Influence of aeration on bioethanol production from ozonized wheat straw hydrolysates using Pichia stipitis
Bellido, C.; González-Benito, G.; Coca, M.ón.; Lucas, S.; García-Cubero, M.ía.T.
Bioresource Technology 133: 51-58
ISSN/ISBN: 1873-2976 PMID: 23422301 DOI: 10.1016/j.biortech.2013.01.104
The influence of aeration on ethanol production by Pichia stipitis was studied in wheat straw hydrolysates subjected to ozone pretreatment for the first time. In a first stage, different aeration rates ranging from 0.03 to 0.50 L air/min, which corresponds to a volumetric oxygen transfer coefficient from 1.1 to 9.6 h(-1), were applied to model glucose/xylose substrates. The most promising value was found to be 3.3 h(-1) (0.1 L air/min) leading to better xylose utilization, an ethanol yield of 0.40 g ethanol/g sugars and complete depletion of sugars at 72 h. In a second stage, the effect of aeration was analyzed in ozonized wheat straw hydrolysates. Sugars were completely depleted at 96 h and ethanol yield reached a value of 0.41 g ethanol/g sugars. The addition of controlled oxygen (K(L)a=3.8 h(-1)) enhances the efficiency of the process causing an increase of 29.1% in ethanol production and a considerable reduction of 42.9% in fermentation time as compared to non-aerated hydrolysates.