| Summary: | A droplet-based microfluidic ultrahigh-throughput screening technology has been developed for the selection of high-β-xylosidase-producing <i>Penicillium piceum</i> W6 from the atmospheric and room-temperature plasma-mutated library of <i>P. piceum</i>. β-xylosidase hyperproducers filamentous fungi, <i>P. piceum</i> W6, exhibited an increase in β-xylosidase activity by 7.1-fold. A novel β-D-xylosidase was purified from the extracellular proteins of <i>P. piceum</i> W6 and designated as PpBXL. The optimal pH and temperature of PpBXL were 4.0 and 70 °C, respectively. PpBXL had high stability an acidic pH range of 3.0–5.0 and exhibited good thermostability with a thermal denaturation half-life of 10 days at 70 °C. Moreover, PpBXL showed the bifunctional activities of α-L-arabinofuranosidase and β-xylosidase. Supplementation with low-dose PpBXL (100 μg/g substrate) improved the yields of glucose and xylose generated from delignified biomass by 36–45%. The synergism between PpBXL and lignocellulolytic enzymes enhanced delignified biomass saccharification, increased the Xyl/Ara ratio, and decreased the strength of hydrogen bonds.
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