• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.244-250
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• 2000

An ${\alpha}-glucosidase$ gene (aglA) from thermophilic Bacillus sp. DG0303 was cloned, sequenced, and expressed in Escherichia coli. The aglA was localized to the 2.1-kb PvuI-XmnI region within the 5.9-kb DNA insert of the gybrid plasmid pAG1. The gene consisted of an open reading frame of 1,686 bp with an unusual GTG initiation codon and TGA termination codon. The amino acid sequence deduced from the nucleotide sequence predicted a protein of 562 amino acid residues with a M, of 66,551 dalton. A comparative amino acid sequence analysis revealed that DG0303 ${\alpha}-glucosidase$ is related to bacillary oligo-1, 6-glucosidases. The Bacillus sp. DG0303 ${\alpha}-glucosidase$ showed a high sequence identity (36-59%) to the B. flavocaldarius, B. cereus, and B. thermoglucosidasius oligo-1, 6-glucosidases. The number of prolines in theses four ${\alpha}-glucosidases. was observed to increase with increasing thermostability of these enzymes. The cloned ${\alpha}-glucosidase was purified from E. coli $DH5{\alpha}$ bearing pAG1 and characterized. The recombinant enzyme was identical with the native enzyme in its optimum pH and in its molecular mass, estimated by sodium dodecy1 sulfate-polyacrylamide gel electrophoresis. The temperature optimum of the cloned ${\alpha}-glucosidase$ was lower than that of the native enzyme.

• Journal of Microbiology and Biotechnology
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• 제8권3호
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• pp.270-276
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• 1998

Extracellular ${\alpha}$-glucosidase was purified to homogeneity from moderately thermophilic Bacillus sp. DG0303. The thermostable ${\alpha}$-glucosidase was purified by ammonium sulfate fractionation, ion-exchange chromatography, preparative polyacrylamide gel electrophoresis (PAGE), and electroelution. The molecular weight of the enzyme was estimated to be 60 kDa by SDS-PAGE. The optimum temperature for the action of the enzyme was at $60^{\circ}C$. It had a half-life of 35 min at $60^{\circ}C$. The enzyme was stable at the pH range of 4.5~7.0 and had an optimum pH at 5.0. The enzyme preparation did not require any metal ion for activity. The thermostable ${\alpha}$-glucosidase hydrolyzed the ${\alpha}$-1,6-linkages in isomaltose, isomaltotriose, and panose, and had little or no activity with maltooligosaccharides and other polysaccharides. The $K_m$ (mM) for p-nitrophenyl-${\alpha}$-D-glucopyranoside (pNPG), panose, isomaltose, and isomaltotriose were 4.6, 4.7, 40.8, and 3.7 and the $V_{max}$(${\mu}mol{\cdot}min^-1$$mg^-1$) for those substrates were 5629, 1669, 3410, and 1827, respectively. The N-terminal amino acid sequence of the enzyme was MERVWWKKAV. Based on its substrate specificity and catalytic properties, the enzyme has been assigned to be an oligo-1,6-glucosidase.

• 미생물학회지
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• 제43권1호
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• pp.40-46
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• 2007

생태계가 파괴된 파로호에 수초대를 복원하는 방법으로 rubberized coconut fiber를 식생기반재로 사용한 인공식물섬을 2003년 8월에 설치하였다. 인공식물섬 식생기반재에서는 식물이 자랄 수 있을 정도로 영양염이 농축되어 꽂창포(Iris ensata), 노랑 꽃창포(Iris pseudoacorus), 갈대(Phragmites communis)등 식재된 식물이 잘 자랐다. 이 과정에서 세균의 역할을 알아보기 위하여 2004년 4월부터 10월까지 2주 간격으로 총세균수, 활성세균수, ${\beta}-glucosidase$, phosphatase를 조사한 결과 인공식물성 식생기반재의 공극수에서 각각 평균 $28.6{\times}10^{6}\;cells/ml,\;22.7{\times}10^{6}\;cells/ml,\;452.9nM/L/hr,\;16381.9nM/L/hr$로 조사되어 파로호 호수물보다 각각 10배, 15배, 22배, 38배 높았다. 그리고 영양염류농도는 총인과 충질소가 식생기반재 공극수에서 각각평균 1.06 mg/L, 12.5 mg/L으로 조사되어 호수물보다 12배, 3배 높았다. 이 결과 인공식물섬 식생기반재에서 새로운 생태계가 만들어졌으며, 이 생태계에서 세균이 중요한 역할을 하여 빈-중영양상태의 호수물에서도 식물이 잘 자랄 수 있었다.