title: Regulation of the synthesis of pulp degrading enzymes in Bacillus isolated from cocoa fermentation.
abstract: Pectin degrading enzymes are essential for quality of product from cocoa fermentation. Previously, we studied purified pectate lyases (Pel) produced by Bacillus strains from fermenting cocoa and characterized the cloned pel genes. This study aims to search for biological signals that modulates Pel production and regulators that influence pel gene expression. Strains were grown to the end of exponential phase in media containing various carbon sources. Pel enzymes production in Bacillus was unaffected by simple sugar content variation up to 2%. Additionally, it appeared that pel gene is not under the control of the most common carbon and pectin catabolism regulators ccpA and kdgR, which could explain the insensitivity of Pel production to carbon source variation. However, a 6-fold decrease in Pel production was observed when bacteria were grown in LB rich medium as opposed to basal mineral medium. Subsequently, bioinformatics analysis of cloned pel gene promoter region revealed the presence of DegU binding site. Furthermore, the deletion of degU gene dramatically reduces the pel gene expression, as revealed by real time quantitative PCR, showing an activation effect of DegU on Pel synthesis in Bacillus strains studied. We assumed that, during the latter stage of cocoa fermentation when simple sugars are depleted, production of Pel in Bacillus is stimulated by DegU to supply microbial cells with carbon source from polymeric pectic compounds.
authors.affiliation: Laboratoire de Biotechnologies, UFR Biosciences, Université Félix Houphouet-Boigny Abidjan, 22 bp 582 Abidjan, Cote d'Ivoire; Univ Lyon, Université Lyon 1, INSA de Lyon, CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, 10 rue Raphaël Dubois, F-69622 Villeurbanne, France. Electronic address: kidou12@yahoo.fr.
authors.forename: Honoré G
authors.initials: HG
authors.lastname: Ouattara
authors.affiliation: Univ Lyon, Université Lyon 1, INSA de Lyon, CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, 10 rue Raphaël Dubois, F-69622 Villeurbanne, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Reverchon
authors.affiliation: Laboratoire de Biotechnologies, UFR Biosciences, Université Félix Houphouet-Boigny Abidjan, 22 bp 582 Abidjan, Cote d'Ivoire.
authors.forename: Sébastien L
authors.initials: SL
authors.lastname: Niamke
authors.affiliation: Univ Lyon, Université Lyon 1, INSA de Lyon, CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, 10 rue Raphaël Dubois, F-69622 Villeurbanne, France.
authors.forename: William
authors.initials: W
authors.lastname: Nasser
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000235:genetics; D002099:Cacao / Q000382:microbiology*; D002244:Carbon / Q000378:metabolism; D003001:Cloning, Molecular; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D010368:Pectins / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000096:biosynthesis / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; C066497:DegU protein, Bacteria; D002244:Carbon; D010368:Pectins; D011133:Polysaccharide-Lyases; C023911:pectate lyase
keywords: Bacillus; Cocoa fermentation; DegU regulator; Pectate lyase; pel gene regulation