|LIAO, HANS - Opx Biotechnologies, Inc|
|ZIDWICK, MARYJO - Cargill Corporation|
Submitted to: Journal of Industrial Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2013
Publication Date: 2/14/2013
Citation: Wong, D., Chan, V.J., Liao, H., Zidwick, M. 2013. Cloning of a novel feruloyl esterase gene from rumen microbial metagenome and enzyme characterization in synergism with endoxylanases. Journal of Industrial Microbiology. 40:287-295.
Interpretive Summary: Ferulic acid crosslinking plant cell wall biopolymers is a major cause of recalcitrance of biomass materials. The removal of ferulic acid crosslinks will increase the digestibility of lignocellulose and enzyme conversion to sugars as feedstock for biofuels and bioproducts. This report describes isolation, cloning, and expression of a novel gene of a ferulic acid esterase from rumen microbes. The properties of the enzyme were extensively chracterized. Its synergistic effect with xylanases which attack the main chain of hemicellulose was found to significantly increase the release of ferulic acid from a variety of natural biomass substrates. This will lead to high-efficiency breakdown rendering the cell wall polysaccharides more accessible for complete degradation.
Technical Abstract: A feruloyl esterase (FAE) gene was isolated from a rumen microbial metagenome, cloned into E. coli, and expressed in active form. The enzyme (RuFae2) was identified as a Type C feruloyl esterase, which acted on methyl ferulate, methyl p-coumarate, methyl sinapinate, methyl caffeate, but not diferulate. The RuFae2 alone released ferulic acid from rice bran, wheat bran, wheat insoluble arabinoxylan, corn fiber, switchgrass, and corn bran in the order of decreasing activity. Using a saturating amount of RuFae2 for 100 mg substrate, a maximum of 18.7 mg and 80.0 mg FA was released from 100 mg corn fiber and wheat insoluble arabinoxylan, respectively. Addition of GH10 endoxylanase (EX) synergistically increased the release of FA with the highest level of 6.7 fold for wheat bran. The synergistic effect of adding GH11 EX was significantly smaller with all the substrates tested. The difference in the effect of the two EXs was further analyzed by comparing the rate in the release of FA with increasing EX concentration using wheat insoluble arabinoxylan as the substrate.