Tuesday, April 20, 2010
11-63

Cellulase production using different streams of wheat grain and wheat straw based ethanol processes

Miklós Gyalai-Korpos1, Réka Mangel1, Zsolt Barta1, Pablo Alvira2, Dóra Dienes1, Mercedes Ballesteros2, and Kati Réczey1. (1) Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szt. Gellért tér 4, Budapest, 1111, Hungary, (2) Renewable Energies Division. Biomass Unit, CIEMAT, Avda. Complutense, 22, Madrid, 28040, Spain

Pretreatment as being a necessary step in the biomass-to-ethanol process must be evaluated in the aspect of by-product utilization as well. By-product of wheat straw steam explosion (210 ºC, 2.5 minutes), referred as liquid fraction (or hydrolyzate), arises after the separation from the solid pretreated biomass. It comprises valuable carbohydrates (mainly xylose in mono- and oligomeric form, 5.54 g/L and 34.10 g/L, respectively) but also compounds potentially toxic to microbes (mainly furfural, acetic acid and formic acid, 2.45 g/L, 7.13 g/L and 2.69 g/L, respectively).

The aim of our study was the utilization of this liquid fraction as carbon source for cellulase production by Trichoderma reesei RUT C30 in shake flask cultures. Other main components of the medium were distiller’s spent grain (wheat based), plus in the second series of experiments ground wheat grain with or without α-amylase treatment. Supplementing the liquid fraction with these substrates makes an excellent opportunity to integrate first and second generation ethanol production. Efficiency of the fermentations was assessed by activity measurements (FPA, ß-glucosidase) and hydrolysis tests using the produced enzymes in the hydrolysis of steam pretreated wheat straw.

Results of the first series where no grain was added showed that detoxification of the liquid fraction is needed, since without it no enzyme production was observed. Preliminary results imply that combination of the liquid fraction with wheat grain can create a medium which is appropriate for effective in-house enzyme production in an integrated wheat-based ethanol production plant.


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