Biochemical analyses of multiple endoxylanases from the rumen bacterium ruminococcus albus 8 and their synergistic activities with accessory hemicellulose-degrading enzymes

Young Hwan Moon, Michael Iakiviak, Stefan Bauer, Roderick I. Mackie, Isaac K.O. Cann

Research output: Contribution to journalArticle

Abstract

Ruminococcus albus 8 is a ruminal bacterium capable of metabolizing hemicellulose and cellulose, the major components of the plant cell wall. The enzymes that allow this bacterium to capture energy from the two polysaccharides, therefore, have potential application in plant cell wall depolymerization, a process critical to biofuel production. For this purpose, a partial genome sequence of R. albus 8 was generated. The genomic data depicted a bacterium endowed with multiple forms of plant cell wall-degrading enzymes. The endoxylanases of R. albus 8 exhibited diverse modular architectures, including incorporation of a catalytic module, a carbohydrate binding module, and a carbohydrate esterase module in a single polypeptide. The accessory enzymes of xylan degradation were a β-xylosidase, an α-L-arabinofuranosidase, and an β-glucuronidase. We hypothesized that due to the chemical complexity of the hemicellulose encountered in the rumen, the bacterium uses multiple endoxylanases, with subtle differences in substrate specificities, to attack the substrate, while the accessory enzymes hydrolyze the products to simple sugars for metabolism. To test this hypothesis, the genes encoding the predicted endoxylanases were expressed, and the proteins were biochemically characterized either alone or in combination with accessory enzymes. The different endoxylanase families exhibited different patterns of product release, with the family 11 endoxylanases releasing more products in synergy with the accessory enzymes from the more complex substrates. Aside from the insights into hemicellulose degradation by R. albus 8, this report should enhance our knowledge on designing effective enzyme cocktails for release of fermentable sugars in the biofuel industry.

Original languageEnglish (US)
Pages (from-to)5157-5169
Number of pages13
JournalApplied and environmental microbiology
Volume77
Issue number15
DOIs
StatePublished - Aug 2011

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Fingerprint Dive into the research topics of 'Biochemical analyses of multiple endoxylanases from the rumen bacterium ruminococcus albus 8 and their synergistic activities with accessory hemicellulose-degrading enzymes'. Together they form a unique fingerprint.

  • Cite this