분리균 Pseudomonas sp. LBC-505에 의한 천연섬유소의 당화

Saccharification of Natural Cellulosic Materials by the Isolated Pseudomonas sp. LBC-505

섬유성 물질을 발효기질로서 사용하기 위하여, 분리균 Pseudomonas sp. LBC-505의 cellulase를 이용하여 여러 종류의 천연 섬유성 물질에 대한 당화실험을 행하였다. Cellulase 복합체의 생산은 glucose에 의하여 저해되었고 CMC, avicel, 밀기울, 볏짚 등의 섬유성 물질에 의해 유도되었으며, 55(w/v) 밀기울 배지에서 최대 효소활성을 나타내었다. CMCase 와 xylanase의 최적 효소 반응온도는$50^{\circ}C$였으며, $\beta$-glucosidase는 $55^{\circ}C$ 였다. 또한, 이들 효소의 최적 반응 pH 는 모두 6.6이었다. 조효소 단독처리에 의한 천연섬유소의 당화율은 낮게 나타났으나, 5%(v/v) HCl로 실온에서 24시간 전처리한 후 효소반응을 행한 결과 가수분해율이 18.4%(w/w)로 볏집이 가장 양호하였으며, 구성당은 주로 glucose, xylose 및 cellobiose 였다.

In order to utilize natural cellulosic materials as a fermentative substrate, saccharification of a various kind of native cellulosic materials was performed by using cellulase from the isolated strain, Pseudomonas sp. LBC-505 which potently produced cellulase complex and xylanase. Cellulase complex production was repressed by the low concentration of glucose, induced by cellulosic compounds such as CMC, wheat bran and rice straw et al. and showed to be highest on the PY-CMC medium containing 5% (w/v) wheat bran instead of CMC. Optimal temperature for enzyme reactions of CMCase and xylanase was $50^{\circ}C$, and $55^{\circ}C$ for $\beta$-glucosidase. Optimal pH for these enzyme reaction was 6.6. Rate of saccharification for natural cellulose was low by the treatment of crude enzyme. Among their substrates, rice straw was the most effective substrate of enzymatic reaction in this work. After treating rice straw with 5% (v/v) HC1 and hydrolysing with crude enzyme, rate of saccharification was 18.4% (w/w) on dry substrate. Sugars of cellulosic hydrolyzate mainly contained glucose, xylose and cellobiose.