title: Production of L-arabinose from corn hull arabinoxylan by Arthrobacter aurescens MK5 α-L-arabinofuranosidase.
abstract: 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.
authors.affiliation: Dept of Life and Nutritional Science, Fukuyama Univ, 1-985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292, Japan. kurakake@fubac.fukuyama-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurakake
authors.forename: Jyunpei
authors.initials: J
authors.lastname: Takao
authors.forename: Osamu
authors.initials: O
authors.lastname: Asano
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tanimoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Komaki
mesh_terms: D001089:Arabinose / Q000378:metabolism*; D001173:Arthrobacter / Q000201:enzymology*; D018554:Avena; D001426:Bacterial Proteins / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013379:Substrate Specificity; D013696:Temperature; D014990:Xylans / Q000737:chemistry*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D014990:Xylans; C085118:arabinoxylan; D001089:Arabinose; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase