초록
<P><B>Background</B></P><P>The organic acid producer <I>Aspergillus oryzae</I> and <I>Rhizopus delemar</I> 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.</P><P><B>Results</B></P><P>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 <I>A. oryzae.</I> This includes levoglucosan, glucose, galactose, mannose, arabinose, xylose, ribose, and cellobiose as well as cheap and easy available sugars, e.g., fructose and maltose. <I>A. oryzae</I> 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 (<I>Fagus sylvatica</I>) and <I>Miscanthus giganteus</I> were further analyzed as carbon source for cultivation and fermentation with <I>A. oryzae</I> for malic acid and <I>R. delemar</I> 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 <I>A. oryzae</I> and 16.2 ± 0.2 g/L fumaric acid with <I>R. delemar</I>.</P><P><B>Conclusions</B></P><P>We showed in this study that the range of convertible sugars for <I>A. oryzae</I> is even higher than known before. We approved the suitability of fiber/cellulose hydrolysate obtained from the organosolv process as carbon source for <I>A. oryzae</I> in shake flasks as well as in a small-scale bioreactor. The more challenging hemicellulose fraction of <I>F. sylvatica</I> was also positively evaluated for malic acid production with <I>A. oryzae</I>.</P>