Ferulic Acid Esterase Activities of Typical Intestinal Bacteria

Ferulic acid esterase activity arose in the ceca of rats that were fed on acid hydrolysate of refined corn bran. The main component of this hydrolysate was soluble ferulic acid arabinoxylan ester. In order to determine the relationship between the ferulic acid esterase activity and intestinal bacteria, the ferulic acid esterase activities from the four kinds of typical bacteria in the intestine were measured. Ferulic acid arabinose ester (LMW) and ferulic acid arabinoxylan ester (HMW) were used as substrates. The enzyme from Lactobacillus acidophilus exhibited the highest activity when LMW was used as a substrate. However, when HMW was used, all enzymes from these bacteria exhibited trace activities. At the same time, Bifidobacterium bifidum showed high xylanase and arabinofuranosidase activities. It was suggested that the xylanase and the arabinofuranosidase from bacteria such as B. bifidum attacked HMW and degraded it to lower molecules at first. The ferulic acid esterase from bacteria such as L. acidophilus might then act to release ferulic acid in the cecum.