CONTRIBUTIONS OF IMMOBILIZED AND FREE-CELLS OF SALT-TOLERANT ZYGOSACCHAROMYCES-ROUXII AND CANDIDA-VERSATILIS TO THE PRODUCTION OF ETHANOL AND 4-ETHYLGUAIACOL

The contribution of immobilized cells and free cells released from gel beads to ethanol production by the salt-tolerant yeasts Zygosaccharomyces rouxii and Candida versatilis, and 4-ethylguaiacol (4-EG) production by C. versatilis were investigated using an airlift reactor. The amounts of ethanol produced by free cells were about 65% and about 90% of total ethanol in the reactor for Z. rouxii and C. versatilis, respectively. It was found that immobilized cells gave a much lower specific productivity of ethanol (ethanol production per hour per cell) than free cells of both yeasts, especially of C. versatilis. 4-EG was produced mainly by immobilized cells of C. versatilis; the amount of 4-EG produced by free cells was about 20% of the total 4-EG, in contrast to the results of ethanol production. However, the specific productivity of 4-EG (4-EG production per hour per cell) by immobilized and free cells was fairly similar. © 1990 Springer-Verlag.