Monday, May 5, 2008
7-30

Simultaneous saccharification and fermentation (SSF) of steam pretreated hemp

Zsófia Kádár1, Ignacio Ballesteros2, Jose M. Oliva2, Paloma Manzanares2, María J. Negro2, Nóra Szijártó1, Imre Nagy3, Kati Réczey1, and Mercedes Ballesteros2. (1) Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szt. Gellért tér 4., Budapest, 1111, Hungary, (2) Renewable Energies Department, CIEMAT, Avda. Complutense 22., Madrid, 28040, Spain, (3) Pólus Plus Co., Hunyadi János út 9., Budapest, 1117, Hungary

This work was focused on industrial hemp, which is rarely investigated as possible substrate for bioethanol production. Preliminary results, presented at the 29th Symposium, showed that even though enzymatic accessibility of the cellulose rich component in hemp was increased by chemical pretreatment, unfortunately the enzymatic conversion was stil rather low. According to these experiments a more effective pretreatment method (steam explosion) was adressed for further studies. The aim of the present work was to optimize this pretreatment method of hemp with a view on maximizing ethanol production by two different yeast strains.

Hemp was grown and harvested in Hungary in the fall of 2006. Steam explosion (SE) was carried out in a batch pilot plant according to a factorial design, where the effect of residence time, temperature and use of acid catalyst were investigated. Pretreated material (slurry) was separated into liquid (prehydrolysate) and solid fraction and analyzed for carbohydrates and toxic compounds.

Liquid fractions were used to test the effect of inhibitory compounds of steam pretreated hemp produced during pretreatment on Saccharomyces cerevisiae and Kluyveromyces marxianus CECT 10875. Fermentation of the SE solids was performed to determine the ethanol yield from the cellulose fraction of hemp by baker’s yeast.and K. marxianus. SSF was performed in 50 ml at 10 (w/v)% solid content at pH 5,0. Commercial enzymes at loading dosage of 25 FPU/g cellulose were applied. The flasks were incubated for 3 days at 32°C and 42°C, respectively. Results from this study will be presented and discussed at the conference.


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