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United States Department of Agriculture

Agricultural Research Service

Research Project: FUNGAL RESOURCES FOR BIOLOGICAL CONTROL AND HIGH-VALUE USES

Location: Biological Integrated Pest Management Unit

Title: Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi

Authors
item King, B. -
item Waxman,, K. -
item Nenni,, N. -
item Walker,, L. -
item Bergstrom, G. -
item Gibson, Donna

Submitted to: Biotechnology for Biofuels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2011
Publication Date: February 16, 2011
Citation: King, B.C., Waxman,, K.D., Nenni,, N.V., Walker,, L.P., Bergstrom, G.C., Gibson, D.M. 2011. Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi. Biotechnology for Biofuels. 4:4.

Interpretive Summary: Breakdown of plant cell walls to fermentable sugars is a critical step in the conversion process to bioethanol. The most effective means of breakdown uses a cocktail of different cellulose-degrading enzymes, but conversion is still not optimal so there is a need to identify enzymes to enhance the breakdown process. In this study, we surveyed a broad range of plant pathogenic and nonpathogenic fungi for their ability to degrade plant biomass and isolated polysaccharides. Among moderately and highly active species, plant pathogenic species were more active than non-pathogens on six of eight substrates tested, and greater hydrolysis was seen when tested on biomass derived from their host plants (monocot or dicot). This analysis should prove useful in identifying new sources of novel enzymes for biofuel production.

Technical Abstract: Discovery and development of novel plant cell wall degrading enzymes is a key step towards more efficient depolymerization of polysaccharides to fermentable sugars for production of liquid transportation biofuels and other bioproducts. The industrial fungus Trichoderma reesei is known to be highly cellulolytic and is a major industrial microbial source for commercial cellulases, xylanases, and other cell wall degrading enzymes. However, enzyme-prospecting research continues to identify opportunities to enhance the activity of T. reesei enzyme preparations by supplementing with enzymatic diversity from other microbes. The goal of this study was to evaluate the enzymatic potential of a broad range of plant pathogenic and non-pathogenic fungi for their ability to degrade plant biomass and isolated polysaccharides. Large-scale screening identified a range of hydrolytic activities among 348 unique isolates representing 156 species of plant pathogenic and non-pathogenic fungi. Hierarchical clustering was used to identify groups of species with similar hydrolytic profiles. Among moderately and highly active species, plant pathogenic species were more active than non-pathogens on six of eight substrates tested, with no significant difference seen on the other two substrates. Among pathogenic fungi, greater hydrolysis was seen when tested on biomass and hemicellulose derived from their host plants (commelinoid monocot or dicot). These highly active fungi are promising targets for further identification and characterization of novel cell wall degrading enzymes for industrial applications.

Last Modified: 11/24/2014