Thermostable exo-inulinase production by semicontinuous cultivation of membrane-immobilized Bacillus sp. 11 cells

摘要

Growing cells of thermophilic Bacillus sp. 11, producer of a thermostable exo-inulinase, were immobilized on formaldehyde-ac- tivated polysulphone membranes. The biocatalysts obtained showed 1.5-2 fold higher enzyme yields (inulinase and invertase activities) than those of free cells. Active cell growth and no alternations of the membrane structure were observed by scanning electron microscopy (SEM) after 10 days (five cycles) repeated batch cultivation. The residual enzyme activities of the biocatalysts were 60-90/100 of their initial activities at the end of fifth run of semicontinuous cultivation.