Yang Peizhou, Zhang Haifeng, Cao Lili, Zheng Zhi, Jiang Shaotong
College of Food Science and Engineering, Hefei University of Technology, Hefei, 230009, China.
Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, 230009, China.
3 Biotech. 2016 Dec;6(2):236. doi: 10.1007/s13205-016-0545-0. Epub 2016 Nov 4.
Aspergillus niger is an important microorganism that has been used for decades to produce extracellular enzymes. In this study, a novel Aspergillus niger strain integrated with a eukaryotic expression vector harboring the gpd-Shi promoter of shiitake mushrooms and cellulase gene of Ampullaria gigas Spix was engineered to improve cellulase production for the achievement of highly efficient saccharification of agricultural residues. In one strain, designated ACShi27, which exhibited the highest total cellulase expression, total cellulase, endoglucanase, exoglucanase, and xylanase expression levels were 1.73, 16.23, 17.73, and 150.83 U ml, respectively; these values were 14.5, 22.3, 24.6, and 17.3% higher than those of the wild-type Aspergillus niger M85 using wheat bran as an induction substrate. Production of cellulases and xylanase by solid-state fermentation followed by in situ saccharification of ACShi27 was investigated with alkaline-pretreated rice straw as a substrate. After 2 days of enzyme induction at 30 °C, followed by 48 h of saccharification at 50 °C, the conversion rate of carbon polymers into reducing sugar reached 293.2 mg g, which was 1.23-fold higher than that of the wild-type strain. The expression of sestc in Aspergillus niger can improve the total cellulase and xylanase activity and synergism, thereby enhancing the lignocellulose in situ saccharification.
黑曲霉是一种重要的微生物，几十年来一直被用于生产胞外酶。在本研究中，构建了一种新型黑曲霉菌株，该菌株整合了一个真核表达载体，该载体含有香菇的gpd-Shi启动子和大瓶螺的纤维素酶基因，以提高纤维素酶的产量，从而实现农业残留物的高效糖化。在一种命名为ACShi27的菌株中，其总纤维素酶表达量最高，总纤维素酶、内切葡聚糖酶、外切葡聚糖酶和木聚糖酶的表达水平分别为1.73、16.23、17.73和150.83 U/ml；以麦麸作为诱导底物时，这些值分别比野生型黑曲霉M85高14.5%、22.3%、24.6%和17.3%。以碱预处理稻草为底物，研究了ACShi27固态发酵生产纤维素酶和木聚糖酶并原位糖化的情况。在30℃进行2天的酶诱导，然后在50℃进行48小时的糖化后，碳聚合物转化为还原糖的转化率达到293.2 mg/g，比野生型菌株高1.23倍。黑曲霉中sestc的表达可以提高总纤维素酶和木聚糖酶的活性及协同作用，从而增强木质纤维素的原位糖化。
