• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1664-1671
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• 2010

A new biosurfactant producer was isolated from palm-oil-contaminated soil and later identified through morphology and DNA sequencing as the yeast-like fungus Exophiala dermatitidis. Biosurfactant production was catalyzed by vegetable oil, supplemented with a basal medium. The culture conditions that provided the biosurfactant with the highest surface activity were found to be 5% palm oil with 0.08% $NH_4NO_3$, at a pH of 5.3, with shaking at 200 rpm, and a temperature of $30^{\circ}C$ for a 14-day period of incubation. The biosurfactant was purified, in accordance with surfactant properties, by solvent fractionation using silica gel column chromatography. The chemical structure of the strongest surface-active compound was elucidated through the use of NMR and mass spectroscopy, and noted to be monoolein, which then went on to demonstrate antiproliferative activity against cervical cancer (HeLa) and leukemia (U937) cell lines in a dose-dependent manner. Interestingly, no cytotoxicity was observed with normal cells even when high concentrations were used. Cell and DNA morphological changes, in both cancer cell lines, were observed to be cell shrinkage, membrane blebbling, and DNA fragmentation.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1841-1851
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• 2019

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.

• Journal of Applied Biological Chemistry
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• 제48권4호
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• pp.183-186
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• 2005

Arabidopsis AHL gene encodes a 3'(2')-phosphoadenosine 5'-phosphate (PAP)-specific phosphatase that plays a role in the sulfate activation pathway. We complemented E. coli cysQ mutant defective in cysteine biosynthesis with the AHL gene. AHL cDNA was cloned into the prokaryotic expression vector pKK388-1 and transformed into the bacterial mutant. Since cysQ mutant is a leaky cysteine auxotroph only under aerobic conditions, the bacteria were grown in liquid media with vigorous shaking to provide more aeration. In cysteine-free medium, cysQ mutant and the mutant harboring empty vector did not grow well, whereas cells harboring AHL cDNA exhibited significantly improved growth with doubling time of approximately 3 h. cysQ is known to encode a 3'(2'),5'-diphosphonucleoside 3'(2')-phosphohydrolase (DPNPase). However, our data suggest that cysQ protein has PAP-specific phosphatase activity in addition to DPNPase activity. Microbial complementation procedure described in this paper is useful for structure-activity studies of PAP-specific phosphatases identified from microbes and plants.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1979년도 춘계학술대회
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• pp.113.2-114
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• 1979

$\beta-Galactosidase$ is an enzyme which catalizes hydrolysis of lactose, a natural substrate, to glucose and galctose and transferring some monosac-charide units to active acceptors as sugar or alcohol. The occurence of $\beta-Galactosidase$ is known in various microorganisms, animals and higher plants and has been studied by many investigatigators. Especially, a great deal of articles for the enzyme of E. coli have been presented in genetic control mechanism and induction-repression effects of proteins, On the other hand, in the dairly products industry, it is important to hydrolyes lactosd which is the principal sugar of milk and milk products. During the last few years, the interest in enzymatic hydrolysis of milk lactose has teen increased, because of the lactose intolerence in large groups of the population. Microbial $\beta-Galactosidases$ are considered potentially most suitable for processing milk to hydrolyse lactose and, in recent years, the immobilized enzyme from yeast has been examined. Howev, most of the microbial $\beta-Gal$ actosidase are intracellular enzymes, except a few fungal $\beta-Gala-$ ctosidases, and extracellular $\beta-Galactosidase$ which may be favorable to industrial applieation is not so well investigated. On this studies, a mold producing a potent extracellular $\beta-Galactosidase$ was isolated from soil and identified as an imperfect fungus, Beauveria bassians. In this strain, both extracellular and intracellular $\beta-Galactosidases$ were produced simultaneously and a great increase of the extracellular production was acheved by improving the cultural conditions. The extracellular enzyme was purified more than 1, 000 times by procedures including Phosphocellulose and Sephadex G-200 chromatographies. Several characteristics of the enzymewas clarified with this preparation. The enzyme has a main subunit of molecular weight of 80, 000 which makes an active aggregate. And at neutral pH range, it has optimum pH for activity and stability. The Km value was determined to be 0.45$\times$10$^{-3}$ M for $o-Nitrophenyl-\beta-Galactoside.$ In any event, it is interesting to sttudy the $\beta-Galactosidase$ of B. bassiana for the mechanism of secretion and conformational structure of enzyme.

• Journal of Microbiology and Biotechnology
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• 제20권5호
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• pp.925-934
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• 2010

Three typical biological solid wastes, namely, animal manure, garbage, and sewage sludge, were compared with regard to the composting process and the changes in microbial community structure. The effects of different bulking agents such as rice straw, vermiculite, sawdust, and waste paper were compared in manure compost. The differences in the microbial community were characterized by the quinone profile method. The highest mass reduction was found in garbage composting (56.8%), compared with manure and sludge (25% and 20.2%, respectively). A quinone content of $305.2\;{\mu}mol/kg$ was observed in the late stage of garbage composting, although the diversity index of the quinone profile was 9.7, lower than that in manure composting. The predominant quinone species was found to be MK-7, which corresponds to Gram-positive bacteria with a low G+C content, such as Bacillus. The predominance of MK-7 was especially found in the garbage and sludge composting process, and the increase in quinones with partially saturated long side-chains was shown in the late composting process of manure, which corresponded to the proliferation of Actinobacteria. The effects of different bulking agents on the composting process was much smaller than the effects of different raw materials. High organic matter content in the raw materials resulted in a higher microbial biomass and activity, which was connected to the high mass reduction rate.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.232-239
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• 2006

The microbial activity and bacterial community structure of activated sludge reactors, which treated free cyanide (FC), zinc-complexed cyanide (ZC), or nickel-complexed cyanide (NC), were studied. The three reactors (designated as re-FC, re-ZC, and re-NC) were operated for 50 days with a stepwise decrease of hydraulic retention time. In the re-FC and re-ZC reactors, FC or ZC was almost completely removed, whereas approximately 80-87% of NC was removed in re-NC. This result might be attributed to the high toxicity of nickel released after degradation of NC. In the batch test, the sludges taken from re-FC and re-ZC completely degraded FC, ZC, and NC, whereas the sludge from re-NC degraded only NC. Although re-FC and re-ZC showed similar properties in regard to cyanide degradation, denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA gene of the bacterial communities in the three reactors showed that bacterial community was specifically acclimated to each reactor. We found several bacterial sequences in DGGE bands that showed high similarity to known cyanide-degrading bacteria such as Klebsiella spp., Acidovorax spp., and Achromobacter xylosoxidans. Flocforming microorganism might also be one of the major microorganisms, since many sequences related to Zoogloea, Microbacterium, and phylum TM7 were detected in all the reactors.

• 대한환경공학회지
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• 제31권10호
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• pp.919-926
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• 2009

혐기성 암모늄 산화공정을 안정화시키기 전에 많은 양의 식종 미생물 투여가 필요하므로 혐기성 암모늄 산화균의 농후배양은 실규모의 혐기성 암모늄 산화 반응기를 운영할 때 필수적인 과정이다. 본 연구에서는 활성슬러지 미생물을 식종한 연속 회분식 반응기를 이용하여 혐기성 암모늄 산화균을 농후배양하고, 미생물 군집구조의 변화를 관찰하여 농후배양 결과를 검증하였다. 혐기성 암모늄 산화균의 농후배양은 70일간 시행되었고, 농후배양 후 활성시험에서 $NH_4\;^+$와 $NO_2\;^-$의 기질제거효율이 각각 98.5%와 90.7%로 관찰되어 혐기성 암모늄 산화균의 배양이 성공적으로 수행된 것으로 판단되었다. 계통분류학적 분지도 작성 결과, 다양하였던 Planctomycetes 문(phylum)의 미생물 군집구조가 농후배양 이후에 현저하게 단순해졌다는 것이 밝혀졌다. 농후배양 이후 발견된 36개의 clone들 모두가 혐기성 암모늄 산화균이었으며, Candidatus Brocadia (36%) 와 Candidatus Anammoxoglobus (64%) 속(genus)에 속하였다. RTQ-PCR (real-time quantitative PCR)을 통해 혐기성 암모늄 산화균을 정량한 결과, 혐기성 암모늄 산화 상향류식 연속 배양기에서 1년 이상 선택 배양된 붉은색 혐기성암모늄 산화 입상 슬러지에 비해 혐기성 암모늄 산화균의 16S rDNA 농도가 74.8%인 것으로 나타났다. 상기의 분자생물학적 분석을 통해 70일간 농후배양된 활성슬러지가 혐기성 암모늄 산화 실용화 공정의 접종 미생물로 활용 가능할 것으로 판단되었다.

• 한국유기농업학회지
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• 제27권4호
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• pp.479-499
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• 2019

본 연구는 제주지역 무 주산지에서 재배 방법(유기 vs. 관행)과 토양 종류(화산회토 vs. 비화산회토)에 따른 토양의 화학적 특성, 미생물 활성 그리고 미생물 군집 조성을 분석하고 요인간 연관성을 구명하기 위하여 수행하였다. 전반적으로 유기와 관행의 재배 방식에 따른 토양 화학성은 처리간 뚜렷한 경향을 보이지는 않았으나 토양 미생물체량, 효소 활성, 종 풍부도와 다양성 그리고 미생물 군집 분포 등은 유의한 차이를 보였다. 반면에 토양 종류에 따른 화학성과 미생물 군집 분포 등 미생물학적 특성은 뚜렷한 차이를 보였다. 특히 유기재배 토양에서 관행 대비 토양의 세균, 방선균 및 사상균 그리고 미생물체량이 증가하였으며, Org-NA 토양에서 탈수소효소 활성, 종 풍부도(Chao 1) 그리고 종 다양성(Phyrogenetic diversity) 지수가 가장 높았다. 무 재배 토양에 분포하고 있는 주요 세균 문은 Proteobacteria, Acidobacteria, Chloroflexi, Firmicutes 그리고 Actinobacteria 등 5종이었으며 재배 방법 및 토양 종류에 관계없이 Proteobacteria 문이 화산회토에서 25.9%, 비화산회토에서 21.9~24.9%로 가장 높은 분포를 보였다. 그리고 대체로 화산회토와 비화산회토 토양 종류별로 유사한 군집 조성을 보였으며, 화산회토에서는 재배 방법별 주요 문의 군집 조성은 큰 차이가 없었으나 비화산회토에서는 차이를 보였다. 특히, Firmicutes는 Org-NA 토양에서 21.0%, Acidobacteria는 Con-A에서 21.6%로 가장 높은 분포를 보였는데 대체로 화산회토와 관행재배 토양에서 높은 경향을 보였다. 또한 재배 방법 및 토양 종류별 미생물 군집을 대표하는 바이오마커를 찾기 위하여 LEfSe 분석을 실시한 결과, Firmicutes 문의 분포가 비화산회토와 유기재배 토양에서 유의하게 증가하였다. 그리고 토양 화학성 중에서 총유기탄소 함량, 유효인산 그리고 치환성칼륨 함량은 Firmicutes 등 주요 세균 문과 유의한 상관관계를 보였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제10권2호
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• pp.52-58
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• 2005

본 연구는 사염화에틸렌(Perchloroethylene) 또는 트리클로로에틸렌(Trichloroethylene)으로 오염된 국내 지하수 내에 국외에서 보고된 환원성 탈염소화 미생물의 존재 유무와 사염화에틸렌의 생물학적 탈염소화 활성도를 평가하였다. 마이크로코즘 테스트(microcosm tests)는 4개의 오염지역(창원 A, 창원 B, 부천 및 양산) 지하수와 다양한 전자공여체 (sodium lactate, sodium propionate, sodium butyrate, sodium fumarate)를 이용하여 수행하였다. 단일 전자공여체 와 창원 A 혹은 창원 B 지하수를 주입한 전 마이크로코즘에서 사염화에틸렌 완전 탈염소화 분해 시 발생하는 최종 산물인 에틸렌이 배양 90일 후에 검출되었고, 부천 혹은 양산 지역의 지하수를 주입한 마이크로코즘에서는 배양 90 일 후 시스-1,2-디클로로에틸렌(cis-1 ,2-Dichloroethylene)만이 검출되었고, 염화비닐(Vinyl chloride) 과 에틸렌은 검출되지 않았다. 완전 탈염소화 생분해가 확인된 창원 B 지역 지하수와 불완전 탈염소화 생분해가 확인된 양산 지역 지하수 내 미생물 군집을 비교하기 위해 분자생물학적 방법을 이용한 실험을 수행하였다. 창원 B 지역 지하수의 클론 라이브러리(Clone library)에서 사염화에틸렌 완전 탈염소화 미생물, uncultured bacterium clone DCE47과 매우 유사한 염기서열 클론이 확인되었다. 그러나 양산 지역의 클론 라이브러리에서는 기존의 염화에틸렌 탈염소화 미생물과 유사한 염기서열 클론이 확인되지 않았다. 본 연구 결과를 통하여 국내 일부 지역의 지하수 내에 사염화에틸렌을 완전 탈염소화하여 무해한 에틸렌으로 분해하는 미생물이 존재함을 확인하였고, 적절한 전자공여체를 공급하는 경우 그 분해 활성도가 증가함을 확인하였다. 이 결과는 사염화에틸렌 혹은 트리클로로에틸렌으로 오염된 국내 지하수를 경제적인 공법인 환원성 탈염소화 생물학적 공정으로 복원할 수 있는 기능성을 보여주는 중요한 지표라고 사료된다.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.35-40
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• 1999

Alternan known as a kind of dextran is a linear and cyclic polysaccharide which is synthesized with sucrose by alternaansucrase (EC2.4.1.140) of Leuconostoc mesenteroides. But this polysaccharide is different from dextran in its structure and other properties. For the purpose of applying alternan for the food, cosmetic, and pharmaceutical industries, we isolated an excellent alternan-porducing strain, Leu. mesenteroides CBI-110. The optimum culture conditions were studied to improve the yield, and the activity of alternansucrase was increased up to 33U/ml in the optimum culture media. The concentrations of $Mn^{2+}$ and $Cu^{2+}$ ions were 0.01% and 0.03%, respectively, for the effective production of alternan. Finally, we obtained 25.6g/L of alternan.