Efficient Extraction of Ferulic Acid from Sugar Beet Pulp Using the Culture Supernatant of Penicillium chrysogenum

We found a microorganism, Penicillium chrysogenum 31B, that has high ability to release ferulic acid from sugar beet pulp. Approximately 85% of alkaline-extractable ferulic acid in sugar beet pulp could be released using the culture supernatant of P. chrysogenum 31B. However, the culture supernatant did not efficiently extract ferulic acid from wheat bran, peel of corn seed, or sugar-cane bagasse. A ferulic acid esterase (FAE-1) was purified from the culture filtrate of P. chrysogenum 31B. The molecular mass of the enzyme was determined to be 62 kDa by SDS-PAGE. Optimum conditions for enzyme activity were 50°C and pH 6-7. The enzyme showed activity towards methyl esters of hydroxycinnamic acids including ferulic acid, p-coumaric acid, and caffeic acid, but was not active on methyl sinapinate or 3,4-dimethoxy cinnamate. The lack of activity of FAE-1 toward these substrates appears to be due to the presence of two methoxy groups on the benzene ring. The substrate specificity of FAE-1 seemed to be similar to that of ferulic acid esterase (CinnAE) of Aspergillus niger. However, there was a difference between FAE-1 and CinnAE in respect to activity towards methyl vanillate. It is remarkable that FAE-1 hydrolyzed methyl vanillate, which, to our knowledge, is the first report of a ferulic acid esterase hydrolyzing a hydroxybenzoic acid methyl ester.