Preliminary research indicated that oscillations of residual glucose, ethanol and biomass were effectively attenuated after the tubular bioreactors were packed with wood chips, and the corresponding mechanism was speculated to be due to cell immobilization, micro-environmental change, and change in dilution rate.In this work, the change in dilution rate was excluded from the main reason for the oscillation attenuation.Through the comparison with the performance of the tubular bioreactors packed with polyurethane particles, Raschig rings and glass beads, it was found not only high biomass concentration resulted from cell immobilization, but also most importantly, the high yeast cell viability achieved in the system packing with wood chips effectively attenuated the oscillations.Further investigation revealed that the ethanol tolerance of yeast cells in the wood chip packing system was improved compared with that in non-packed system, which might further contribute to the oscillation attenuation.
