• Mycobiology
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• 제43권2호
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• pp.137-149
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• 2015

In the search for novel potent fungi-derived bioactive compounds for bioinsecticide applications, crude ethyl acetate culture filtrate extracts from 110 mangrove fungal endophytes were screened for their toxicity. Toxicity tests of all extracts against brine shrimp (Artemia salina) larvae were performed. The extracts with the highest toxicity were further examined for insecticidal activity against Spodoptera litura larvae and acetylcholinesterase (AChE) inhibition activity. The results showed that the extracts of five isolates exhibited the highest toxicity to brine shrimp at 50% lethal concentration ($LC_{50}$) values of 7.45 to 10.24 ppm. These five fungal isolates that obtained from Rhizophora mucronata were identified based on sequence data analysis of the internal transcribed spacer region of rDNA as Aspergillus oryzae (strain BPPTCC 6036), Emericella nidulans (strains BPPTCC 6035 and BPPTCC 6038), A. tamarii (strain BPPTCC 6037), and A. versicolor (strain BPPTCC 6039). The mean percentage of S. litura larval mortality following topical application of the five extracts ranged from 16.7% to 43.3%. In the AChE inhibition assay, the inhibition rates of the five extracts ranged from 40.7% to 48.9%, while eserine (positive control) had an inhibition rate of 96.8%, at a concentration of 100 ppm. The extracts used were crude extracts, so their potential as sources of AChE inhibition compounds makes them likely candidates as neurotoxins. The high-performance liquid chromatography profiles of the five extracts differed, indicating variations in their chemical constituents. This study highlights the potential of culture filtrate ethyl acetate extracts of mangrove fungal endophytes as a source of new potential bioactive compounds for bioinsecticide applications.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.952-964
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• 2005

The diesel-degrading activities of biofilms sampled from petroleum-contaminated groundwaters in urban subway drainage systems were examined in liquid cultures, and the microbial populations of the biofilms were characterized by denaturing gel gradient electrophoresis (DGGE) and 16S rDNA sequence analysis. Biofilm samples derived from two sites (19 K and 20 K) at subway Station N and Station I could degrade around $80\%$ of applied diesel within 20 and 40 days, respectively, at $15^{\circ}C$, and these results were strongly correlated with the growth patterns of the biofilms. The closest phylogenetic neighbor of a dominant component in the 19 K biofilm was Thiothrix fructosivorans strain Q ($100\%$ similarity). Four dominant strains in the 20 K biofilm were closely related to Thiothrix fructosivorans strain Q ($100\%$ similarity), Thiothrix sp. CC-5 ($100\%$ similarity), Sphaerotilus sp. IF14 ($99\%$ similarity), and Cytophaga-Flexibacter-Bacterioides (CFB) group bacterium RW262 ($98\%$ similarity). Three dominant members in the Station I biofilms were very similar to uncultured Cytophagales clone CRE-PA82 ($91\%$ similarity), Pseudomonas sp. WDL5 ($97\%$ similarity), and uncultured CFB group bacterium LCK-64 ($94\%$ similarity). The microbial components of the biofilms differed depending on the sampling site. This is the first report on the isolation of clones highly similar to Thiothrix fructosivorans and Thiothrix sp. from biofilms in petroleum-polluted groundwaters, and the first evidence that these organisms may play major roles in petroleum degradation and/or biofilm-development.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1679-1687
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• 2009

Three parathion-degrading bacteria and eight pairs of bacteria showing syntrophic metabolism of parathion were isolated from rice field soils, and their genetic and phenotypic characteristics were investigated. The three isolates and eight syntrophic pairs were able to utilize parathion as a sole source of carbon and energy, producing p-nitrophenol as the intermediate metabolite during the complete degradation of parathion. Analysis of the 16S rRNA gene sequence indicated that the isolates were related to members of the genera Burkholderia, Arthrobacter, Pseudomonas, Variovorax, and Ensifer. The chromosomal DNA patterns of the isolates obtained by polymerasechain-reaction (PCR) amplification of repetitive extragenic palindromic (REP) sequences were distinct from one another. Ten of the isolates had plasmids. All of the isolates and syntrophic pairs were able to degrade parathion-related compounds such as EPN, p-nitrophenol, fenitrothion, and methyl parathion. When analyzed with PCR amplification and dot-blotting hybridization using various primers targeted for the organophosphorus pesticide hydrolase genes of previously reported isolates, most of the isolates did not show positive signals, suggesting that their parathion hydrolase genes had no significant sequence homology with those of the previously reported organosphophate pesticide-degrading isolates.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1269-1278
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• 2013

Crack remediation on the surface of cement mortar using microbiological calcium carbonate ($CaCO_3$) precipitation (MICP) has been investigated as a microbial sealing agent on construction materials. However, MICP research has never acknowledged the antifungal properties of calcite-forming bacteria (CFB). Since fungal colonization on concrete surfaces can trigger biodeterioration processes, fungi on concrete buildings have to be prevented. Therefore, to develop a microbial sealing agent that has antifungal properties to remediate cement cracks without deteriorative fungal colonization, we introduced an antifungal CFB isolated from oceanic islands (Dokdo islands, territory of South Korea, located at the edge of the East Sea in Korea.). The isolation of CFB was done using B4 or urea-$CaCl_2$ media. Furthermore, antifungal assays were done using the pairing culture and disk diffusion methods. Five isolated CFB showed $CaCO_3$ precipitation and antifungal activities against deteriorative fungal strains. Subsequently, five candidate bacteria were identified using 16S rDNA sequence analysis. Crack remediation, fungi growth inhibition, and water permeability reduction of antifungal CFB-treated cement surfaces were tested. All antifungal CFB showed crack remediation abilities, but only three strains (KNUC2100, 2103, and 2106) reduced the water permeability. Furthermore, these three strains showed fungi growth inhibition. This paper is the first application research of CFB that have antifungal activity, for an eco-friendly improvement of construction materials.

• 미생물학회지
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• 제39권2호
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• pp.108-113
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• 2003

디젤유로 오염된 토양으로부터 분리한 디젤 분해 우수 균주를 HS 균주로 명명하고, 각 균주의 디젤유 분해능과 특성을 조사하였다. 분리된 HS균주의 동정결과 HSI 균주는 Acinetobacter sp. HS2, HS3 균주는Pseudomonas sp.로 동정되었다. 최소배지에서 디젤유2%, pH 7.0,$25^{\circ}C$, 교반속도 200 rpm의 조건으로 5일간 배양한 결과 HSI 균주는 88% 이상의 높은 분해효율을 나타내었다. 소수성과 유화능의 측정 결과 HSI 균주가 가장 높은 소수성을 나타내었고, 유화능은 HS3 균주가 가장 높게 나타났다. 위의 결과를 토대로 액체 배양시 분해효율이 가장 높은 HSI 균주를 선택하여 토양배양을 실시한 결과 30일이 경과된 후 80%이상의 디젤유 분해효율을 나타내었고, 디젤유 분해효율은 미생물 활성과 비례하는 것으로 확인되었다. 따라서 신규 분리된 디젤유 분해균주는 높은 디젤유 분해능과 토양 생존능으로 실제 유류오염 환경에 적용이 가능할 것으로 사료된다.

• KSBB Journal
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• 제32권2호
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• pp.124-132
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• 2017

A methane-oxidizing bacterium was isolated from rice paddy field soil around Jeollanam-do province, Korea, and characterized. The isolate was gram-negative, orange pigmented and short rod ($1.1-1.2{\times}1.6-1.9{\mu}m$). It was catalase and urease-negative but oxidase-positive. The strain utilized methane and methanol as sole carbon and energy sources. It had an ability to grow with an optimum pH 7.0 and an optimum growth temperature $30^{\circ}C$. The strain was resistant to antibiotic polymyxin B but sensitive to streptomycin, kanamycin, ampicillin, chloramphenicol and rifampicin. The isolate required copper for their growth with concentration range of $2-25{\mu}M$, with an optimum of $10{\mu}M$. Under optimal culture condition, specific cell growth rate and generation time were found to be $0.046hr^{-1}$ and 15.13 hr, respectively. Phylogenetic analysis based on 16S rDNA sequences indicated that the strain formed a tight phylogenetic lineage with Methylomonas koyamae with a value of 99.4% gene sequence homology. So, we named the isolate as Methylomonas sp. SM4. 8.6 mM methanol was accumulated in the reaction mixture containing 70 mM sodium formate and 40 mM $MgCl_2$ (MDH inhibitor) under atmosphere of methane:air (40:60) mixture for 24 hr at $30^{\circ}C$.

• KSBB Journal
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• 제16권6호
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• pp.562-567
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• 2001

Styrene oxide 계열의 라세믹 에폭사이드 기질에 대한 입체선택적 가수분해능이 우수한 Aspergillus nigerr계열의 생촉매를 선발하였고, A.niger LK 유래의 EHase의 기질 특이성을 분석하였다. A. niger LK의 EHase는 benzene ring에 oxirane ring이 직접 연결되어 있는 styrene oxide, p-nitrostyrene oxide 기질에 대해서는 (R)-이성질체, benzene ring과 oxirane ring사이에 ether 등의 연결 chain이 있는 기질에 대해서는 (S)-이 성질체에 대한 입체선택적 가수분해능이 우수하였다. A niger LK의 EHase 유전자를 RT-PCR 방법으로 클로닝하였고, sequencing을 통해 다른 미생물 유래의 EHase와의 sequence identity 분석 등을 통해 특성을 분석하였다. Yeast 유래의 EHase와는 32% 수준의 sequence identity를 보였으며, Agrobacterisum, Corynebacterium 등의 박테리아 유래 EHase와는 identity가 매우 낮은 특성을 보였다. E. coli 숙주에서 발현된 재조합 EHase의 활성은 라세믹 에폭사이드 기질에 대한 입체선택적 가수분해 반응을 통해 확인할 수 있었다. 클러닝된 EHase의 보다 효율적인 발현 연구가 필요하며, 이러한 재조합 EHase는 고부가가치 광학활성 에폭사이드 제조를 위한 생물전환공정 시스템의 생촉매로 응용될 수 있을 것으로 기대된다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.450-455
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• 2005

To treat wastewater efficiently by a one-step process of nitrogen removal, a new strain of $N_2-producing$ bacteria from $NH{_4}{^+}$ under an aerobic condition was isolated and identified. By 16S-rDNA analysis, the isolate was identified as Enterobacter asburiae with 96% similarity. The isolate shows that the capacity of $N_2$ production under an oxic condition was approximately three times higher than that under an anoxic condition. The optimal conditions (pH, temperature and C/N ratio) of the immobilized isolate for $N_2$ production were found to be 7.0, $30^{\circ}C$ and 5, respectively. Under all the optimum reaction conditions, the removal efficiency of $COD_{Cr}$ and TN reached 56.1 and 60.9%, respectively. The removal rates of $COD_{Cr}$ and TN were highest for the first 2.5 hrs (with the removal $COD_{Cr}$ ratios of 32.1), and afterwards the rates decreased as reaction proceeded. For application of the immobilized isolate to a practical process of ammonium removal, a continuous bioreactor system exhibited a satisfactory performance at HRT of 12.1 hr, in which the effluent concentrations of $NH{_4}{^+}-N$ was measured to be 15.4 mg/L with its removal efficiency of 56.0%. The maximum removal rate of $NH{_4}{^+}-N$ reached 1.6 mg $NH{_4}{^+}-N/L/hr$ at HRT of 12.1 hr (with N loading rate of 0.08 $Kg-N/m^3-carrier/d)$. As a result, the application of the immobilized isolate appears a viable alternative to the nitrification-denitrification processes.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1575-1579
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• 2014

Background: There is a close relationship between Helicobacter pylori (H pylori)-specific factors and different gastroduodenal diseases. The present study aimed to investigate the prevalence of vacA d1, d2 genotypes in the H pylori isolates from patients with gastric adenocarcinoma, peptic ulcer disease (PUD) and gastritis in East Azerbaijan region, where the incidence of gastric cancer (GC) is high. Strains isolated from this area are likely to be of European ancestry. Materials and Methods: In this study, genotyping of the vacA d region of 115 isolates obtained from patients with different gastrodoudenal diseases was accomplished by PCR methods. In addition to PCR amplification of H pylori 16S rDNA, rapid urease tests or histological examination were used to confirm the presence of H pylori in biopsy specimens. Data were collected and analyzed using SPSS version 19. Results: Of the total of 83 H pylori isolates, 36 (43.4%) contained the d1 allele and 47 (56.6%) were subtype d2. The results of the multiple linear/logistic regression analysis showed high correlation between allele d1 and gastric adenocarcinoma or PUD. Conclusions: This study suggests that the H pylori vacA d1 genotype helps predict risk for gastric adenocarcinoma and PUD in East Azerbaijan, Iran.

• 한국식품과학회지
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• 제45권2호
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• pp.252-256
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• 2013

우리밀(금강밀)을 기질로 사용한 식초 생산을 위하여 초산 생성능이 우수한 초산균을 재래 식초로부터 분리하여 A. pasteurianus A8으로 동정하였다. 우리밀 엿기름의 제조를 위해 발아 조건을 살펴본 결과, $15^{\circ}C$에서 6일간 발아 시킨 밀의 amylase 활성이 608.4 unit으로 가장 높았다. A. pasteurianus A8 균주를 종균으로 사용하여 우리밀 알코올 발효액의 초산 발효 조건을 살펴본 결과, 발효온도 $30^{\circ}C$, 초기 알코올 농도 5.0%, 및 종균 접종량 5.0%에서 24일간 정치 발효하여 5.8%의 초산을 생산할 수 있었다.