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- 학과정보 : 생물학과 미생물전공 (검색결과 236 건)
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동해 심층수에서 분리한 Zhongshania 속 신종 세균의 동정
Many bacteria have not been reported yet from the deep sea ocean environment, due to the presence of the many unculturable bacteria. In this study, are novel bacterium was isolated from the deep sea water of Donghae, Korea for the purpose of securing biological resource. The isolated strain DSW25-10 is Gram-staining-negative, rod-shaped and a motile bacterium by single polar flagellum. Growth of strain DSW25-10 was observed the growth at 4-35℃ (optimum, 20-35°C), pH 5.5-9.0 (optimum, pH 7.0) and in the presence 0-6% (w/v) NaCl (optimum, 0.5-2%). Strain DSW25-10 contained ubiquinone-8 (Q-8) as the sole isoprenoid quinone and sum in feature 3 (C16:1w7c/C16:1w6c), summed feature 8 (C18:1w7c / C18:1w6c), C16:00 and C17:1 ω8c as the major fatty acids. The genomic DNA G+C contents of strain DSW25-10 was 49.1 mol%. Analysis of the 16S rRNA gene sequence of the strain showed an affiliation with the genus Zhongshania, sharing 97.2% and 97.0% sequence similarities with type strains of Zhongshania guokunii ZS5-23T and Zhongshania borealis CL-AS9T, respectively. The DNA-DNA hybridization values for strains between DSW25-10 and Zhongshania guokunii ZS5-23T, and DSW25-10 and Zhongshania borealis CL-AS9T were 13.4% and 51.7%, respectively. Base on the data presented here, it is considered that strain DSW25-10 represents a novel species of the genus Zhongshania.
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Prevention of neonatal diarrhea in calves plays a significant role in improving their overall performance during their life span. Due to growing concerns over multi-drug resistance of bacteria against certain antibiotics, probiotics are emerging as promising alternative to prevent diarrhea in newborn calves. In this study, Lactobacillus reuteri strain LRb was isolated from dairy calves less than 7 days, and its probiotic properties were evaluated in vitro and in vivo. In vitro experiments on L. reuteri strain LRb showed good growth curve and survival rate of the bacteria in normal condition and harsh intestinal environment, respectively. In addition, assays using this isolated strain showed effective antimicrobial activity against enterotoxigenic Escherichia coli (ETEC) and Salmonella enterica Typhimurium. Animal experiments were performed using a mouse model to evaluate the probiotic effect of L. reuteri strain LRb. This strain showed relatively weak potential in preventing ETEC infection, but had great effect on the restoration of the intestinal villi and crypt. Furthermore, histopathological investigation of this strain revealed that it was effective in preventing S. enterica Typhimurium infection. Mice fed with this strain showed less inflammatory response as well as a 50% preventive effect against S. enterica Typhimurium infection. Thus, based on these results, L. reuteri strain LRb may be considered as an effective alternative to antibiotics, or the treatment of diarrhea in neonatal calves, which is caused by enterotoxigenic E. coli and S. enterica Typhimurium. 신생기의 설사는 송아지의 생존에 치명적인 영향을 미칠 뿐만 아니라 성장 이후의 생산성에 있어서도 영향을 미치기 때문에 소 사양관리에 있어서 전세계적으로 가장 중요한 질병으로 여겨지고 있다. 신생 송아지의 설사를 치료하기 위해 전통적으로 항생제가 사용되어 왔지만, 최근 들어 항생제 다재내성균의 등장 및 유기 낙농업의 발달로 항생제의 사용을 줄이기 위한 방법들이 모색되어 왔고, 그 방편으로 유산균의 이용에 대한 연구가 진행되어 왔다. 기존의 연구들에서는 대부분 생후 1달 이내의 송아지에서 유산균을 분리하여 그 효능을 평가했지만, 이번 연구에서는 송아지의 식이사양 변화를 고려하여 포유에만 식이를 의존하는 시기인 생후 1주일 이내의 송아지만을 대상으로 장내 유산균을 분리하여 in vitro 및 in vivo 실험을 진행하였다. 고형사료를 먹기 시작하면서 송아지 장 내의 정상미생물총이 크게 변화하는데, 그 변화 이전에 정상 송아지 장 내에서 우점종을 차지하는 Lactobacillus reuteri 가 장내 미생물총의 안정에 중요한 역할을 한다고 가정하였다. In vitro 실험에서는 분리된 L. reuteri LRb의 성장능력 장내 환경에서의 생존성 및 항균능력을 평가하였는데, 24시간의 빠른 성장속도 및Enterotoxigenic Escherichia coli 와 Salmonella enterica Typhimurium에 대한 뛰어난 항균능력, 장내 환경에 대한 강한 생존능력을 확인할 수 있었다. In vivo 실험에서는 마우스 모델을 대상으로 장 상피세포의 회복 및 살모넬라에 대한 감염 방어능을 평가했다. L. reuteri LRb를 투여한 그룹에서 enterotoxigenic E. coli에 대한 감염의 방어는 나타나지 않았지만 6일 후의 장 상피세포 회복에서 뚜렷한 효과를 보이는 것을 확인할 수 있었고, S. Typhimurium 감염평가에 있어서는 감염에 대한 예방과 염증반응의 완화를 일으키는 것을 확인할 수 있었다. 결과적으로 이번에 신생 송아지에서 분리한 L. reuteri strain LRb는 송아지 설사를 일으키는 중요한 세균인 enterotoxigenic E. coli와 S. Typhimurium에 대해 항생제의 훌륭한 대체제가 될 수 있을 것으로 보인다.
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家兎를 利用한 isoniazid와 streptomycin의 生物學的 檢定實驗
The rabbit serum level for isoniazid(INH)was assayed by microbiologic tests using tubed dilutions of the serum, For streptomycint(SM)was assayed by microbiologic tests employing diffusion of the drugs from serum soaked paper discs into agar. The findings of above tests were examined from variations of drug concentration with time. The enhancing effectiveness of serum concentrations in combinations of INH with SM was compared with the activity of either INH or SM alone. The results were summarized as follows: l. In INH, peak serum concentrations of 0. 09±0.16μg/ml in INH alone and l. 33±0. 16μg/ml in combinations of INH with SM develop 30minute after ingestion of either INH alone or combinations of INH with SM. 2. In SM, peal serum concentrations of 11.23±0.44μg/ml in SM alone and 11.20±0.34μg/ml in combinations of INH with SM develop 1 hour after ingestion of either SM alone or combinations of INH with SM. 3. Over minimal inhibitory concentration(MIC, 0.2μg/ml) of INH was maintained during 3 hours and over MIC(4μg/ml)of SM was maintained during 4 hours in each drug alone and combinations of INH with SM. 4. The enhancing effectiveness of serum concentrations in combinations of INH with SM insignificant in comparison with the activity of either INH or SM alone. (P<0. 1, P<0. 5)
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음식물 퇴비로부터 신규 호기성 고온세균의 분리 및 특성 분석
A novel extremely thermophilic bacterium, strain FW80, was isolated from food waste compost in Jeongeup-si, Republic of Korea. Cells were Gram positive, spore-forming, strictly-aerobic and motile rods (2·0-4·0 × 0·6-0·8 μm) with peritrichous flagella. Strain FW80 grew at 50-85℃ (optimum 77℃), pH 6.0-10.0 (optimum pH 7.5) and 0.0-3.0% NaCl (optimum 1.0%). The optimal growth temperature of strain FW80 was higher than that of Thermaerobacter composti JCM 15650T (70℃) and showed the highest growth temperature in Genus Thermaerobacter. The isolate was heterotrophic and grew on yeast extract and peptone as a nutrient substrate. However, the substrates were not available : dextrin, arabinose, cellobiose, fructose, galactose, D-(+)-glucose, inositol, lactose, maltose, mannitol, mannose, raffinose, sucrose, trehalose, alanine, asparagine, aspartate, glutamate, histidine, leucine, phenylalanine, proline, serine, threonine, pyruvate, acetate, citrate, lactate, propionate, succinate, aminobutyric acid and glycerol. The G+C content of the genomic DNA was 71.2 mol%, as measured by the thermal denaturation method. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain FW80 was closely related to T. composti JCM 15650T (99.7%). However, DNA-DNA hybridization showed that DNA relatedness value for strain FW80 and T. composti JCM 15650T was below 19.49%. On the basis of physiological and molecular properties of strain FW80 is considered to represent a novel species of the genus Thermaerobacter.
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국내 임상분리 살모넬라균주의 혈청형 동정을 위한 Multilocus Sequence Typing 분석법의 적용
Salmonella is divided into two species and six subspecies according to the Kaffmann-White scheme and has more than 2,600 serotype. Each serotype was defined by the combination of the O-antigen and the two H-antigens, which were tested using antisera. Original serological methods have the disadvantage that all antiserum must be prepared and the shelf life of antiserum is short. If the mutation occurs in the antigen, the result may vary depending on the phenotype expressed. In this case, Multilocus Sequence Typing (MLST) method is used for replacing serotyping using antisera. The purpose of this study was to compare the results of serotyping with antisera and MLST analysis of 100 Salmonella strains of National Culture Collectin Pathgen (NCCP) bank to determine whether it could replace the traditional serotype identification method. 100 Salmonella strains consisted of 53 strains isolated from clinical isolate in Korea and 47 strains isolated from foreign country. As a result of cultivation of Salmonella, gray round colonies showed hemolysis in SBA (5% Sheep Blood Agar), and round black colonies were observed in SS (Salmonella-Shigella agar) and XLD (Xylose-lysine-deoxy- cholate agar), confirming the characteristic form of Salmonella. Biochemical identification using VITEK 2 (BioMeriux, France) resulted in more than 90% of the results. Serotypes were not confirmed by biochemical methods except for S. Typhi, S. Enteritidis, S. Typhimurium, and S. Paratyphi A, S. Paratyphi B, S. Paratyphi C. The results of the identification of Salmonella using Matrix-Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry (MALDI-TOF MS) showed that all of the scores were 2.0 or more, so that Salmonella genus could be identified, but there was a limit to the identification of serotype. As a result of MLST analysis, 53 serotypes were identified by 64 sequence types. Salmonella isolates in Korea showed 38 serotypes with 39 sequence types and foreign Salmonella strains showed 28 serotypes with 35 sequence types. As a result the serotypes identified by antisera and MLST analysis were compared, 97 (97%, 97/100) serotypes of Salmonella strains were matched. Phylogenetic tree analysis of 100 Salmonella strains showed that the same sequence types were grouped regardless of the isolates in Korea and foreign isolates, and the sequence type and serotype results were correlated. Therefore, it is possible to identify serotype by MLST analysis and it is expected to replace the serotype identification method using antiserum.
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