Enzyme system of Clostridium stercorarium for hydrolysis of arabinoxylan: reconstitution of the in vivo system from recombinant enzymes

Abstract

Four extracellular enzymes of the thermophilic bacterium Clostridium stercorarium are involved in the depolymerization of de-esterified arabinoxylan: Xyn11A, Xyn10C, Bxl3B, and Arf51B. They were identified in a collection of eight clones producing enzymes hydrolysing xylan (xynA, xynB, xynC), b-xyloside (bxlA, bxlB, bglZ) and a-arabinofuranoside (arfA, arfB). The modular enzymes Xyn11A and Xyn10C represent the major xylanases in the culture supernatant of C. stercorarium. Both hydrolyse arabinoxylan in an endo-type mode, but differ in the pattern of the oligosaccharides produced. Of the glycosidases, Bxl3B degrades xylobiose and xylooligosaccharides to xylose, and Arf51B is able to release arabinose residues from de-esterified arabinoxylan and from the oligosaccharides generated. The other glycosidases either did not attack or only marginally attacked these oligosaccharides. Significantly more xylanase and xylosidase activity was produced during growth on xylose and xylan. This is believed to be the first time that, in a single thermophilic micro-organism, the complete set of enzymes (as well as the respective genes) to completely hydrolyse de-esterified arabinoxylan to its monomeric sugar constituents, xylose and arabinose, has been identified and the enzymes produced in vivo. The active enzyme system was reconstituted in vitro from recombinant enzymes.

Degradation of Wheat Straw by Fibrobacter succinogenes S85: a Liquid- and Solid-State Nuclear Magnetic Resonance Study

“…Incubations were carried out with labeled and unlabeled wheat straw, and samples were taken at various time intervals. After discarding the cell and straw pellets, we analyzed the culture medium by 1 Table 3. A large quantity of free xylose was identified, as well as free ␣-arabinopyranose and ␤-arabinopyranose.…”

Complete Cellulase System in the Marine Bacterium Saccharophagus degradans Strain 2-40 T

“…Because of its heterogeneity and complexity, plant cell wall degradation often requires a consortia of microorganisms (34,53). However, there are also cellulolytic organisms that have enzyme systems that act on hemicellulose components, e.g., certain members of the genus Clostridium (1,59).…”

Synergism of Glycoside Hydrolase Secretomes from Two Thermophilic Bacteria Cocultivated on Lignocellulose

“…Anaerobic thermophilic bacteria, primarily the clostridia, are excellent sources for hydrolytic enzymes able to decompose polysaccharides to fermentable sugars. There are several cellulose degraders in group I (6, 7) of the clostridia, including Clostridium thermocellum (8)(9)(10)(11)(12)(13)(14)(15), C. stercorarium (6,(16)(17)(18)(19)(20)(21), C. cellulosi (22), and C. aldrichii (23), which produce a wide range of hydrolases for polysaccharide degradation. The two most investigated species are C. thermocellum and C. stercorarium.…”