APPLICATION OF THE MELLE-BOINOT PROCESS TO THE FERMENTATION OF XYLOSEBY PACHYSOLEN-TANNOPHILUS

The Melle-Boinot process (cell-recycle batch fermentation) was applied to the fermentation of xylose by two strains of the yeast Pachysolen tannophilus for periods of 31 days. This resulted in a significant inc rease in the ethanol yield and productivity from xylose by P. tannophi lus NCYC 614 but not by strain CBS 4045. Analysis of cells of strain N CYC 614 at the end of the process revealed an increased ability to tol erate exogenous ethanol, a characteristic that was lost in the absence of selection pressure. It is postulated that the increased yield of e thanol from xylose by P. tannophilus NCYC 614 is a product of enhanced ethanol tolerance together with increased efficiency of the fermentat ion process associated with the Melle-Boinot system.