An alkaline β-glucosidase isolated from an olive brine strain of Wickerhamomyces anomalus
2011
Restuccia, Cristina | Muccilli, Serena | Palmeri, Rosa | Randazzo, Cinzia L. | Caggia, Cinzia | Spagna, Giovanni
An efficient β-glucosidase (βG)-producing strain, Wickerhamomyces anomalus BS81, was isolated from naturally fermented olive brine and identified based on PCR/restriction fragment length polymorphism of the rDNA internal transcribed spacer and sequence analysis of the D1/D2 region of the 26S rRNA gene. The hydrolytic activity of the βG had an optimum pH of 8.5 and an optimum temperature of 35 °C. The enzyme had high substrate specificity and high catalytic efficiency (Km 0.99 mM, Vmax 14 U g⁻¹ of cells) for p-nitrophenyl-β-d-glucopyranoside. The enzyme was activated by increasing concentrations of NaCl, with maximum activity at 150 g L⁻¹ NaCl. Although βGs have been purified and characterized from several other sources, the W. anomalusβG is unique among βGs because its relative maximum activity occurs at alkaline pH and 35 °C. Moreover, the yeast strain has esterase activity that acts synergistically with βG to degrade oleuropein to debitter table olives and olive oil.
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