Production of L-Arabinose from Corn Hull Arabinoxylan by Arthrobacter aurescens MK5 α-L-Arabinofuranosidase

: Arabinoxylans, which are comprised of a xylan backbone to which are attached glycosyl units that are primarily L‐arabinofuranosyl units, are ubiquitous among plant species where it is a constituent of the cell wall. Arabinoxylan has attracted much attention as a potential biomass resource and L‐arabinose has recently been reported to possess functional properties that are effective in the treatment of diabetes. Here, we report an α‐L‐arabinofuranohydrolase, isolated from the soil microbe Arthrobacter aurescens strain MK5, effective in releasing L‐arabinose from corn hull arabinoxylan. When A. aurescens strain MK5 was grown in a liquid medium, corn hull arabinoxylan, which has a higher arabinose content (Ara/Xyl = 0.6) than oat spelts xylan (Ara/Xyl = 0.12), induced more efficient arabinoxylan hydrolase production. Analysis of enzyme activity in the culture broth revealed that arabinoxylan hydrolase activity was high, and α‐L‐arabinofuranosidase and β‐xylosidase activities were low. The optimum pH of the MK5 arabinoxylan hydrolase at 40 °C was around 7 and enzyme activity was relatively stable at an alkaline pH up to 9.5. The optimum temperature at pH 7 was around 50 °C and enzyme activity was stable under 50 °C. During the hydrolysis of corn hull arabinoxylan, only L‐arabinose was released and 45.1% maximum sugar recovery was achieved. The A. aurescens MK5 enzyme was a typical arabinoxylan α‐L‐arabinofuranohydrolase and was most effective at releasing L‐arabinose from corn hull arabinoxylan, which has a high arabinose content. This enzyme may have important industrial applications.