title: A Versatile Family 3 Glycoside Hydrolase from Bifidobacterium adolescentis Hydrolyzes β-Glucosides of the Fusarium Mycotoxins Deoxynivalenol, Nivalenol, and HT-2 Toxin in Cereal Matrices.
abstract: Glycosylation plays a central role in plant defense against xenobiotics, including mycotoxins. Glucoconjugates of Fusarium toxins, such as deoxynivalenol-3-O-β-d-glucoside (DON-3G), often cooccur with their parental toxins in cereal-based food and feed. To date, only limited information exists on the occurrence of glucosylated mycotoxins and their toxicological relevance. Due to a lack of analytical standards and the requirement of high-end analytical instrumentation for their direct determination, hydrolytic cleavage of β-glucosides followed by analysis of the released parental toxins has been proposed as an indirect determination approach. This study compares the abilities of several fungal and recombinant bacterial β-glucosidases to hydrolyze the model analyte DON-3G. Furthermore, substrate specificities of two fungal and two bacterial (Lactobacillus brevis and Bifidobacterium adolescentis) glycoside hydrolase family 3 β-glucosidases were evaluated on a broader range of substrates. The purified recombinant enzyme from B. adolescentis (BaBgl) displayed high flexibility in substrate specificity and exerted the highest hydrolytic activity toward 3-O-β-d-glucosides of the trichothecenes deoxynivalenol (DON), nivalenol, and HT-2 toxin. A Km of 5.4 mM and a Vmax of 16 μmol min(-1) mg(-1) were determined with DON-3G. Due to low product inhibition (DON and glucose) and sufficient activity in several extracts of cereal matrices, this enzyme has the potential to be used for indirect analyses of trichothecene-β-glucosides in cereal samples.
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria herbert.michlmayr@boku.ac.at.
authors.forename: Herbert
authors.initials: H
authors.lastname: Michlmayr
authors.affiliation: Christian Doppler Laboratory for Mycotoxin Metabolism and Center of Analytical Chemistry, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Varga
authors.affiliation: Christian Doppler Laboratory for Mycotoxin Metabolism and Center of Analytical Chemistry, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Malachova
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria.
authors.forename: Nhung Thi
authors.initials: NT
authors.lastname: Nguyen
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria.
authors.forename: Cindy
authors.initials: C
authors.lastname: Lorenz
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, University of Natural Resources and Life Sciences, Vienna (BOKU), Vienna, Austria.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Haltrich
authors.affiliation: Christian Doppler Laboratory for Mycotoxin Metabolism and Center of Analytical Chemistry, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Berthiller
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
mesh_terms: D001644:Bifidobacterium / Q000201:enzymology*; D044602:Cellulases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002523:Edible Grain / Q000737:chemistry; D005670:Fusarium / Q000378:metabolism*; D005960:Glucosides / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D052196:Levilactobacillus brevis / Q000201:enzymology; D009183:Mycotoxins / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D013605:T-2 Toxin / Q000031:analogs & derivatives* / Q000378:metabolism; D014255:Trichothecenes / Q000378:metabolism*
chemical_list: D005960:Glucosides; D009183:Mycotoxins; D011994:Recombinant Proteins; D014255:Trichothecenes; C038405:nivalenol; D044602:Cellulases; D013605:T-2 Toxin; C007262:deoxynivalenol; C012351:HT-2 toxin