Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Nowadays, biochemical production of second generation bioethanol represents a promising option for energetic diversification in the transportation sector in the short-medium term. However, tridimensional structure of lignocellulosic materials limits the accessibility of cellulose to cellulolytic enzymes and thus, a pretreatment step to open up the structure of the lignocellulosic material is needed. Hydrothermal processes such as steam explosion are cost-effective and necessary technologies to enhance the accessibility of cellulose and the fermentable sugars recovery. In contrast, partial sugars and lignin degradation during pretreatment produces different toxic compounds that inhibit the subsequent enzymatic hydrolysis and fermentation steps. In this context, physical, chemical and biological treatments have been developed to remove these inhibitors. Most of these treatments were carried out using the liquor obtained after pretreatment; however, the detoxification of whole slurry has been less studied.
In this work, the use of laccases for the detoxification of whole slurry obtained after steam explosion of wheat straw was studied. As expected, the laccase treatment selectively removed phenolic compounds from the slurry. The detoxification ability of laccase was also evaluated in a simultaneous saccharification and fermentation (SSF) and in a prehydrolysis and simultaneous saccharification and fermentation (PSSF) processes with the thermotolerant yeast Kluyveromyces marxianus. Results showed that the decrease of phenolic content by laccase treatment make it possible to increase the consistency of substrate, to reduce lag phase of microorganism and to improve ethanol production.