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Title: Isolation of alpha-glucuronidase enzyme from a rumen metagenomic library

item Lee, Charles
item Kibblewhite, Rena
item Wagschal, Kurt
item LI, RUPING - Three Gorges University
item Orts, William

Submitted to: Protein Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2011
Publication Date: 2/15/2012
Citation: Lee, C.C., Kibblewhite, R.E., Wagschal, K.C., Li, R., Orts, W.J. 2012. Isolation of alpha-glucuronidase enzyme from a rumen metagenomic library. Protein Journal. 31(3):206-211.

Interpretive Summary: Hemicellulose comprises a large percentage of the world’s biomass. As such, this material represents a rich source of renewable material for the chemical and fuel industries. In order to fully reduce this substrate into simpler components that can then be fermented to value-added products, a cocktail of various enzymes is required. One of the most important of these enzymes is alpha-glucuronidase (AG). There are relatively few examples of AG enzymes, and they are all derived from pure culture isolates. The vast library of potential genes found in the mixed populations of environmental microorganisms has not been a source of AG enzymes because of the lack of an appropriate discovery tool. In this report, we describe utilizing a novel assay to discover the first AG enzyme from a mixed microbial population. The new AG dramatically increases the efficiency of hemicellulose degradation in conjunction with other enzymes.

Technical Abstract: Alpha-Glucuronidase enzymes play an essential role in the full enzymatic hydrolysis of hemicellulose. Up to this point, all genes encoding alpha-glucuronidase enzymes have been cloned from individual, pure culture strains. Using a high-throughput screening strategy, we have isolated the first Alpha-glucuronidase gene (rum630-AG) from a mixed population of microorganisms. The gene was subcloned into a prokaryotic vector, and the enzyme was overexpressed and biochemically characterized. The RUM630-AG enzyme had optimum activity at 40oC. When birchwood xylan was used as substrate, the RUM630-AG functioned synergistically with an endoxylanase enzyme to hydrolyze the substrate.