title: Novel thermophilic hemicellulases for the conversion of lignocellulose for second generation biorefineries.
abstract: 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 α-glucuronidase from Alicyclobacillus acidocaldarius (GH10-XA and GH67-GA, respectively) and a α-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 °C (3.5 days). In addition, GH67-GC was the most stable α-glucuronidases from this family and the first able to hydrolyse both aldouronic acid and aryl-α-glucuronic acid substrates. These enzymes, led to the very efficient hydrolysis of beechwood xylan by using 7- to 9-fold less protein (concentrations <0.3 μM) and in much less reaction time (2h vs 12h) if compared to other known biotransformations catalyzed by thermophilic enzymes. In addition, remarkably, together with a thermophilic β-xylosidase, they catalyzed the production of xylose from the smart cooking pre-treated biomass of one of the most promising energy crops for second generation biorefineries. We demonstrated that search by the CAZy Data Bank of currently available genomes and detailed enzymatic characterization of recombinant enzymes allow the identification of glycoside hydrolases with novel and interesting properties and applications.
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: beatrice.cobucciponzano@ibbr.cnr.it.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Cobucci-Ponzano
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: andrea.strazzulli@ibbr.cnr.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Strazzulli
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: roberta.iacono@ibbr.cnr.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Iacono
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: giuseppe.masturzo@hotmail.com.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Masturzo
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: rosa.giglio@ibbr.cnr.it.
authors.forename: Rosa
authors.initials: R
authors.lastname: Giglio
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: mose.rossi@ibbr.cnr.it.
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Institute of Biosciences and Bioresources, National Research Council of Italy, Via P. Castellino 111, 80131 Naples, Italy. Electronic address: marco.moracci@ibbr.cnr.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Moracci
mesh_terms: D056450:Alicyclobacillus / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D056804:Biofuels / Q000032:analysis; D018533:Biomass; D001711:Biotransformation; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D000068536:Bacillota / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006358:Hot Temperature; D008031:Lignin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D056804:Biofuels; D011994:Recombinant Proteins; C036909:lignocellulose; D008031:Lignin; D006026:Glycoside Hydrolases; C023305:hemicellulase; C096734:alpha-glucuronidase; D043364:Endo-1,4-beta Xylanases
keywords: Biocatalysis; Bioconversion; Biofuel; Biotransformation; Thermophilic enzymes; White chemistry