Jornal de Biorremediação e Biodegradação

Abstrato

Analyses using Cell Wall Glycan-directed Monoclonal Antibodies Reveal Xylan-degradation by Two Microbial Glycosyl Hydrolases in Cell Walls from Poplar and Switchgrass Biomass

Supriya Ratnaparkhe, Sivasankari Venkatachalam, Michael G Hahn and Sivakumar Pattathil

Plant biomass represents the major source for renewable bio-fuels. Cell walls constitute the major portion of plant biomass. The main challenge in sustainable production of ligno-cellulosic biofuel is overcoming the cell wall recalcitrance barrier. A number of cell wall components including lignin and hemicelluloses have been shown to contribute to this cell wall recalcitrance. Thus, removing or reducing the proportion of wall components that contribute to cell wall recalcitrance of ligno-cellulosic biomass is a key step in sustainable ligno-cellulosic biofuel production. We have demonstrated the use of a comprehensive array of cell wall glycan-directed monoclonal antibodies to study the hydrolytic activities of two xylan-degrading microbial glycosyl hydrolases, CjXyl10B (a representative member of the GH10 family) and NpXyl11A (a representative member of the GH11 family) on cell wall extracts and cell walls from poplar and switchgrass biomass. Depletion of xylan epitopes, as monitored by the antibodies, in base extracts generated from raw poplar and switchgrass biomass that are treated with CjXyl10B or NpXyl11A confirmed the xylanase activity of these hydrolases, and demonstrates the utility of the antibody-based approach for screening for enzymes active on native biomass. Base extracts isolated from raw biomass treated with these enzymes prior to extraction also exhibited reduced xylan content. Further, prior removal of lignin significantly increased the efficiency of the xylan degradation in raw poplar and switchgrass biomass by the CjXyl10B and NpXyl11A enzymes. These results, thus hint that these two xylanases could potentially be used, in combination with lignin reduction, as efficient xylan-removing agents, while processing poplar and switchgrass feed stocks for biofuel production.