| 摘要 |
<p>PURPOSE:To easily obtain a large quantities of the subject substance by transforming a cell with a plasmid DNA containing a DNA fragment originated from a specific microorganism and culturing the obtained transformant in a medium. CONSTITUTION:Ruminococcus albus is cultured in a medium containing glucose, etc., and the obtained microbial cell is extracted to obtain a DNA fragment (A) having a base sequence of formula and coding a genetic information of a neutral cellulase. A part of the component A is mutated to obtain a mutated DNA fragment (B) effective in (a) coding a protein corresponding to the matured protein of said neutral cellulase provided that the 15 or 24 amino acids from the amino terminal are deleted, (b) coding a slightly acidic cryotolerant cellulase, etc. A microbial strain (FERM P-10624) transformed with a plasmid DNA containing the component B is cultured in a medium and the cultivation product is extracted and purified to obtain the objective slightly acidic and slightly cryotolerant cellulase having a molecular weight of 35,000+ or -5,000 dalton, exhibiting maximum activity at pH5-7 and 20-35 deg.C and keeping >=80% of the activity after keeping at 37 deg.C for 1hr.</p> |
