重组黑曲霉内切菊粉酶高密度细胞生产的生物工艺优化。
Bioprocess Optimisation for High Cell Density Endoinulinase Production from Recombinant Aspergillus niger.
机构信息
Department of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
出版信息
Appl Biochem Biotechnol. 2021 Oct;193(10):3271-3286. doi: 10.1007/s12010-021-03592-y. Epub 2021 Jun 11.
Endoinulinase gene was expressed in recombinant Aspergillus niger for selective and high-level expression using an exponential fed-batch fermentation. The effects of the growth rate (μ), glucose feed concentration, nitrogen concentration and fungal morphology on enzyme production were evaluated. A recombinant endoinulinase with a molecular weight of 66 kDa was secreted. Endoinulinase production was growth associated at μ> 0.04 h, which is characteristic of the constitutive gpd promoter used for the enzyme production. The highest volumetric activity (670 U/ml) was achieved at a growth rate of 93% of μ (0.07 h), while enzyme activity (506 U/ml) and biomass substrate yield (0.043 g/g) significantly decreased at low μ (0.04 h). Increasing the feed concentration resulted in high biomass concentrations and viscosity, which necessitated high agitation to enhance the mixing efficiency and oxygen. However, the high agitation and low DO levels (ca. 8% of saturation) led to pellet disruption and growth in dispersed morphology. Enzyme production profiles, product (Y) and biomass (Y) yield coefficients were not affected by feed concentration and morphological change. The gradual increase in the concentration of nitrogen sources showed that, a nitrogen limited culture was not suitable for endoinulinase production in recombinant A. niger. Moreover, the increase in enzyme volumetric activity was still directly related to an increase in biomass concentration. An increase in nitrogen concentration, from 3.8 to 12 g/L, resulted in volumetric activity increase from 393 to 670 U/ml, but the Y (10053 U/g) and Y (0.049 g/g) did not significantly change. The data demonstrated the potential of recombinant A. niger and high cell density fermentation for the development of large-scale endoinulinase production system.
内切菊粉酶基因在重组黑曲霉中表达,采用指数分批发酵进行选择性和高水平表达。评估了生长速率(μ)、葡萄糖补料浓度、氮浓度和真菌形态对酶生产的影响。分泌了一种分子量为 66 kDa 的重组内切菊粉酶。在μ>0.04 h 时,内切菊粉酶的生产与生长相关,这是用于酶生产的组成型 gpd 启动子的特征。在μ(0.07 h)的 93%时,实现了最高的比体积活性(670 U/ml),而酶活性(506 U/ml)和生物质底物产率(0.043 g/g)在低μ(0.04 h)时显著降低。增加补料浓度会导致高生物质浓度和高粘度,这需要高搅拌来提高混合效率和氧气。然而,高搅拌和低 DO 水平(约 8%饱和度)会导致颗粒破裂和分散形态的生长。酶生产曲线、产物(Y)和生物质(Y)产率系数不受补料浓度和形态变化的影响。氮源浓度的逐渐增加表明,氮限制培养不适合重组黑曲霉内切菊粉酶的生产。此外,酶比体积活性的增加仍与生物质浓度的增加直接相关。氮浓度从 3.8 增加到 12 g/L,导致比体积活性从 393 增加到 670 U/ml,但 Y(10053 U/g)和 Y(0.049 g/g)没有显著变化。这些数据表明了重组黑曲霉和高密度发酵在开发大规模内切菊粉酶生产系统方面的潜力。