Mesoflavibacter zeaxanthinifaciens, Pseudoalteromonas flavipulchra, P. peptidolytica, P. piscicida, P. rubra, and Zunongwangia atlantica) were tested for production of antibacterial compounds against four strains of test bacteria (B. cereus, B. subtilis, Halomonas smyrnensis, and Vibrio alginolyticus). Colony picking was used as the primary screening method. Clear zones were observed around colonies of P. flavipulchra, P. peptidolytica, P. piscicida, and P. rubra tested against B. cereus, B. subtilis, and H. smyrnensis. The efficiency of colony scraping and broth culture methods for antimicrobial compound extraction was also compared using a disk diffusion assay. P. peptidolytica, P. piscicida, and P. rubra showed antagonistic activity against H. smyrnensis, B. cereus, and B. subtilis, respectively, only in the colony scraping method. Our results show that colony picking and colony scraping are effective, quick, and easy methods of screening for antibacterial compound-producing bacteria.

종자접종법에 의한 대두 자반병 저항성 검정에 관한 연구 (Screening for Resistance to Purple Seed Stain 'Cercospora kikuchii' by Seed Inoculation Technique.)

  • 권신한;오정행
    • 한국작물학회지
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    • 제23권2호
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    • pp.113-117
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    • 1978
  • 대두 자반병에 대하여 저항성인 계통 선발을 위한 Mass-screening technique를 확립하고 이 종자잡종법을 이용하여 수집재내종 및 각 품종의 저항성검정을 실시한 결과는 다음과 같다. 1. 조숙성인 수집재내종 50계통의 자반병 자연감염률과 종자접종에 의한 자주빛 색소 형성률간에 나타난 정의 상관관계는 r=0.121로서 고도의 유의성이 인정되었으며 이 종자접종법은 효과약인 Mass-screening technique으로서 방사선을 이용한 돌연변이육종에서 자반병저항성 계통선발에 이용가능성이 높았다. 2. 자반병 자연감염률이 극히 낮은 만숙성 수집재내종 85계통은 종자접종에 의하여 대부분이 이병성 반응을 보였으며 이는 포장에서의 만숙계통의 저항성이 유전적인 특성이기 보다는 병해도피 현상에 기인한 것으로 생각되었다. 3. 대두품종의 저항성검정에서 우리나라 대두 36품종을 비롯하여 일본과 대만의 각 16품종, 베트남 11품종, 필리핀 8품종 및 미국 38품종 등 대부분이 이병성이였고 미국품종인 Sac, Hill, Harosoy등이 비교적 저항성 이었다. 4. 각 지역에서 분리한 대두 자반병균 244 isolates 중에서 배지에서 자주빛 색소를 형성하지 않는 두 균주를 제외하고는 모두가 암조건에서는 감자한천배지에서, 광조건에서는 오트밀한친배지에서 자주빛 색소형성이 잘 되었으며 배지에서의 색소형성 정도는 종자에서의 병원성과 밀접한 상관이 있었다.

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우리나라 벼 도열병균의 대표 균주 및 벼의 저항성 유전자형 선발 (Selection of Representative Magnaporthe oryzae Isolates and Rice Resistant Gene Types for Screening of Blast-resistant Rice Cultivars)

  • 고재덕;김병련;이세원;노재환;신동범;정지웅;조영찬;한성숙
    • 식물병연구
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    • 제19권4호
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    • pp.243-253
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    • 2013
  • 벼 도열병은 안정적인 쌀 생산을 위협하는 대표적인 병으로, 도열병 방제에는 저항성 품종의 육종이 가장 효과적으로 이용되었다. 병원균의 꾸준한 수집과 이들을 이용한 저항성 검정 테스트는 신품종 육성 프로그램에서 중요한 과정이다. 1985년 이래 우리나라의 도열병균은 8개의 판별품종을 이용한 레이스 판별시스템을 구축하여 분류하였다. 그러나 기존의 판별품종은 유전자형이 연구된 바 없어 새로운 레이스 출현이나 병 저항성 붕괴 등에 대하여 과학적으로 분석하여 신속하게 대처하기가 어려웠다. 따라서 이 연구에서는 유전자형이 밝혀진 단인자 저항성 계통과 우리나라에서 수집된 200개 균주의 병원성 반응을 분석하여, 새로운 판별 품종 시스템의 필요성을 제시하였다. 또한, 24개의 단인자 저항성 계통의 병원성 반응을 통해 9개의 대표 저항성 유전자를 선발하였으며, 이에 따른 10개의 대표균주 그룹과 그 저항성 반응을 인덱스화 하고 30개의 한국형 대표균주를 선발하였다. 이 연구는 향후 도열병 저항성 검정 및 벼 신품종 육종에 기초자료로서 활용될 수 있을 것이다.

Field Evaluation of Mungbean Recombinant Inbred Lines against Mungbean Yellow Mosaic Disease Using New Disease Scale in Thailand

  • Akhtar, Khalid P.;Kitsanachandee, R.;Srinives, P.;Abbas, G.;Asghar, M.J.;Shah, T.M.;Atta, B.M.;Chatchawankanphanich, O.;Sarwar, G.;Ahmad, M.;Sarwar, N.
    • The Plant Pathology Journal
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    • 제25권4호
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    • pp.422-428
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    • 2009
  • Studies were conducted to identify the sources of resistance in mungbean recombinant inbred lines (RILs) in Thailand against mungbean yellow mosaic disease (MYMD). 146 mungbean RILs in $F_8$ series were evaluated in a field including resistant parent NM-10-12-1 and susceptible parent KPS 2 during summer 2008 under high inoculum pressure. The RILs were subsequently scored for disease symptom severity ratings (DSSR) using a new scale. Observations regarding DSSR and % disease index (%DI) showed that the tested RILs responded differently to the disease. A large number of RILs (132) were found highly susceptible, 12 were susceptible, 3 were tolerant and one was resistant. Overall screening results showed that three RILs, viz. line no. 30, 100 and 101 had minimum DSSR and % disease index thus they are good source of resistance to MYMD in spite of high disease pressure and can therefore be used directly as varieties to manage the disease in Thailand.

Screening and Characterization of Pro biotic Lactic Acid Bacteria Isolated from Korean Fermented Foods

  • Lim, Sung-Mee;Im, Dong-Soon
    • Journal of Microbiology and Biotechnology
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    • 제19권2호
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    • pp.178-186
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    • 2009
  • To examine their potential as probiotics, acid and bile tolerance, antibiotics resistance, adhesion capacity to Caco-2 and HT-29, and antibacterial activity, of LAB isolated from Korean fermented foods such. as dongchimi, kimchi, Meju, and doenjang were assayed against foodborne pathogenic bacteria. DC 55, DC 136, DC 222, KC 21, KC 24, KC 34, KC 43, KC 117, MJ 54, MJ 301, SP 33, and SP 170 strains were resistant to acid and bile conditions. In particular, DC 55, DC 136, KC 24, KC 43, and MJ 301 strains were highly resistant to higher than 20 ${\mu}g/ml$ concentrations of vancomycin, streptomycin sulfate, or amoxicillin, whereas, DC 222, KC 21, KC 34, KC 117, MJ 54, and SP 33 strains were susceptible to lower than 2 ${\mu}g/ml$ concentrations of those antibiotics. The adhesion to HT-29 and Caco-2 cells varied with the strains tested in a strain-dependent manner. The highest level of adhesion was observed with DC 55, KC 21, KC 24, and MJ 301 strains, having higher than 50% of adhesion to HT-29 or Caco-2 cells. In addition, Staphylococcus aureus was the most sensitive to KC 21, showing an inhibition of about 70%, and the antibacterial activity of KC 21 against S. aureus resulted most likely from both organic acids and bacteriocin. Based on its phenotypic characteristics and utilization of various sugars, the KC 21 strain was identified as Lactobacillus plantarum.

Mithramycin Inhibits Etoposide Resistance in Glucose-deprived HT-29 Human Colon Carcinoma Cells

  • Lee, Eun-Mi;Park, Hae-Ryong;Hwang, Ji-Hwan;Park, Dong-Jin;Chang, Kyu-Seob;Kim, Chang-Jin
    • Journal of Microbiology and Biotechnology
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    • 제17권11호
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    • pp.1856-1861
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    • 2007
  • Physiological cell conditions such as glucose deprivation and hypoxia play roles in the development of drug resistance in solid tumors. These tumor-specific conditions cause decreased expression of DNA topoisomerase $II{\alpha}$, rendering cells resistant to topo II target drugs such as etoposide. Thus, targeting tumor-specific conditions such as a low glucose environment may be a novel strategy in the development of anticancer drugs. On this basis, we established a novel screening program for anticancer agents with preferential cytotoxic activity in cancer cells under glucose-deprived conditions. We recently isolated an active compound, AA-98, from Streptomyces sp. AA030098 that can prevent stress-induced etoposide resistance in vitro. Furthermore, LC-MS and various NMR spectroscopic methods identified AA-98 as mithramycin, which belongs to the aureolic acid group of antitumor compounds. We found that mithramycin prevents the etoposide resistance that is induced by glucose deprivation. The etoposide-chemosensitive action of mithramycin was just dependent on strict low glucose conditions, and resulted in the selective cell death of etoposide-resistant HT-29 human colon cancer cells.

Description of 17 unrecorded bacterial species isolated from freshwater showing antibiotic resistance in Korea

  • Baek, Kiwoon;Kim, Eui-Jin;Han, Ji-Hye;Choi, Ahyoung
    • 환경생물
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    • 제38권2호
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    • pp.289-298
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    • 2020
  • As part of the research program "2018 Rapid screening and identification of freshwater microorganisms using MALDI-TOF/MS library" freshwater samples were collected from a branch of the Nakdong River. Almost 300 antibiotic-resistant bacterial strains were isolated from freshwater samples and subsequently identified by 16S rRNA gene sequencing. Seventeen strains among the isolates shared high 16S rRNA gene sequence similarity (>99.0%) with known species that were not previously recorded in Korea, and each of the isolates also formed a robust phylogenetic clade with the closest species. These species were phylogenetically diverse, belonging to four phyla, seven classes, 10 orders, and 13 genera. At the genus and class level, the previously unrecorded species belonged to Rhodovarius, Xanthobacter, and Shinella of the class Alphaproteobacteria; Ottowia, Simplicispira, and Zoogloea of Betaproteobacteria; Pseudomonas, Acinetobacter, and Shewanella of Gammaproteobacteria; Arcobacter of Epsilonproteobacteria; Sphingobacterium of Sphingobacteriia; Trichococcus of Bacilli; and Leucobacter of Actinobacteria. The previously unrecorded species were further characterized by examining their gram-staining, colony and cell morphology, biochemical properties, and phylogenetic position.