Jiangxi Province Key Laboratory of Animal Nutrition/Engineering Research Center of Feed Development, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, China; College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, China.
College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, Jiangxi 330045, China.
Int J Biol Macromol. 2021 Feb 28;171:382-388. doi: 10.1016/j.ijbiomac.2021.01.028. Epub 2021 Jan 9.
The current study heterologously expressed a cutinase from Fusarium verticillioides by Pichia pastoris and investigated its properties and effects on the hydrolysis of rice straw. The optimal pH and temperature for F. verticillioides cutinase were 8.0 and 50 °C, respectively. F. verticillioides cutinase had poor thermal stability and could be inhibited by some metal ions, inhibitors, and detergents (5 mM), including Ni, Zn, Cu, Ca, Mn, sodium dodecyl sulfate, EDTA, and Tween-20. F. verticillioides cutinase could tolerate 15% methanol and dimethyl sulfoxide but was significantly repressed by 15% ethanol and acetone with 48% and 63% residual activity, respectively. F. verticillioides cutinase could degrade the cuticle of rice straw with palmitic acid and stearic acid as the main products. However, the dissolving sugars released from the rice straw treated with F. verticillioides cutinase were significantly reduced by 29.2 μg/mL compared with the control (107.9 μg/mL). Similarly, the reducing sugars produced from the cellulase hydrolysis of rice straw pretreated with F. verticillioides cutinase were reduced by 63.5 μg/mL relative to the control (253.6 μg/mL). Scanning electron microscopy results showed that numerous tuberculate or warty protrusions were present nearly everywhere on the surface of rice straw treated with F. verticillioides cutinase, and some protrusions even covered and blocked the stomata of the rice straw surface. Current limited data indicate that F. verticillioides cutinase might not be an appropriate choice for improving the utilization of agricultural straws.
本研究通过毕赤酵母异源表达了来自串珠镰刀菌的角质酶，并研究了其性质及其对水稻秸秆水解的影响。毕赤酵母角质酶的最适 pH 和温度分别为 8.0 和 50°C。该酶热稳定性差，一些金属离子、抑制剂和表面活性剂（5 mM）如 Ni、Zn、Cu、Ca、Mn、十二烷基硫酸钠、EDTA 和吐温-20 可以抑制其活性。毕赤酵母角质酶可以耐受 15%甲醇和二甲基亚砜，但 15%乙醇和丙酮分别显著抑制其 48%和 63%的剩余活性。毕赤酵母角质酶可以降解水稻秸秆的角质层，其主要产物为棕榈酸和硬脂酸。然而，与对照（107.9μg/mL）相比，用毕赤酵母角质酶处理的水稻秸秆释放的溶解糖显著减少了 29.2μg/mL。同样，用毕赤酵母角质酶预处理的水稻秸秆经纤维素酶水解产生的还原糖也比对照减少了 63.5μg/mL（253.6μg/mL）。扫描电子显微镜结果表明，经毕赤酵母角质酶处理的水稻秸秆表面几乎到处都有大量的结节状或疣状突起，有些突起甚至覆盖和堵塞了水稻秸秆表面的气孔。目前有限的数据表明，串珠镰刀菌角质酶可能不是提高农业秸秆利用率的合适选择。
