Metagenomic glycosyl hydrolases from the Amazon soil and goat rumen

High price and low efficiency of enzymes that deconstruct plant biomass are still major barriers for the economic viability of second generation bioethanol. Commercially available enzyme cocktails have not been specifically optimized for the most commonly used biomasses and pretreatments used in Brazil. To complement ongoing efforts based on traditional cultivation techniques of microorganisms, we have used a metagenomic approach to identify new glycosyl hydrolases from the Amazon soil and the goat rumen. Three metagenomic libraries were constructed and functionally screened for various activities such as endoglucanase, β-glucosidase, cellobiohydrolase and xylanase. A total of 343 clones with activity on CMC were identified. Seventy four clones with activity on CMC also displayed activity on xylan. It is not presently known if these results are due to a single protein with multiple activities or different genes on the same fragment. Bioinformatics analysis of the sequenced clones shows that for approximately half of these there are no identifiable glycosyl hydrolases, highlighting the importance of functional screens to identify new enzymes active on carbohydrates. Biochemical characterization of some selected metagenome enzymes is under way and will be presented.