A Versatile Family 3 Glycoside Hydrolase from Bifidobacterium adolescentis Hydrolyzes ?-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-?-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 ?-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 ?-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 ?-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-?-d-glucosides of the trichothecenes deoxynivalenol (DON), nivalenol, and HT-2 toxin. A Km of 5.4 mM and a Vmax of 16 ?mol 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-?-glucosides in cereal samples.

SUBMITTER: Michlmayr H 

PROVIDER: S-EPMC4495206 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature