• Journal of Microbiology
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• 제43권6호
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• pp.572-576
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• 2005

This study focused on detecting catabolic genes for polycyclic aromatic hydrocarbons (PAHs) distributed in the reed rhizosphere of Sunchon Bay, Korea. These marsh and mud environments were severely affected by human activities, including agriculture and fisheries. Our previous study on microbial roles in natural decontamination displayed the possibility that PAH-degrading bacteria, such as Achromobacter sp., Alcaligenes sp., Burkholderia sp. and Pseudomonas sp. play an important decontamination role in a reed rhizosphere. In order to gain further fundamental knowledge on the natural decontamination process, catabolic genes for PAH metabolism were investigated through PCR amplification of dioxygenase genes using soil genomic DNA and sequencing. Comparative analysis of predicted amino acid sequences from 50 randomly selected dioxygenase clones capable of hydroxylating inactivated aromatic nuclei indicated that these were divided into three groups, two of which might be originated from PAH-degrading bacteria. Amino acid sequences of each dioxygenase clone were a part of the genes encoding enzymes for initial catabolism of naphthalene, phenanthrene, or pyrene that might be originated from bacteria in the reed rhizosphere of Sunchon Bay.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1490-1494
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• 2014

To probe the genomic properties of microbes thriving in desert lakes, we sequenced the full genome of a betaproteobacterial strain (SL110) belonging to the understudied genus Caenimonas of the family Comamonadaceae. This strain was isolated from a freshwater lake in the western Gobi Desert, Northern China. Its genome contains genes encoding carbon monoxide dehydrogenase, nitrate reductase, nitrite reductase, nitric oxide reductase, and sulfur oxidation enzymes, highlighting the potentially important contribution of this group of bacteria to the cycling of inorganic elements in nature. Unexpectedly, a coenzyme $F_{420}$ biosynthesis gene cluster was identified. A further search for $F_{420}$ biosynthesis gene homologs in genomic databases suggests the possible widespread presence of $F_{420}$ biosynthesis gene clusters in proteobacterial genomes.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.218-225
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• 2007

A lactic acid bacterium capable of anaerobic respiration was isolated from soil with ferric iron-containing glucose basal medium and identified as L. garvieae by using 16S rDNA sequence homology. The isolate reduced ferric iron, nitrate, and fumarate to ferrous iron, nitrite, and succinate, respectively, under anaerobic $N_2$ atmosphere. Growth of the isolate was increased about 30-39% in glucose basal medium containing nitrate and fumarate, but not in the medium containing ferric iron. Specifically, metabolic reduction of nitrate and fumarate is thought to be controlled by the specific genes fnr, encoding FNR-like protein, and nir, regulating fumarate-nitrate reductase. Reduction activity of ferric iron by the isolate was estimated physiologically, enzymologically, and electrochemically. The results obtained led us to propose that the isolate metabolized nitrate and fumarate as an electron acceptor and has specific enzymes capable of reducing ferric iron in coupling with anaerobic respiration.

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.96-104
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• 2019

Beauveria bassiana, one of the most common entomopathogenic fungi, has been isolated, pre defined and characterized in-house from soil of tea cultivation area. Experiments have been performed to verify the presence of chitinase as intracellular metabolite and its release as extracellular product rendering the spores with biopesticide activity. Although there are many responsible enzymes for the pest killer action of B. bassiana, binding property of chitinase depending on presence as well as absence of serine supplemented in the media has been studied with respect to the production and kinetics. A programmed investigation conclusively indicates that the isolated spore (hyphae) of B. bassiana has been metabolically enriched with the enzyme chitinase in presence of an externally added amino acid serine with its inhibitory kinetics.

• 한국균학회지
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• 제21권4호
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• pp.316-322
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• 1993

Examination by scanning electron microscopy and potato-dextrose agar medium showed that the dry seeds of R. raetam were externally free of fungi. When planted in sandy loam soil, the seeds become colonized with eleven soilborne fungal species. The fungi were isolated on cellulose agar, pectin agar and lignin agar media. Aspergillus flavus, A. niger, Penicillium capsulatum and Fusarium oxysporum had broad occurrence and recovered on the three media. The production of hydrolytic enzymes by the isolated fungi depends on the substrate and species. P. capsulatum, P. spinulosum and A. niger had wide enzymatic amplitude and they were able to produce cellulolytic, pectolytic and lignolytic activities on corresponding substrates as well as on seed coat containing media. The lignolytic activities of the isolated species except Chaetomium bostrychods and Trichoderma viride were enhanced on applying the seed coat materials as C-source rather than using lignin. Soaking R. raetam seeds in culture filtrates of the most fungi grown on seed coat supplemented media induced pronounced and distinct stimulating effect on seed germination. The most effective filtrates were those of P. capsulatum, P. spinulosum and Sporotrichum pulverulentum.

• 한국환경생태학회지
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• 제24권4호
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• pp.426-435
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• 2010

본 연구는 사문암 토양의 화학적 성질과 토양미생물량 및 토양효소 등 토양의 생물학적 활성을 대조구의 비사문암 토양과 비교하고, 사문암과 비사문암에서 공통으로 서식하는 새(Arundinella hirta)와 억새(Miscanthus sinensis var. purpurascens)의 낙엽이 입지가 다른 사문암지역과 비사문암 지역에서 분해될 때 분해율의 차이가 어떻게 유발되는지 9개월 동안 야외에서 교차 실험하였다. 사문암 토양은 비사문암 토양에 비하여 높은 pH, 낮은 dehydrogenase 와 urease활성을 나타내었으며 alkaliphosphatase의 활성은 높았다. 두 토양에서 microbial biomass-C와 N의 차이는 유의하지 않았으나 사문암 토양에서 microbial biomass-N함량이 더 높게 나타나 비사문암 토양에서 보다 낮은 토양의 C/N을 나타내는 원인이 되었다. 사문암지역에서의 낙엽분해실험에서는 사문암지역에서 획득한 새와 억새 낙엽이 각각 39.8%, 38.5%의 중량감소를 보였으며, 비사문암 토양에서 획득한 낙엽은 각각 41.1%, 41.7%의 중량감소를 나타내었다. 비사문암지역에서의 낙엽분해실험에서는 사문암낙엽이 46.8%, 42.2% 그리고 비사문암낙엽은 44.8%, 37.4%의 중량감소를 각각 보였다. 이러한 결과는 중금속을 포함하는 토양의 영향보다는 낙엽의 질적 차이가 분해율에 더 큰 영향을 미쳤음을 나타내준다. 일반적으로 낮은 C/N을 갖는 낙엽이 더 빨리 분해된다는 결과와는 달리 낮은 C/N을 갖는 사문암낙엽의 분해가 느린 것은 낙엽에 포함된 중금속의 저해가 낙엽의 C/N이나 lignin/N과 같은 낙엽의 질적 차이에서 유발되는 낙엽분해의 저해보다 큰 영양을 미친다는 결과를 보여주었다. 또한 낙엽분해가 진행되는 동안 낙엽내의 Cr, Ni과 Mg, Fe의 농도는 점차 증가하였으며 이러한 경향은 사문암지역에서 현저하였다.

• 한국환경농학회지
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• 제11권1호
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• pp.1-8
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• 1992

농약분해에 관여하는 monooxygenase와 esterase의 활성을 저해하는 것으로 알려진 PBO와 TPP를 첨가하여 제조한 신(新)다이아지논입제에 대하여 벼멸구에 대한 살충률을 조사하였고, 아울러 신(新)다이아지논 입제와 두효소를 저해하는 작용기작을 가지고 있는 tricyclazole, carbofuran 그리고 EPN을 혼합하여 제조한 혼합다이아지논입제에 대하여 담수토양중의 잔류경향을 조사하였다. 1. 살균토양과 비살균토양에서 신(新)다이아지논 입제(0.1% 첨가)의 반감기는 4.53일과 2.33일 이었고, 시판품에 비하여 각각 0.74일과 0.45일 주성분의 분해가 지연되었다. 2. 신(新)다이아지논입제(0.1% 첨가)의 벼멸구에 대한 살충률은 추천량에서는 12%, 추천 1/2량에서는 $30{\sim}60%$가 증가되었다. 3. 신(新)다이아지논 입제 (1%)중 PBO 첨가는 토양중 반감기가 0.44일 그리고 PBO-TPP첨가로 0.65일 지연되었다. 4. 혼합다이아지논 입제는 시판품에 비하여 tricyclazole, carbofuran 그리고 EPN첨가로 반감기가 2.61일, 1.04일 그리고 0.43일 지연되었으며, EPN+carbofuran을 첨가하여 제조한 혼합다이아지논 입제는 2.7일 연장되었다.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1868-1873
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• 2006

A novel microorganism that could degrade high molecular weight gellan was screened and isolated from soil. On gellan plate, the microorganism grew well and completely liquefied the plate. The gellan-degrading microorganism was isolated by pure culture on glucose and nutrient agar medium afterwards. The 16S rDNA sequence analysis and biochemical tests using an API 50CHB/20E kit revealed that the strain belonged to Bacillus sp. The isolate, named as Bacillus sp. YJ-1, showed optimum gellan-degrading activity in 0.5% gellan medium at pH 7.5 and 37$^{\circ}C$. The activity was measured and evaluated by the thiobarbituric acid and thin-layer chromatography method. Mass spectrometry revealed that the major gellan.. depolymerized product was an unsaturated tetrasaccharide consisting of $\Delta$4,5-glucuronic acid-(1$\rightarrow$4 )-$\beta$-D-glucose-(1$\rightarrow$4)- $\alpha$-L-rhamnose-(1$\rightarrow$3)-$\beta$-D-glucose, which is a dehydrated repeating unit of gellan, thus the enzyme was identified as gellan lyase. When the gellan was present in the medium, the gellan-degrading activity was much higher than that in glucose-grown cells. These results indicate that in the presence of gellan, Bacillus sp. YJ-1 is able to metabolize the gellan by inducing gellan-degrading enzymes that can degrade gellan into small molecular weight oligosaccharides, and then the gellan. depolymerized products are taken up by the cells and utilized by intracellular enzymes.

• Applied Biological Chemistry
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• 제33권2호
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• pp.154-160
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• 1990

토양 시료로 부터 선별과정을 거쳐 대두유를 응고시킬 수 있는 extracellular 대두유응고효소를 생산하는 균주를 분리하고 분리세균 K-324-7균주에 의한 효소생산의 확인과 형태적 생리적 성질을 조사한 결과 Bacillus cereus로 동정되었다. Bacillus K-324-7 분리균이 생산하는 대두유 응고효소는 황산암모늄 0.8포화 용액에서 가장 높은 활성을 나타내었으며, 최적활성 pH는 6.1이며, 최적활성온도는 $70^{\circ}C$이었다. 또한 pH 안정성은 pH $6.0{\sim}7.0$ 사이에서 안정하였고 열안정성은 $50^{\circ}C$ 이하의 온도에서 인정하였다. 한편 대두유 응고효소의 생산 배양조건을 검토한 결과 탄소원은 glucose 0.2%, 질소원은 peptone 0.2%, 무기염은 $KH_2PO_4$ 0.5%, pH는 6.5, 배양온도는 $35^{\circ}C$로 배양기간은 3일 정도가 적당하였으며 그 이상 배양하면 생성된 효소의 활성이 감소됨을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제38권4호
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• pp.475-480
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• 2010

Actinomycetes are Gram-positive soil bacteria and one of the most important industrial microorganisms due to superior biosynthetic capabilities of many valuable secondary metabolites as well as production of various valuable bioconversion enzymes. Among them are cytochrome P450 hydroxylase (CYP), which are hemoproteins encoded by a super family of genes, are universally distributed in most of the organisms from all biological kingdoms. Actinomycetes are a rich source of soluble CYP enzymes, which play critical roles in the bioactivation and detoxification of a wide variety of metabolite biosynthesis and xenobiotic transformation. Cyclosporin A (CyA), one of the most commonly-prescribed immunosuppressive drugs, was previously reported to be hydroxylated at the position of 4th N-methyl leucine by a rare actinomycetes called Sebekia benihana, leading to display different biological activity spectrum such as loss of immunosuppressive activities yet retaining hair growth-stimulating side effect. In order to improve this regio-selective CyA hydroxylation in S. benihana, previously-identified several secondary metabolite up-regulatory genes from Streptomyces coelicolor and S. avermitilis were heterologously overexpressed in S. benihana using an $ermE^*$ promoter-containing Streptomyces integrative expression vector. Among tested, SCO4967 encoding a conserved hypothetical protein significantly stimulated region-specific CyA hydroxylation in S. benihana, implying that some common regulatory systems functioning in both biosynthesis and bioconversion of secondary metabolite might be present in different actinomycetes species.