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[Objective] To investigate the enzymatic properties and straw-degrading effect of a recombinant xylanase rRuXyn024. [Methods] We cloned RuXyn024 from the rumen of beef cattle and used bioinformatics tools for detailed sequence analysis. The expression vector pET-RuXyn024 was constructed and transformed into Escherichia coli BL21(DE3) for heterologous expression of RuXyn024. Furthermore, the enzymatic properties and straw-degrading effect of rRuXyn024 were examined. [Results] RuXyn024 was composed of 358 amino acid residues and had a molecular weight of approximately 40 kDa, belonging to the GH 10 family. The optimal pH and temperature of rRuXyn024 were pH 7.0 and 40 ℃, respectively. The relative activity of RuXyn024 at pH 6.0−9.0 and 30−70 ℃ remained above 60% and 70%, respectively. With xylan from wheat straw as the substrate, rRuXyn024 showcased the Km and Vmax of 18.8 g/L and 82.6 µg/min, respectively. The activity of rRuXyn024 was inhibited by Mg2+, Zn2+, Cu2+, Ni2+, EDTA, and SDS at 1 mmol/L and 5 mmol/L, as well as 5 mmol/L Ca2+ and β-mercaptoethanol. Cu2+ and β-mercaptoethanol at 5 mmol/L nearly inactivated the enzyme. Mn2+ at 1 mmol/L and 5 mmol/L increased the activity of rRuXyn024 by 46.9% and 35.8%, respectively. The degradation of xylan from wheat straw by rRuXyn024 produced oligosaccharides, including xylotriose and xylobiose. rRuXyn024 could degrade maize straw, rice straw, soybean straw, and rapeseed straw, with the strongest degrading effect on maize straw. [Conclusion] rRuXyn024 exhibits tolerance to broad scopes of pH and temperature and significant potential for improving the utilization of straw by ruminants.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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