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RISS 인기검색어
- 검색키워드
- 저자 : Mohamed A . Abdel - Naby (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Enzymatic Hydrolysis of Pretreated Chitin by Aspergillus carneus Chitinase
Abdel, Naby.,Mohamed, A.,Kwon, Dae Young 한국미생물 · 생명공학회 1992 Journal of microbiology and biotechnology Vol.2 No.3
Studies of the pretreatment of chitin and its subsequent hydrolysis by Aspergillus carneus chitinase are reported. Ball milling was found to be the most effective way among the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentrations on the rate and extent of the hydrolysis process. It was found that the successive addition of enzyme improved the saccharification yield. Significant product inhibition of the chitinase was observed when N-acetylglucosamine concentration was 3.6% or higher. Adsorption of enzymes to the substrate occurred during a 24 hr hydrolysis period. An initial rapid and extensive adsorption occurred, followed by gradual desorption which increased during the time of reaction. Intermediate removal of the hydrolyzate and continuation of the hydrolysis by adsorbed enzyme on the residual chitin was also investigated. A total of 75.4g/ℓ reducing sugars, corresponding to 69.2% saccharificaton yield (as N-acetylglucosamine) was obtained. In addition an increase in the amount of recoverable enzymes was observed under these conditions. Evidence presented here suggests that the technique, whereby the free enzymes in the recovered hydrolyzate are re-adsorbed onto the new substrate, may provide a means of recirculating the dissolved enzymes.
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The Production of Xylanase and β-Xylosidase by Aspergillus niger NRC 107
Abdel Naby, Mohamed A.,Kwon, Dae Young 한국산업미생물학회 1992 한국미생물·생명공학회지 Vol.20 No.5
Hemicellulose를 효소에 의하여 분해시키기 위하여 Aspergillus niger NRC 107로부터 xylanase와 β-xylosidase의 생산 조건에 대하여 조사하였다. 이들 효소 생산 최적 pH는 6.0이었으며 탄소원 중 corn-cob xylan과 질소원 중 Na_2N0_3이 효소 생산에 제일 좋은 기질이었으며 이들의 최적농도는 각각 15g/ℓ와 2.67g/ℓ이다. 이들 효소는 인산염(KH_2P0_4)과 Tween-80의 농도를 조절하므로 수율을 높일 수 있으며 wheat bran은 xylanase의 생산에 L(-) sorbose는 β-xylosidase의 생산에 좋은 영향을 주었다. 이와같이 이 Aspergillus niger NRC 107의 회분식 배양에서 이들 효소에 영향을 미치는 생산조건을 최적화한 결과 xylanase는 39.43 units/㎖, β-xylosidase는 4.2 units/㎖까지 생산할 수 있었다. The production of xylanase and β-xylosidase was investigated in submerged culture of Aspergillus niger NRC 107. The maximum production occurred when the pH was controlled at 6.0 during the fermentation. Among the various carbon sources investigated, corn-cob xylan(1.5%, w/v) yielded maximal production of the enzymes. The NaNO_3 was the most favorable nitrogen source for enzyme production and KH_2P0_4 concentration at 0.3%(w/v) was found to be optimum. Incorporation of wheat bran to the culture medium improved xylanase production. Addition of L(-) sorbose to the culture medium promoted the secretion of β-xylosidase. It was possible to increase the production of xylanase (39.43 units/㎖) and that of β-xylosidase (4.2 units/㎖) by submerged culturing the A. niger NRC 107 in the modified medium.
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