Sustainable carbon sources for microbial organic acid production with filamentous fungi

Biotechnology for Biofuels

Thomas Hahn¹  Susanne Zibek¹  Katrin Ochsenreither²  Stefan Dörsam²  Jana Fesseler²  Olga Gorte²  Christoph Syldatk² 

[1] Industrial Biotechnology, Department of Molecular Biotechnology, Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB);Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology (KIT);

关键词: Aspergillus oryzae;    Rhizopus delemar;    Malic acid;    Malate;    Fermentation;    Organic acid;   

DOI  :  10.1186/s13068-017-0930-x

来源: DOAJ

【 摘 要 】

Abstract Background The organic acid producer Aspergillus oryzae and Rhizopus delemar are able to convert several alternative carbon sources to malic and fumaric acid. Thus, carbohydrate hydrolysates from lignocellulose separation are likely suitable as substrate for organic acid production with these fungi. Results Before lignocellulose hydrolysate fractions were tested as substrates, experiments with several mono- and disaccharides, possibly present in pretreated biomass, were conducted for their suitability for malic acid production with A. oryzae. This includes levoglucosan, glucose, galactose, mannose, arabinose, xylose, ribose, and cellobiose as well as cheap and easy available sugars, e.g., fructose and maltose. A. oryzae is able to convert every sugar investigated to malate, albeit with different yields. Based on the promising results from the pure sugar conversion experiments, fractions of the organosolv process from beechwood (Fagus sylvatica) and Miscanthus giganteus were further analyzed as carbon source for cultivation and fermentation with A. oryzae for malic acid and R. delemar for fumaric acid production. The highest malic acid concentration of 37.9 ± 2.6 g/L could be reached using beechwood cellulose fraction as carbon source in bioreactor fermentation with A. oryzae and 16.2 ± 0.2 g/L fumaric acid with R. delemar. Conclusions We showed in this study that the range of convertible sugars for A. oryzae is even higher than known before. We approved the suitability of fiber/cellulose hydrolysate obtained from the organosolv process as carbon source for A. oryzae in shake flasks as well as in a small-scale bioreactor. The more challenging hemicellulose fraction of F. sylvatica was also positively evaluated for malic acid production with A. oryzae.

【 授权许可】

Unknown