EVOLUTIONARY ENZYMES AND SEPARATION PROCESSES FOR IMPROVED BIOREFINING OF CROPS AND RESIDUES
Location: Bioproduct Chemistry and Engineering Research
Title: Cloning of Bacillus licheniformis xylanase gene and characterization of recombinant enzyme
Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 2008
Publication Date: August 9, 2008
Citation: Lee, C.C., Accinelli, R., Smith, M.R., Wagschal, K.C., Orts, W.J., Wong, D. 2008. Cloning of Bacillus licheniformis xylanase gene and characterization of recombinant enzyme. Current Microbiology. 57:301-305.
Interpretive Summary: Lignocellulosic biomass is considered a prime alternative to fossil fuels as a source for many of our fuel and chemical feedstock needs. After cellulose, hemicellulose comprises the largest fraction of biomass. Improved breakdown of hemicellulose is a key factor in maximizing biomass utilization. Hemicellulose is comprised primarily of xylan, a polymer of xylose residues. We cloned a gene that encode a xylanase enzyme which will degrade xylan. We biochemically characterized the enzyme and demonstrated it's ability to break down xylan under a variety of conditions.
Hemicellulose is a major component of lignocellulose biomass. Complete enzymatic degradation of this substrate requires several different activities, including xylanase. We isolated a strain of Bacillus licheniformis from a hot springs environment that exhibited xylanase activity. A gene encoding a xylanase enzyme, Xyn11, was cloned, and recombinant protein was expressed in an Escherichia coli host and biochemically characterized. The optimum activity of the enzyme was at pH 6 and 40-50oC. The enzyme was thermal stable up to 50oC. Against birch wood xylan, the enzyme had apparent Km of 6.7 mg/ml and Vmax of 379 micromol/min/mg.