Purification and characterization of a novel thermostable α-L-arabinofuranosidase from a color-variant strain of Aureobasidium pullulans.

摘要: More than one billion gallons of ethanol are produced annually in the United States, with approximately 95% it being derived from fermentation corn starch (4). Various lignocellulosic agricultural residues such as fiber, stover, straw, and bagasse can also serve low-value abundant feedstocks for production fuel alcohol. Currently, utilization biomass to produce faces significant technical economic challenges, its success depends largely on development highly efficient cost-effective enzymes conversion pretreated fermentable sugars. Hemicelluloses, second most common polysaccharides nature, represent about 20 35% (38). l-Arabinosyl widely distributed hemicelluloses they constitute monomeric and/or oligomeric side chains β-(1→4)-linked xylose or galactose backbones xylans, arabinoxylans, arabinogalactans core arabinans forming α-(1→5) linkages (26, 36). These restrict enzymatic hydrolysis by xylanases (2). α-l-Arabinofuranosidases (α-l-arabinofuranoside arabinofuranohydrolase, EC 3.2.1.55) (α-l-AFase) exo-type which hydrolyze terminal nonreducing α-l-arabinofuranosyl groups l-arabinose-containing polysaccharides. (1→3)- (1→5)-α-l-arabinofuranosyl arabinan both. The α-l-AFases part microbial xylanolytic systems required complete breakdown heteroxylans (2, 9, 22, 27). In recent years, arabinofuranosidases have received much attention because their practical applications various agro-industrial processes hemicellulosic fuels chemicals, delignification pulp, plant materials animal feed, grape monoterpenyl glycosides during wine (3, 8, 10, 35). There is a need develop suitable α-l-AFase use hemicellulose sugars subsequent other value-added chemicals. several bacteria fungi, but only few these been purified characterized (8, 11, 13, 33). color-variant strains yeast-like fungus Aureobasidium pullulans recognized excellent producers amylases, xylanase, β-glucosidase (20, 30, 31). differentiated typically pigmented (off-white black appearance) A. brilliant pigments red, yellow, pink, purple low DNA relatedness (21, 37). We found that strain an extracellular thermostable was able both (1→3) (1→5) arabinan. In this paper, we report purification characteristics novel enzyme.