High-value bioproducts from biomass is important to off-set the cost of second-generation biofuels. For instance, biopolymers with increased surface hydrophobicity or reactivity could increase their performance in plastic-displacing materials and biocomposites. However, the extensive representation of hydroxyl functional groups on biomass-derived polysaccharides complicates reproducible alteration of these polymers using chemical catalysts. By contrast, microbial enzymes have evolved to specifically target precise positions on these polysaccharides and catalyze stereospecific reactions. Over 170 putative lipase and esterase encoding genes from more than 15 microorganisms were expressed in Escherichia coli. Functionally expressed enzymes will be evaluated for ability to catalyze the transesterification of hemicellulose and phenolic or aliphatic compounds. Here, biochemical data for two novel esterases are reported. SAV_Est1 and RP_Est1 from Streptomyces avermitilis and Rhodopseudomonas palustris, respectively, were cloned from the corresponding genomes, and purified using affinity chromatography. While RP_Est1 hydrolyzed substrates ranging from p-nitrophenyl (pNP)-acetate to pNP-palmitate and pNP benzoate, SAV_Est1 hydrolyzed pNP-acetate and pNP-benzoate. RP_Est1 also hydrolyzed olive oil. These date suggest that RP_Est1 is a lipase, whereas SAV_Est1 is an aryl esterase. The optimum pH for SAVest1 and RPest1 was 8 and 7, respectively. SAVest1 was stable from pH 7 to pH 10 whereas RPest1 is stable from pH 4 to pH 9. The half life of SAVest1 and RPest1 at 50°C is 2 h and 5 h, respectively. Both enzymes exhibited stability in the present of detergents, organic solvents, and ionic liquids. These data will be used to develop optimal reaction conditions for transesterification of biomass-derived hemicellulose.