Abstract:
Ferulic acid is a natural antioxidant found in
various plants and serves as a precursor for various fine
chemicals, including the flavouring agent vanillin. However,
expensive extraction methods have limited the commercial
application of ferulic acid, in particular for the
enrichment of food substrates. A recombinant Aspergillus
tubingensis ferulic acid esterase Type A (FAEA) was
expressed in Aspergillus niger D15#26 and purified with
anion-exchange chromatography (3487 U/mg, Km =
0.43 mM, Kcat = 0.48/min on methyl ferulate). The
36-kDa AtFAEA protein showed maximum ferulic acid
esterase activity at 50 C and pH 6, suggesting potential
application in industrial processes. A crude AtFAEA
preparation extracted 26.56 and 8.86 mg/g ferulic acid
from maize bran and triticale bran, respectively, and also
significantly increased the levels of p-coumaric and caffeic
acid from triticale bran. The cost-effective production of
AtFAEA could therefore allow for the enrichment of brans
generally used as food and fodder, or for the production of
fine chemicals (such as ferulic and p-coumaric acid) from
plant substrates. The potential for larger-scale production
of AtFAEA was demonstrated with the A. niger D15[AtfaeA]
strain yielding a higher enzyme activity (185.14 vs.83.48 U/ml) and volumetric productivity (3.86 vs. 1.74 U/ml/h) in fed-batch than batch fermentation.
