• 농업과학연구
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• 제34권2호
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• pp.99-109
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• 2007

섬유소 분해균 Cellulomonas sp. CS 1-1에 대하여 종 수준으로 분류학적 위치를 규명하기 위하여 7개 type strain 균주와 함께 생리적 및 생화학적 특성을 조사하고 DNA 상등성 및 지방산의 조성 등을 분석하여 비교한 결과, CS 1-1의 콜로니 형태는 circular, entire, smooth, convex하며, 담황색을 띤 $0.3{\sim}0.5{\times}0.8{\sim}1.2{\mu}m$ 크기의 간균이었다. 생리학적 특징으로서 비운동성의 통성혐기성 중온균으로서 Gram양성, catalase양성, oxidase음성, 탄수화물 발효성 등의 표현형은 Cellulomonas 속의 타종과 동일하였으며, 특히 D-ribose, raffinose, rhamnose, xylitol, acetate, L-lactate, propionate, aspartate, proline 등 조사한 모든 탄소원의 이용성이 없었으며, 반면에 sacchrose, arabinose 및 amylose의 이용성은 양성으로 판정되었다. G+C 함량 74.76 mol %, 주요 지방산과 quinone 성분은 전형적인 Cellulomonas의 12-methyltetradecanoic acid (anteiso-$C_{15:1}$)과 MK-$9(H_4)$이었으며, DNA의 상동성 비율은 C. uda ATCC 491과 70%, C. fimi ATCC 15724와 54~59 %, C. gelida 및 C. bibula와도 46~48%의 상동성을 나타내었다. 이상의 결과는 CS1-1이 현재 Cellulomonas 속에 인정된 7개의 type species 중 C. uda ATCC 491 균주와 가장 높은 근연성을 나타냄으로서 C. uda에 속하는 novel species로 분류될 수 있다.

• Journal of Microbiology and Biotechnology
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• 제17권8호
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• pp.1291-1299
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• 2007

Two ${\beta}$-1,4-glucanases (DI and DIII fractions) were purified to homogeneity from the culture filtrate of a cellulolytic bacteria, Cellulomonas sp. CS 1-1, which was classified as a novel species belonging to Cellulomonas uda based on chemotaxanomic and phylogenetic analyses. The molecular mass was estimated as 50,000 Da and 52,000 Da for DI and DIII, respectively. Moreover, DIII was identified as a glycoprotein with a pI of 3.8, and DI was identified as a non-glycoprotein with a pI of 5.3. When comparing the ratio of the CMC-saccharifying activity and CMC-liquefying activity, DI exhibited a steep slope, characteristic of an endoglucanase, whereas DIII exhibited a low slope, characteristic of an exoglucanase. The substrate specificity of the purified enzymes revealed that DI efficiently hydrolyzed CMC as well as xylan, whereas DIII exhibited a high activity on microcrystalline celluloses, such as Sigmacells. A comparison of the hydrolysis patterns for pNP-glucosides (DP 2-5) using an HPLC analysis demonstrated that the halosidic bond 3 from the nonreducing end was the preferential cleavage site for DI, whereas bond 2, from which the cellobiose unit is split off, was the preferential cleavage site for DIII. The partial N-terminal amino acid sequences for the purified enzymes were $^1Ala-Gly-Ser-Thr-Leu-Gln-Ala-Ala-Ala-Ser-Glu-Ser-Gly-Arg-Tyr^{15}$-for DI and $^1Ala-Asp-Ser-Asp-Phe-Asn-Leu-Tyr-Val-Ala-Glu-Asn-Ala-Met-Lys^{15}$-for DIII. The apparent sequences exhibited high sequence similarities with other bacterial ${\beta}$-1,4-glucanases as well as ${\beta}$-1,4-xylanases.

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1789-1796
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• 2007

A ${\beta}$-glucosidase with the molecular mass of 160,000 Da was purified to homogeneity from cell extract of a cellulolytic bacterium, Cellulomonas uda CS1-1. The kinetic parameters ($K_m$ and $V_{max}$) of the enzyme were determined with pNP-cellooligosccharides (DP 1-5) and cellobiose. The molecular orbital theoretical studies on the cellulolytic reactivity between the pNP-cellooligosaccharides as substrate (S) molecules and the purified ${\beta}$-glucosidase (E) were conducted by applying the frontier molecular orbital (FMO) interaction theory. The results of the FMO interaction between E and S molecules verified that the first stage of the reaction was induced by exocyclic cleavage, which occurred in an electrophilic reaction based on a strong charge-controlled reaction between the highest occupied molecular orbital (HOMO) energy of the S molecule and the lowest occupied molecular orbital (LUMO) energy of the hydronium ion ($H_3O^+$), more than endocyclic cleavage, whereas a nucleophilic substitution reaction was induced by an orbital-controlled reaction between the LUMO energy of the oxonium ion ($SH^+$) protonated to the S molecule and the HOMO energy of the $H_2O_2$ molecule. A hypothetic reaction route was proposed with the experimental results in which the enzymatic acid-catalyst hydrolysis reaction of E and S molecules would be progressed via $SN_1$ and $SN_2$ reactions. In addition, the quantitative structure-activity relationships (QSARs) between these kinetic parameters showed that $K_m$ has a significant correlation with hydrophobicity (logP), and specific activity has with dipole moment, respectively.