Continuous Production of Sorbitol with Zymomonas mobilis in a Packed Bed Reactor

Zymomonas mobilis에 의한 Packed Bed Reactor를 이용한 연속적인 sorbitol의 형성

The purpose of this study is to develop a continuous process for sorbitol production using Zymomonas mobilis immobilized in K-carra-geenan. The glutaraldehyde cross-linking of toluene-treated cells immobilized in alginate or chitin showed high enzyme stability for long period. However, loss of enzyme activity was observed at 23% during 210h. In order to investigate the stability of glucose-fructose oxidoreductase of cethyltrimethylammoniumbromide (CT AB) treated cells, the long term continuous process was carried out with Z. mobilis immobilized in K-carrageenan in the continuous stirred tank reactor(CSTR) and the packed bed reactor. The continuous production of sorbitol with the immobilized CT AB permeabilized cells in packed bed reactor was more stable than in CSTR. Two stage continuous process with CT AB treated cells of Z. mobilis immobilized in K-carrageenan was carried out at various dilution rates. At the first stage, the productivity was increased up to 15 g/ $\ell$ -h as dilution rate increased and decreased over 0.32$h^{-1}$ of dilution rate. Similarly, maximum productivity obtained at the second stage was 22g/$\ell$ -h at 0.32$h^{-1}$

K-carrageenan에 고정화시킨 Zymomonas mobilis를 이용한 연속적인 sorbitol 생산에 대하여 연구하였다. Toluene과 glutaraldehyde로 처리하여 투과성을 증대시킨 세포를 alginate나 chitin 고정화 공정에서 어느 정도의 효소활성을 보였으나 210시간 이상의 공정반응에서는 sorbitol 생성량이 감소되었다. 독성이 적고 투과성을 증가시키는 물질로서 toluene 대신 CTAB(Cetyltrimethylammoniumbromide)를 사용하였다. CTAB로 투과성을 증가시킨 세포를 k-carrageenan에 고정화하여 CSTR과 packed bed reactor를 이용하여 sorbitol 생산을 시도하였으며 CSTR보다도 (25일) packed bed reactor에서 (30일) 더 긴 시간 효소활성도가 유지되었다. Two-stage 연속공정에서는 희석비율이 (dilution rate, $h^{-1}$) 증가함에 따라서 sorbitol 생성률이 증가되었으며 희석비율 0.32 $h^{-1}$에서 첫번째와 두번째 반응조에서 각각 $15g/\ell-h,$ $22g/\ell-h의$ sorbitol 생성률을 얻었다. 0.32$h^{-1}$보다 높은 희석비율에서는 생성를이 감소되었다.