Enrichment of maize and triticale bran with recombinant Aspergillus tubingensis ferulic acid esterase

摘要

Ferulic acid is a natural antioxidant found invarious plants and serves as a precursor for various finechemicals, including the flavouring agent vanillin. However,expensive extraction methods have limited the commercialapplication of ferulic acid, in particular for theenrichment of food substrates. A recombinant Aspergillustubingensis ferulic acid esterase Type A (FAEA) wasexpressed in Aspergillus niger D15#26 and purified withanion-exchange chromatography (3487 U/mg, Km =0.43 mM, Kcat = 0.48/min on methyl ferulate). The36-kDa AtFAEA protein showed maximum ferulic acidesterase activity at 50 C and pH 6, suggesting potentialapplication in industrial processes. A crude AtFAEApreparation extracted 26.56 and 8.86 mg/g ferulic acidfrom maize bran and triticale bran, respectively, and alsosignificantly increased the levels of p-coumaric and caffeicacid from triticale bran. The cost-effective production ofAtFAEA could therefore allow for the enrichment of bransgenerally used as food and fodder, or for the production offine chemicals (such as ferulic and p-coumaric acid) fromplant substrates. The potential for larger-scale productionof 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.