The biotransformation of lignocellulose biomasses into fermentable sugars is a very complex procedure including, as one of the most critical steps, the (hemi) cellulose hydrolysis by specific enzymatic cocktails. We explored here, the potential of stable glycoside hydrolases from thermophilic organisms, so far not used in commercial enzymatic preparations, for the conversion of glucuronoxylan, the major hemicellulose of several energy crops. Searches in the genomes of thermophilic bacteria led to the identification, efficient production, and detailed characterization of novel xylanase and a-glucuronidase from Alicyclobacillus acidocaldarius (G1-110-XA and GH67-GA, respectively) and a alpha-glucuronidase from Caldicellulosiruptor saccharolyticus (GH67-GC). Remarkably, GH10-XA, if compared to other thermophilic xylanases from this family, coupled good specificity on beechwood xylan and the best stability at 65 degrees C (3.5 days). In addition, GH67-GC was the most stable alpha-glucuronidases from this family and the first able to hydrolyse both aldouronic acid and aryl-alpha-glucuronic acid substrates. These enzymes, led to the very efficient hydrolysis of beechwood xylan by using 7- to 9-fold less protein (concentrations
