title: Isolation of a solventogenic Clostridium sp. strain: fermentation of glycerol to n-butanol, analysis of the bcs operon region and its potential regulatory elements.
abstract: A new solventogenic bacterium, strain GT6, was isolated from standing water sediment. 16S-rRNA gene analysis revealed that GT6 belongs to the heterogeneous Clostridium tetanomorphum group of bacteria exhibiting 99% sequence identity with C. tetanomorphum 4474(T). GT6 can utilize a wide range of carbohydrate substrates including glucose, fructose, maltose, xylose and glycerol to produce mainly n-butanol without any acetone. Additional products of GT6 metabolism were ethanol, butyric acid, acetic acid, and trace amounts of 1,3-propanediol. Medium and substrate composition, and culture conditions such as pH and temperature influenced product formation. The major fermentation product from glycerol was n-butanol with a final concentration of up to 11.5 g/L. 3% (v/v) glycerol lead to a total solvent concentration of 14 g/L within 72 h. Growth was not inhibited by glycerol concentrations as high as 15% (v/v). The solventogenesis genes crt, bcd, etfA/B and hbd composing the bcs (butyryl-CoA synthesis) operon of C. tetanomorphum GT6 were sequenced. They occur in a genomic arrangement identical to those in other solventogenic clostridia. Furthermore, the sequence of a potential regulator gene highly similar to that of the NADH-sensing Rex family of regulatory genes was found upstream of the bcs operon. Potential binding sites for Rex have been identified in the promoter region of the bcs operon of solvent producing clostridia as well as upstream of other genes involved in NADH oxidation. This indicates a fundamental role of Rex in the regulation of fermentation products in anaerobic, and especially in solventogenic bacteria.
authors: Department of Microbiology, Technische Universität München, Emil-Ramann Str. 4, 85350 Freising Weihenstephan, Germany.
authors: J C
authors: JC
authors: Panitz
authors: Department of Microbiology, Technische Universität München, Emil-Ramann Str. 4, 85350 Freising Weihenstephan, Germany; Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow 123182, Russia.
authors: V V
authors: VV
authors: Zverlov
authors: Department of Microbiology, Technische Universität München, Emil-Ramann Str. 4, 85350 Freising Weihenstephan, Germany.
authors: V T T
authors: VT
authors: Pham
authors: Department of Microbiology, Technische Universität München, Emil-Ramann Str. 4, 85350 Freising Weihenstephan, Germany.
authors: S
authors: S
authors: Stürzl
authors: Chair of Chemistry of Biogenic Resources, Technische Universität München, Schulgasse 16, 94315 Straubing, Germany.
authors: D
authors: D
authors: Schieder
authors: Department of Microbiology, Technische Universität München, Emil-Ramann Str. 4, 85350 Freising Weihenstephan, Germany. Electronic address: wschwarz@wzw.tum.de.
authors: W H
authors: WH
authors: Schwarz
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D048012:Clostridium tetanomorphum / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005285:Fermentation; D019015:Geologic Sediments; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D009876:Operon; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D020001:1-Butanol; D005990:Glycerol
keywords: Butanol production; Clostridium tetanomorphum; Glycerol fermentation; NADH; Rex regulator; bcs operon