变温操作对黑曲霉A-25产木聚糖酶的影响

Effect of temperature shift operation on xylanase production by Aspergillus niger A-25

试验研究不同温度对黑曲霉生物量和木聚糖酶产量的影响,并通过单位质量菌丝的产酶量和酶谱探究木聚糖酶产量提高的原因。结果显示:黑曲霉A-25在33℃培养时获得最大的生物量,而在29℃时获得最高胞外木聚糖酶分泌量。因此,变温操作采用0~48 h在33℃下培养、之后降为29℃,木聚糖酶活力可达721 U/mL,比29℃恒温发酵提高18%,同时发酵周期缩短8 h。进一步研究发现,0~48 h阶段内变温发酵条件下黑曲霉菌丝体生物量明显增加,并且单位质量菌丝体的产酶能力也有不同程度的提高;木聚糖酶的酶谱检测发现,变温发酵促进木聚糖酶XynⅢ的提前表达,同时提高木聚糖酶XynⅠ和木聚糖酶XynⅡ的表达量。

The experiment studied the effect of different temperatures on the biomass and xylanase production of Aspergillus niger, and explored the reasons for the xylanase production increase through the enzyme activity per unit mass of hyphae and the enzyme spectrum. The results showed that Aspergillus niger A-25 obtained the maximum biomass when cultivated at 33 ℃, and the highest secretion of extracellular xylanase was obtained at 29 ℃. Therefore, the temperature-shift operation was carried out at 33 ℃ for 0~48 h, and then at 29 ℃. The xylanase activity can reach721 U/mL, which was 18% higher than the constant temperature fermentation at 29 °C, and the fermentation time was shortened by 8 h. Further research found that the mycelium biomass of Aspergillus niger increased significantly under temperature-shift fermentation conditions in the 0~48 h stage, and the producing enzyme capacity per unit mass of mycelium was also improved to varying degrees. The xylanase zymogram detection found that variable temperature fermentation promoted the earlier expression of xylanase XynⅢ, and increased the expression of xylanase XynⅠ and XynⅡ at the same time.