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<p>β-Glucosidases are in high demand for industrial processes such as lignocellulosic saccharification and high-salt food fermentation. However, conventional enzymes often lose activity under high-salt and alkaline conditions, which constrains their broader applicability. In this study, a glycoside hydrolase family 3 (GH3) β-glucosidase (designated PlGH3) was cloned from <i>Pontixanthobacter luteolus</i> SW-109, and was heterologously expressed in <i>Escherichia coli</i>, followed by systematic characterization of its enzymatic properties and structural simulation. PlGH3 showed an optimal pH of 9.0 and optimal temperature of 50&#xa0;°C, the kinetic parameters of PlGH3 toward <i>p</i>-nitrophenyl-β-D-glucopyranoside (<i>p</i>NPG) were determined as <i>K</i>ₘ = 0.63 mM and <i>V</i>ₘₐₓ = 3.00 U/mg. PlGH3 still maintained 40%-70% activity in alkaline environment for 24&#xa0;h. Ca²⁺, Mg²⁺, and Mn²⁺ improved its activity by 120%–140%. Notably, high salt strongly enhanced PlGH3’s activity, 4&#xa0;M NaCl increased enzyme activity by ~ 2.5-fold. It also exhibited ≥ 80% stability in most organic solvents and detergents. Local enrichment of acidic residues on the PlGH3 surface could generate a negative electrostatic potential, which enables adaptation to high-salt and alkaline environments, thereby sustaining the enzyme’s catalytic activity under such extreme conditions. Our study enriches marine extremophilic β-glucosidase resources and provides a promising candidate for high-salt/alkaline processes.</p>

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Characterization of a Novel GH3 β-Glucosidase with Alkali-Tolerant and Halophilic Properties from Pontixanthobacter luteolus SW-109

  • 期刊论文

  • 发表日期：

    2026年7月31日

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  • Kaijuan Wu,
  • Ke Guo,
  • Zheng Yu,
  • Liping Jiang,
  • Jing Huang

摘要

β-Glucosidases are in high demand for industrial processes such as lignocellulosic saccharification and high-salt food fermentation. However, conventional enzymes often lose activity under high-salt and alkaline conditions, which constrains their broader applicability. In this study, a glycoside hydrolase family 3 (GH3) β-glucosidase (designated PlGH3) was cloned from Pontixanthobacter luteolus SW-109, and was heterologously expressed in Escherichia coli, followed by systematic characterization of its enzymatic properties and structural simulation. PlGH3 showed an optimal pH of 9.0 and optimal temperature of 50 °C, the kinetic parameters of PlGH3 toward p-nitrophenyl-β-D-glucopyranoside (pNPG) were determined as Kₘ = 0.63 mM and Vₘₐₓ = 3.00 U/mg. PlGH3 still maintained 40%-70% activity in alkaline environment for 24 h. Ca²⁺, Mg²⁺, and Mn²⁺ improved its activity by 120%–140%. Notably, high salt strongly enhanced PlGH3’s activity, 4 M NaCl increased enzyme activity by ~ 2.5-fold. It also exhibited ≥ 80% stability in most organic solvents and detergents. Local enrichment of acidic residues on the PlGH3 surface could generate a negative electrostatic potential, which enables adaptation to high-salt and alkaline environments, thereby sustaining the enzyme’s catalytic activity under such extreme conditions. Our study enriches marine extremophilic β-glucosidase resources and provides a promising candidate for high-salt/alkaline processes.