title: Characterization of dextran-producing Weissella strains isolated from sourdoughs and evidence of constitutive dextransucrase expression.
abstract: The study of exopolysaccharide production by heterofermentative sourdough lactic acid bacteria has shown that Weissella strains isolated from sourdoughs produce linear dextrans containing α-(1→6) glucose residues with few α-(1→3) linkages from sucrose. In this study, several dextran-producing strains, Weissella cibaria and Weissella confusa, isolated from sourdough, were characterized according to carbohydrate fermentation, repetitive element-PCR fingerprinting using (GTG)(5) primers and glucansucrase activity (soluble or cell-associated). This study reports, for the first time, the characterization of dextransucrase from Weissella strains using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in situ polymer production (after incubation with sucrose) from enzymatic fractions harvested from both sucrose and glucose culture media. Results demonstrate that dextransucrase activity was mainly soluble and associated with a constitutive 180-kDa protein. In addition, microsequencing of the active dextransucrase from W. cibaria LBAE-K39 allowed the design of specific primers that could detect the presence of glucansucrase encoding genes similar to GTFKg3 of Lactobacillus fermentum Kg3 and to DSRWC of W. cibaria CMU. This study hence indicates that sourdough Weissella strains synthesize original dextransucrase.
authors: Laboratoire de Biologie appliquée à l'Agroalimentaire et à l'Environnement, Institut Universitaire de Technologie, Université Paul Sabatier, Auch, France.
authors: Marie-Sophie
authors: MS
authors: Bounaix
authors: Hervé
authors: H
authors: Robert
authors: Valérie
authors: V
authors: Gabriel
authors: Sandrine
authors: S
authors: Morel
authors: Magali
authors: M
authors: Remaud-Siméon
authors: Bruno
authors: B
authors: Gabriel
authors: Catherine
authors: C
authors: Fontagné-Faucher
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001939:Bread / Q000382:microbiology*; D003911:Dextrans / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D058836:Weissella / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003911:Dextrans; D005964:Glucosyltransferases; C020025:dextransucrase