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Pleurotus ferulae is a mushroom typically found in arid steppe that is distributed widely in the Junggar Basin of Xinjiang, China. In this work, laccase production by P. ferulae JM30X was optimized in terms of medium composition and culture conditions. After optimization, the highest laccase activity obtained was 6,832.86 U/L. A single isozyme with a molecular weight of 66 kDa was observed by SDS-PAGE and native-PAGE. Optimum pH and temperature were 3.0 and 50-70 °C, respectively. The best laccase substrate was ABTS, for which the Michaelis-Menten constant (K m ) and catalytic efficiency (K cat /K m ) value for P. ferulae laccase were 0.193 mM and 2.73×10 6 (mM s) −1 , respectively. The activity of purified laccase was increased by more than four-fold by Cu 2+ , Mn 2+ and Mg 2+ , while it was completely inhibited by Fe 2+ and Fe 3+ . The production of laccase was influenced by the initial pH and K + concentration, and the activity of purified laccase was enhanced by Cu 2+ , Mn 2+ and Mg 2+ . This Pleurotus genus laccase from P. ferulae JM30X was analyzed by MS spectrum and the results are conducive to furthering our understanding of Pleurotus genus laccases.

BACKGROUND Pea sprouts are considered a healthy food. Sucrose is a key nutritional factor affecting taste and flavor. Meanwhile, selenium (Se) is an essential micronutrient that plays multiple roles in wide variety of physiological processes and improves crop quality and nutritional value. Nonetheless, the effects of the combination of sucrose and Se treatment on growth, quality, and sugar metabolism of pea sprouts have not been explored. RESULTS The results revealed that sucrose at 10 mg L−1 obviously increased fresh weight, vitamin C, soluble protein, soluble sugar, fructose, glucose, and sucrose contents. Se treatments also improved nutritional quality, but higher Se (2.5 mg L−1) significantly inhibited the growth of seedlings. Interestingly, the combined application of sucrose (10 mg L−1) and Se (1.25 mg L−1) could effectively promote vitamin C, sucrose, and fructose contents, especially the Se content, compared with Se application alone. Additionally, there were significant differences in the regulation of sugar metabolism between Se alone and combined application of sucrose and Se. Acid invertase and neutral invertase play a pivotal role in the accumulation of soluble sugar under Se treatments alone, and acid invertase might be the key enzyme to limit sugar accumulation under combined application of sucrose and Se. CONCLUSION The moderate combined application of sucrose (10 mg L−1) and Se (1.25 mg L−1) more effectively regulated sugar metabolism and improved nutritional quality than Se application alone did. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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