Fachbereich Maschinenbauund

Verfahrenstechnik

67,1%

26,3%

6,4% 0,2%Succinic Acid

Acet Acid

Formic Acid

Fumaric Acid

Production of Dicarboxylic Acids from Beech Wood Hydrolysates

http://www.mv.uni-kl.de/biovt/

T. Sieker, J. Bosch, A. Duwe, N. Tippkötter, R. Ulber

University of Kaiserslautern, Institute of Bioprocess Engineering, Gottlieb-Daimler-Straße 44, 67663 Kaiserslautern

1. Introduction

The itaconic acid production by Aspergillus terreus is known to be very sensitive against a wide range of inhibitors, including several salt ions. Due to this, nei-ther growth nor itaconic acid formation could be ob-served when fermenting the untreated beech wood hydrolsate. For the detoxification of the hydrolysates a combination of anion- and cation exchangers in their H+ and OH--forms is very efficient. Hydrolysates in different concentrations were pre-pared (H1: 100 g

pulp L-1, H2 & 3: 300 g

pulp L-1), detoxified

(H1 & 2: 0.2 gadsorber

mL-1, H3: 0.4 gadsorber

mL-1) and tested for itaconic acid formation (see figure 1). Ita-conic acid yields of 0.25 g g-1 (H1 & H2) and 0.47 g g-1 (H3) could be achieved from the hydrolysates based on the consumed substrates.

Fermentable sugars derived from wooden celluloses and hemicelluloses by enzymatic hydrolysis are a promising renewable feedstock for the chemical industry. Although the fermentation of these sugars to ethanol has often been shown in literature, the production of higher value-added products from hydroly-sates is often difficult and has to be examined in more detail. Examples for such products are itaconic and succinic acid. As part of the German lignocellulose biorefinery project their production from technical beech wood hydrolysates is presented.

2. Itaconic Acid Production

Support Code: 22019409

Figure 1: Itaconic acid formation (top) and monosaccharide consumption (bottom) during fermentations on detoxified hy-drolysates.

3. Succinic Acid Production

For the succinic acid production Actinobacillus succi-nogenes is used. In contrast to Aspergillus terreus, it grows well and produces succinic acid even on the untreated hydrolysates, requiring CO

2 as further sub-

strate. Glucose and Xylose are completely consumed and succinic acid is formed as the major product with a yield of 0.7 g g-1 at a productivity of 0.39 g L-1 h-1.

4. Conclusions and Outlook

Itaconic and succinic acid production using techni-cal beech wood hydrolysates have been implement-ed at high yields. Future work will focus on the use of hydrolysates with higher monosaccharide concen-trations to reach higher product concentrations and on the purification of the acids.

0 20 40 60 800

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Conc

entra

tion [

g L-1]

Gluc

ose,

Xylos

e, Su

ccini

c acid

Cultivation time [h]

Figure 2: Succinic acid formation on beech wood hydrolysate.

Figure 3: Product distribution.

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-1]

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