Flame-burned stainless steel wire spheres as carriers of Zymomonas mobiliscells and extracellular levansucrase

In the present work, the use of flame-burned WS as carriers of Z. mobilis a nd extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and c onvective drying of Z. mobilis biomass at 30 degrees C to a moisture conten t of 10-14 % gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation betwe en the product formation and the concentration of free cells in the ferment ation medium was established. Clearly, the cells were weakly bound to the n ewly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented that components excreted from damaged cell s during dehydration can intensify the reactivation of damaged living cells and influence the interactions between the cells and the wire surface. The passive immobilization of extracellular levansucrase in oxidized WS was also observed. The superiority of oxidized WS in comparison with non-treat ed WS is related to an increase in the number of OH groups. The potential r egeneration of WS by burning after the termination of fermentation cycles w as also considered.