• 대한미생물학회지
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• 제19권1호
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• pp.11-24
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• 1984

Shigella remains to be an important enteric pathogen in this country for the present. Moreover, most of the isolates have become multiple resistant to various antibiotics which used to be drugs of choice for shigellosis. This study was made as an attempt to assess the present stage of antibiotic resistance and the incidence and transferability of R factors of Shigella. A total of one hundred and seventeen strains of Shigella isolated from patients in Seoul and provincial area between 1982 and 1983 were tested for their resistant to antimicrobial agents and transmission of R-plasmid. Antibiotic susceptibilities were determined by an agar dilution method. Muller hinton agar were used for the assay of drug resistance and tryptic soy broth were used for propagating medium for conjugation. Shigella isolated found to be one or more antibiotics were considered potential donor of R-plasmid. The following results were obtained. 1. Among 117 strains of Shigella isolated, 111 strains(94.9%) were found to be resistant to one or more drugs tested and 97.3% of these resistant strains were multiply resistant, indicating the multiply resistant strains were more than the single resistant strains. Only six strains were susceptible to all drugs tested. 2. Among 117 strains of Shigella isolated, 107 strains(91.5%) were resistant to Tetracyclin(Tc), 106 strains(90.6%) to Chloramphenicol(Cp) and Streptomycin(Sm), 97 strains(82.9%) to Ampicillin(Ap), 68 strains(58.1%) to Cephaloridine(Cr), 10 strains(8.5%) to Nalidixic acid(Na), 5 strains(4.3%) to Kanamycin(Km) and 2 strains(1.7%) to Rifampicin. No strain was resisfant to Amikacin(Ak) and Gentamicin(Gm). 3. All drug-resistant Shigella strains, except three, were multiply resistant to two or more drugs. Fifty eight strains were resistant to five drugs, followed by 26 strains resistant to dour drugs, 12 strains resistant to three drugs and 11 strains resistant to six drugs. 4. The 73% of multiply drug-resistant Shigella transferred their resistance to E. coli by conjugation and the resistance was considered to be mediated by R-plasmid. Resistance to Nalidixic acid and Rifampicin were not transferred by conjugation to recipient. As for the transferability of resistance to each seperate drug, Ap resistance was transferred with 73.2% frequence and Cm and Tc resistance were transferred with approximately 50-60% frequence whereas Sm and Cr resistance were transferred in 19.1-21.4% The other four drugs resistant failed to transfer their resistance to recipient. 5. As for the incidence and transferability of resistance to each seperate drug, the strains resistant to Tc and Cm were encountered most frequently with the rate of 91-92%, whereas transfer of Tc and Cm were low, 51-52%. The incidence of Sm resistance was very high(90.6%) but transferability of drugs resistance was much lower(25.4%). Though the incidence of Km reristance was much lower(4.3%) transferability of Km resistance was considerably higher(60%). 6. The greater the multiplicity of resistance, the greater was the likelihood that part of all of the resistance markers would be transferable.

• Food Science and Biotechnology
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• 제17권1호
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• pp.195-198
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• 2008

This study was carried out to investigate the potential use of Zanthoxylum schinifolium and Zanthoxylum piperitum A.P. DC. as a source of antimicrobial agents against food borne pathogens. Essential oils of Z. schinifolium and Z. piperitum A.P. DC. were collected by steam distillation and analyzed by GC-MS. The antimicrobial activity of the essential oils was examined using the agar diffusion and micro-dilution assays. The effectiveness of Z. schinifolium essential oil was greater against Bacillus cereus, Staphylococcus aureus, and Vibrio parahaemolyticus than other pathogens, and the minimal inhibitory concentration (MIC) values were 1.25, 2.5, and 1.25, 2.5, and $1.25\;{\mu}g/mL$, respectively. Z. piperitum A.P. DC. essential oil was the most effective against all pathogens tested except for Escherichia coli O157:H7, and the MIC values against B. cereus, Salmonella choleraesuis, and V. parahaemolyticus were 1.25, 2.5, and $1.25\;{\mu}g/mL$, respectively. Limonene, the major component of Z. piperitum A.P. DC. essential oils, had the highest inhibitory activity toward V. parahaemolyticus with a MIC value of $0.15\;{\mu}g/mL$. Meanwhile, citronellal and geranyl acetate, major components of both essential oils, displayed antibacterial activity against only B. cereus with MIC values of 1.25 and $5\;{\mu}g/mL$, respectively. Therefore, these essential oils could be useful as antimicrobial agents against foodborne pathogens.

• Restorative Dentistry and Endodontics
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• 제38권1호
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• pp.36-42
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• 2013

Objectives: This study evaluated the antibacterial effect and mechanical properties of composite resins ($L_{CR}$, $M_{CR}$, $H_{CR}$) incorporating chitosan with three different molecular weights (L, Low; M, Medium; H, High). Materials and Methods: Streptococcus (S). mutans 100 mL and each chitosan powder were inoculated in sterilized 10 mL Brain-Heart Infusion (BHI) solution, and was centrifuged for 12 hr. Absorbance of the supernatent was measured at $OD_{660}$ to estimate the antibacterial activities of chitosan. After S. mutans was inoculated in the disc shaped chitosan-containing composite resins, the disc was cleansed with BHI and diluted with serial dilution method. S. mutans was spread on Mitis-salivarius bacitracin agar. After then, colony forming unit (CFU) was measured to verify the inhibitory effect on S. mutans biofilm. To ascertain the effect on the mechanical properties of composite resin, 3-point bending and Vickers hardness tests were done after 1 and 3 wk water storage, respectively. Using 2-way analysis of variance (ANOVA) and Scheffe test, statistical analysis was done with 95% significance level. Results: All chitosan powder showed inhibition effect against S. mutans. CFU number in chitosan-containing composite resins was smaller than that of control resin without chitosan. The chitosan containing composite resins did not show any significant difference in flexural strength and Vickers hardness in comparison with the control resin. However, the composite resin, $M_{CR}$ showed a slightly decreased flexural strength and the maximum load than those of control and the other composite resins $H_{CR}$ and $L_{CR}$. Conclusions: $L_{CR}$ and $H_{CR}$ would be recommended as a feasible antibacterial restorative due to its antibacterial nature and mechanical properties.

• 대한수의학회지
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• 제27권2호
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• pp.235-243
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• 1987

This paper deals with the distribution of Yersinia spp. isolated from the feces or the cecal contents of 1,755 pigs, 558 cows, 428 pigs slaughtered, 271 dogs slaughtered and 91 deer during the period of March 1985 to February 1986. Isolated Yersinia spp. were examined for serotype, biotype and antibiotic susceptibility of Y. enterocolitica. The results were as follows; One hundred and fourty-three stains of Yersinia spp. were isolated from 141(4.5%) out of 3,103 animals examined and their isolates were identified as Y. enterocolitica(138 strains), Y. kristensenii (3 strains), Y. intermedia(1 strain) and Y. pseudotuberculosis(1 strain). Yersinia spp. were isolated from 122(7.0%) of 1,755 pigs in piggeries, 15(3.5%) of 428 pigs slaughtered and 4(1.5%) of 271 dogs slaughtered, but no Yersinia spp. were isolated from cows and deer. The isolation rate of Yersinia spp. in pigs ranged from 5.9~8.0% in piggeries, it was higher in summer and autumn and highest in fattening pigs groups(10.4%), especially. One hundred and thirty-eight Y. enterocolitica isolates belonged to serotype 0 : 3(95 strains), 0 : 8(13 strains), 0 : 5(7 strains), 0 : 9(6 strains), 0 : 1, 2(1 strain) and untypable(16 strains), among them strains of serotype 0 : 3 biotype 3B(91 strains) were predominant. Antibiotic susceptibility test of 138 isolates of Yersinia spp. was performed by the agar dilution method, using 8 antibiotics as follows: ampicillin(Am), chloramphenicol, kanamycin, nalidixic acid(Na), rifampicin(Rf), streptomycin, sulfadimethoxine(Su) and tetracycline. All the strains tested were susceptible to Rf and Na, but resistant to Su, and 136 strains(98.6%) were also resistant to Am.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.825-833
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• 2017

Strain IMCC26207 was isolated from the surface layer of Lake Soyang in Korea by the dilutionto-extinction culturing method, using a liquid medium prepared with filtered and autoclaved lake water. The strain could neither be maintained in a synthetic medium other than natural freshwater medium nor grown on solid agar plates. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain IMCC26207 formed a distinct lineage in the order Acidimicrobiales of the phylum Actinobacteria. The closest relative among the previously identified bacterial taxa was "Candidatus Microthrix parvicella" with 16S rRNA gene sequence similarity of 91.7%. Here, the draft genome sequence of strain IMCC26207, a freshwater actinobacterium, is reported with the description of the genome properties and annotation summary. The draft genome consisted of 10 contigs with a total size of 3,316,799 bp and an average G+C content of 57.3%. The IMCC26207 genome was predicted to contain 2,975 protein-coding genes and 51 non-coding RNA genes, including 45 tRNA genes. Approximately 76.8% of the protein coding genes could be assigned with a specific function. Annotation of the IMCC26207 genome showed several traits of adaptation to living in oligotrophic freshwater environments, such as phosphorus-limited condition. Comparative genomic analysis revealed that the genome of strain IMCC26207 was distinct from that of "Candidatus Microthrix" strains; therefore, we propose the name "Candidatus Limnosphaera aquatica" for this bacterium.

• 한국식물병리학회지
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• 제1권1호
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• pp.33-37
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• 1985

황록색줄무늬모자익과 줄기 정단부가 구부러지는 증상을 보이는 대두 이병주를 채집하여 지표식물검정, 충매전염, 물리적 성질 조사, 항혈청검정 및 전자현미경검경을 하였다. 지표식물검정결과 T. expansa와 Scotia에 국부병반반응, 동부, 완두, 명아주 등에 전신감염 증상을 일으켰다. 복숭아혹진딧물에 의한 전염율은 $90\%$였다. 물리적 성질은 내열성이 $60^{\circ}C$, 내희석성이 1,000배였고, 내보존성이 2일이었다. 바이러스를 순화하여 항혈청제조결과 1:1024의 역가를 보였으며 일본 바이러스연구소에서 분양 받고 AMV 항혈청과 양성반응을 보였다. 전자현미경검경 결과 대부분 길이가 60nm인 박테리아 모양의 바이러스 입자가 검경되었다.

• 한국작물학회지
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• 제45권2호
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• pp.143-149
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• 2000

From the soils of soybean fields in Cotton Branch Station (CBS) and Pine Tree Station (PTS), Arkansas, USA, various single spore isloates of sudden death syndrome (SDS) pathogen were obtained on modified Nash ＆ Snyder's medium (MNSM) with dilution plating technique and transferred to potato dextrose agar (PDA) medium to identify the cultural colony shape. The colony shapes of these isolates resembled F. solani isolate 171 which was white and chalky shaped on MNSM and most of them had unique form of morphology which produced white margin and blue center colony on PDA. Although, some of these isolates had more dark blue or showed slightly different color, all isolates that were selected randomly for green-house inoculation assay produced typical foliar symptoms on leaves of soybean, Hartz 6686. To determine the genetic differences among the isolates, mitochondrial DNA restriction fragment length polymorphism (RFLP) was conducted with fourty isolates from both fields, using mtDNA probes, 2U18 and 4U40, derived from Colletotrichum orbiculare. We obtained distinctive RFLPs in each treatment of restriction enzyme, EcoRI and HaeⅢ. Isolates, 11-2-5 and 14-3-1-1, from CBS and isolates, 104-3-1-2 and 701-1-5-1, from PTS showed different band patterns from 171 in both or in either treatment of restriction enzymes. Even if some of these isolates showed heterogeneous, they were more closer to 171 than PN603. And, also, rest of the thirty-six isolates had exactly same polymorphisms as 171 in each treatment of restriction enzyme. Although, some of the isolates showed the different morphological shape on PDA and slightly different band patterns on RFLPs, all of the isolates selected on MNSM due to their distinctive colony shape from other fungi produced the typical foliar symptoms on soybean leaves in greenhouse inoculation assay. It might be suggested that these isolates were not genetically different from check isolate 171 and they were unique strain of F. solani.

• 한국식품과학회지
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• 제49권2호
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• pp.146-150
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• 2017

본 연구에서는 지금까지 거의 보고된 바 없는 corosolic acid의 항균활성에 대해 대표적 식중독균 중 하나인 S. aureus를 대상으로 연구하였다. 대수기의 S. aureus에 corosolic acid를 처리하여 생장 저해 여부를 확인하였고, broth micro-dilution 방법과 agar disc diffusion 방법을 통해 corosolic acid의 S. aureus에 대한 항균활성을 측정해본 결과, corosolic acid의 농도에 비례하여 S. aureus 생장이 저해되는 것으로 확인되었다. 또한 corosolic acid의 존재 조건에서 S. aureus의 바이오필름 형성능이 MIC 보다 높은 농도뿐 아니라 낮은 농도에서 역시 저해되는 것으로 관찰되었다. 따라서 천연물질인 corosolic acid는 S. aureus에 의한 식품 오염을 억제하고 식중독 예방 및 잠재적 치료제로서 개발 될 가능성이 있는 것으로 판단되며, 나아가 다른 종류의 식중독균들에 대한 적용 가능 연구가 필요할 것으로 사료된다.

• 대한미생물학회지
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• 제15권1호
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• pp.33-38
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• 1980

Shigella remains to be an important enteric pathogen in this country for the moment. Moreover, since 1978, most of the isolates have become resistant to ampicillin and co-trimoxazole, which used to be the drugs of choice for shigellosis. Since a disc diffusion technique alone has been used in our routine susceptibility test, the minimum inhibitory concentrations(MIC) of both ampicillin and co-trimoxazole to Shigella have never been known. In order to determine these, 195 isolates were tested by an agar dilution method, all of which were isolated at Yonsei Medical Center during the period of June 1978 to July 1980. The following results were obtained. 1. Sixty cultures(29.7%) were susceptible to ampicillin, being the MIC of 8 ${\mu}g/ml$ or less and 53(27.2%) were susceptible to co-trimoxazole, being the MIC of TMP/SMZ 4/76 ${\mu}g/ml$ or less. S. flexneri type 2 was often resistant to both antimicrobic agents. 2. An increasing rate of resistant isolates was noted, particularly in the year of 1979. 3. Many isolates were resistant to both agents. Somewhat more cultures. were ampicillin susceptible and co-trimoxazole resistant than the other way around. It seems that the determination of species or even serotypes might be of help sometimes to select proper antimicrobic agent to control the infection. A routine antimicrobic susceptibility test of Shigella to both ampicillin and co-trimoxazole would be advisable for a better selection of chemotherapeutic agent.

• 한국미생물·생명공학회지
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• 제10권3호
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• pp.211-215
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• 1982

Streptomyces griseorubiginosus var. soyoensis 에 의하여 두가지의 항진균성 항생물질이 생성되었는데 하나는 trans-cinnamamide 이었고 다른 하나는 UV, IR, NMR, mass spectrum 및 화학반응의 결과로 새로운 tetraene계 화합물임이 밝혀져 이 물질을 Tetraene KM-A라 하였다. 본 물질의 항균성을 조사한 결과 곰팡이 및 효모류에 대하여는 강한 항진균성을 나타내었으나 항세균성은 없었다. 배지에 sterol류를 첨가하였을때 Tetraene KM-A의 항균력이 없어지는 것으로 보아 stesoid와 결함함을 알수 있고 항균작용도 이와 관련이 있는 것으로 판단하였다. Tetraene KM-A의 mouse 및 rat에 대한 복강주사에 의한 $LD_{50}$ 은 각각 84.3과 90.4mg/kg이였으며 mouse에 대만 경구독성은 1503mg/kg이었다.