title: Substrate-induced production and secretion of cellulases by Clostridium acetobutylicum.
abstract: Clostridium acetobutylicum ATCC 824 is a solventogenic bacterium that grows heterotrophically on a variety of carbohydrates, including glucose, cellobiose, xylose, and lichenan, a linear polymer of beta-1,3- and beta-1,4-linked beta-D-glucose units. C. acetobutylicum does not degrade cellulose, although its genome sequence contains several cellulase-encoding genes and a complete cellulosome cluster of cellulosome genes. In the present study, we demonstrate that a low but significant level of induction of cellulase activity occurs during growth on xylose or lichenan. The celF gene, located in the cellulosome-like gene cluster and coding for a unique cellulase that belongs to glycoside hydrolase family 48, was cloned in Escherichia coli, and antibodies were raised against the overproduced CelF protein. A Western blot analysis suggested a possible catabolite repression by glucose or cellobiose and an up-regulation by lichenan or xylose of the extracellular production of CelF by C. acetobutylicum. Possible reasons for the apparent inability of C. acetobutylicum to degrade cellulose are discussed.
authors.affiliation: Laboratory of Microbiology, Wageningen University and Research Centre, P.O. Box 17, 6700 AA Wageningen, The Netherlands. ana.lopez-contreras@wur.nl
authors.forename: Ana M
authors.initials: AM
authors.lastname: López-Contreras
authors.forename: Krisztina
authors.initials: K
authors.lastname: Gabor
authors.forename: Aernout A
authors.initials: AA
authors.lastname: Martens
authors.forename: Bernadet A M
authors.initials: BA
authors.lastname: Renckens
authors.forename: Pieternel A M
authors.initials: PA
authors.lastname: Claassen
authors.forename: John
authors.initials: J
authors.lastname: Van Der Oost
authors.forename: Willem M
authors.initials: WM
authors.lastname: De Vos
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002480:Cellulase / Q000096:biosynthesis / Q000378:metabolism*; D003013:Clostridium / Q000201:enzymology*; D017931:DNA Primers; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; D002480:Cellulase