Biotechnol. Bioeng., Vol.41. 88-94, 1993

Enzymetic Production of Cyclodextrins from Milled Corn Starch in an Ultrafiltration Membrane Bioreactor

Tae-Jong Kim, Yun-Dong Lee, and Hak-Sung Kim

Cyclodextrin glucosyltransferase(CGTase) was found to be severely inhibited by cyclodextrins. In order to increase the conversion yield by reducing product inhibition and reuse the CGTase in the production of cyclodextrins from milled corn starch, an ultrafiltration membrane bioreactor system was employed. In a batch operation with ultrafiltration, the conversion yield was increased 57% compared with that without ultrafiltration. Operating conditions for the continous production of cyclodextrins in the membrane bioreactor were optimized by taking into consideration the filtration rate and the conversion yield as follows : initial starch concentration, 7%(w/v); starch feeding rate, 240mg/h; CGTase loading 350 units/initial gram starch. When cyclodextrins were continously produced in the memebrane bioreactor under optimized conditions, 340 units of CGTase was required to produce 1g of cyclodextrins for 48h, while in the case of conventional batch operation, 1g of cyclodextrins was produced for 24h by 1410 units of CGTase