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Figure 1 | Biotechnology for Biofuels

Figure 1

From: Microbial β-glucosidases from cow rumen metagenome enhance the saccharification of lignocellulose in combination with commercial cellulase cocktail

Figure 1

pH (A) and temperature (B) optima and stability (C) of the purified β-glucosidases. The parameters were determined using p NPβG as the substrate. (A) The optimum pH was determined in the range of pH 4.0–8.5 at 40°C. The buffers (20 mM) used were as follows: acetate (pH 4.0-6.0), MES (pH 6.0-7.0), HEPES (pH 7.0-8.0) and Tris–HCl (pH 8.0-8.5). (B) For the optimum temperature determination, the pH was adjusted to 5.6 (sodium acetate 20 mM). In both cases, the kcat value was determined using an [enzyme] ranging from 0 to 12 nM and a substrate concentration of 70 mM. Activity at 100% refers to the kcat values described in Table 1. (C) The time lost normalised quantification of the β-glucosidase activity levels (with p NPβG) at conditions reassembling the supplementation assays (100 ml flasks with 12 g of pre-treated biomass and 5 g β-glucosidase solution at 25 U ml-1 (sodium acetate 20 mM), 50°C, pH 5.2; for details see Methods). For activity test at different time points, protein solution was separated from soil particles by ultrafiltration through low-adsorption hydrophilic 500000 NMWL cutoff membranes (regenerated cellulose, Amicon) and directly used for activity tests using p NPβG as the substrate. All measurements were analysed in triplicate as described in Methods. Error bars are not indicated because the standard deviation was lower than 5%.

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