解糖热解纤维素菌F32降解未预处理秸秆及产纤维素酶特性分析

Degradation of unpretreated wheat straw by Caldicellulosiruptor saccharolyticus F32 and its enzyme characteristics

摘要:

【目的】明确极端嗜热厌氧木质纤维素降解菌解糖热解纤维素菌F32代谢特征，并分析其产酶特性。【方法】使用细胞计数法绘制菌株的生长曲线，使用离子色谱及气相色谱进行产物和残糖量分析，以DNS法及对硝基苯酚法检测菌株胞外蛋白的酶活性。【结果】解糖热解纤维素菌F32在以葡萄糖、微晶纤维素和未经预处理小麦秸秆为碳源时生长状况优于解糖热解纤维素菌DSM 8903。在以葡萄糖为碳源进行培养时，与菌株DSM 8903相比，菌株F32具有产乳酸较多，而产氢气较少的特点。在以微晶纤维素和未经预处理小麦秸秆为碳源进行培养时，与菌株DSM 8903相比，菌株F32胞外蛋白具有较高的内切纤维素酶活性和木聚糖酶活性。【结论】解糖热解纤维素菌F32表现出较强的木质纤维素降解能力，其与DSM 8903的产物组成及胞外蛋白的酶活性具有明显差异。

Abstract:

[Objective] This study is aimed to characterize fermentation and enzyme characteristics of an extremely thermophilic anaerobic lignocellulolytic bacterium Caldicellulosiruptor saccharolyticus F32. [Methods] Cell growth was monitored by cell counting. Acetate, lactate and residual reducing sugars were measured by using an ion chromatography system. H2 was detected by gas chromatography. DNS method and p-nitrophenyl method were used to measure the enzyme activities of the secreted proteins of C. saccharolyticus F32 and DSM 8903. [Results] In contrast to C. saccharolyticus DSM 8903, strain F32 grew better on cellulose (Avicel PH-101), even on unpretreated wheat straw. Compared to C. saccharolyticus DSM 8903, strain F32 produced more lactate as the end product, thereby decreasing the hydrogen yield when glucose was used as carbon source. The secretome of strain F32 showed higher endoglucanase and xylanase activities. [Conclusion] In comparison with C. saccharolyticus DSM 8903, C. saccharolyticus F32 could degrade lignocellulosic biomass more efficiently. There were significant difference in the products, cellulase and hemicellulase systems between C. saccharolyticus F32 and C. saccharolyticus DSM 8903.