Ethanol production from xylose with the yeastPichia stipitis and simultaneous product recovery by gas stripping using a gas-lift loop fermentor with attached side-arm (GLSA)

Abstract

The bioconversion of xylose into ethanol with the yeast Pichia stipitis CBS 5773 is inhibited when 20 g/L of ethanol are present in the fermentation broth. In order to avoid this limitation, the fermentation was carried out with simultaneous recovery of product by CO2 stripping. The fermentation was also improved by attaching a side‐arm to the main body of a classical gas‐lift loop fermentor. This side‐arm increases the liquid circulation, mass transfer, and gas distribution, reducing the amount of oxygen in the inlet gas necessary to perform the fermentation of xylose under microaerobic conditions (KLa ≊ 16 h−1). The continuous stripping of ethanol from the fermentation broth in this new bioreactor system allowed the consumption of higher xylose concentrations than using Erlenmeyer shaker flasks, improved significantly the process productivity and provided a clean ethanol solution by using an ice‐cooled condenser system. Finally, a fed‐batch fermentation was carried out with a KLa = 15.8 h−1. Starting with 248.2 g of xylose, 237.6 g of xylose was consumed to produce 88.1 g of ethanol which represents 72.6% of the theoretical yield (47.2 g/L of ethanol was recovered in the condenser, while 9.6 g/L remained in the fermentation broth). © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 67: 336–343, 2000.

Xylose reductase activity in Debaryomyces hansenii UFV-170 cultivated in semi-synthetic medium and cotton husk hemicellulose hydrolyzate

“…Unpublished results demonstrated that D. hansenii UFV-170 was able to utilize as the only carbon source either 50 g l -1 glycerol or ethanol (typical metabolic byproducts of its metabolism), with percentage consumptions of 17 and 37%, respectively, but the specific growth rate was high only with the former (l = 0.44 ± 0.01 h -1 ), due to the well-known inhibitory effect of ethanol on the metabolism of yeasts in general [27,29,30] and of D. hansenii in particular [31]. Therefore, we decided to check the ability of this microorganism to grow on xylitol, i.e., the main product of xylose-to-xylitol bioconversion.…”

Fermentation of acid hydrolysates from olive-tree pruning debris by Pachysolen tannophilus

“…With regard to the fermentation with P. tannophilus, different research groups have identified difficulties such as inhibition by ethanol [9] or by products of sugar degradation contained in the hydrolysate such as phenolic compounds, furan derivatives, and aliphatic acids [10].…”

Bioprospecting thermophilic/thermotolerant microbes for production of lignocellulosic ethanol: A future perspective

“…Hashi et al [91] studied the recovery of ethanol from carbon dioxide stripped vapor mixture and validated their results with a mathematical model to predict the adsorption performance of activated carbon WV-B 1500 for ethanol vapor adsorption in the presence of carbon dioxide and water. Dominguez et al [92] showed an improvement in circulation, mass transfer and gas distribution in fermentationstripping process by using a special gas-lift loop reactor with external side-arm for xylose to ethanol conversion. They used icecooled condenser for the product recovery.…”