Synergistic production of l-arabinose from arabinan by the combined use of thermostable endo- and exo-arabinanases from Caldicellulosiruptor saccharolyticus

Abstract

The optimum conditions for the production of l-arabinose from debranched arabinan were determined to be pH 6.5, 75°C, 20gl−1 debranched arabinan, 42Uml−1 endo-1,5-α-l-arabinanase, and 14Uml−1 α-l-arabinofuranosidase from Caldicellulosiruptor saccharolyticus and the conditions for sugar beet arabinan were pH 6.0, 75°C, 20gl−1 sugar beet arabinan, 3Uml−1 endo-1,5-α-l-arabinanase, and 24Uml−1 α-l-arabinofuranosidase. Under the optimum conditions, 16gl−1l-arabinose was obtained from 20gl−1 debranched arabinan or sugar beet arabinan after 120min, with a hydrolysis yield of 80% and a productivity of 8gl−1h−1. This is the first reported trial for the production of l-arabinose from the hemicellulose arabinan by the combined use of endo- and exo-arabinanases.