Biomass production by a thermotolerant yeast: Hansenula polymorpha

Biomass production at high temperature by Hansenula polymorpha as part of a lignocellulosic utilizing process was studied. Compromise growth conditions (45 degrees C and pH = 4.8) with an eventual saccharification step were established. The effects of stirring rate and initial glucose concentration on biomass yield coefficient, volumetric productivity and maximal cell density were determined. Process optimization led to a fed-batch fermentation process: high yield (0.63 g dry cell g-1 glucose), volumetric productivity (1.3 g dry cell dm-3 h-1) and cell concentration (60 g dry cell dm-3) were obtained. At these conditions, significant arabitol excretion (18 g dm-3) as a unique by-product associated with cell mass production was obtained, making more interesting a high temperature operating process.