Liu Peng, Wang Shuai, Li Chao, Zhuang Yingping, Xia Jianye, Noorman Henk
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
DSM Biotechnology Center, Delft, The Netherlands.
Biotechnol Bioeng. 2021 Jun;118(6):2265-2282. doi: 10.1002/bit.27739. Epub 2021 Apr 1.
In industrial large-scale bioreactors, microorganisms encounter heterogeneous substrate concentration conditions, which can impact growth or product formation. Here we carried out an extended (12 h) experiment of repeated glucose pulsing with a 10-min period to simulate fluctuating glucose concentrations with Aspergillus niger producing glucoamylase, and investigated its dynamic response by rapid sampling and quantitative metabolomics. The 10-min period represents worst-case conditions, as in industrial bioreactors the average cycling duration is usually in the order of 1 min. We found that cell growth and the glucoamylase productivity were not significantly affected, despite striking metabolomic dynamics. Periodical dynamic responses were found across all central carbon metabolism pathways, with different time scales, and the frequently reported ATP paradox was confirmed for this A. niger strain under the dynamic conditions. A thermodynamics analysis revealed that several reactions of the central carbon metabolism remained in equilibrium even under periodical dynamic conditions. The dynamic response profiles of the intracellular metabolites did not change during the pulse exposure, showing no significant adaptation of the strain to the more than 60 perturbation cycles applied. The apparent high tolerance of the glucoamylase producing A. niger strain for extreme variations in the glucose availability presents valuable information for the design of robust industrial microbial hosts.
在工业大规模生物反应器中，微生物会遇到非均匀的底物浓度条件，这可能会影响生长或产物形成。在此，我们进行了一项延长（12小时）的实验，以10分钟为周期重复葡萄糖脉冲，模拟黑曲霉产糖化酶时葡萄糖浓度的波动情况，并通过快速取样和定量代谢组学研究其动态响应。10分钟的周期代表了最坏的情况，因为在工业生物反应器中，平均循环持续时间通常在1分钟左右。我们发现，尽管代谢组学动态显著，但细胞生长和糖化酶生产力并未受到显著影响。在所有中心碳代谢途径中都发现了具有不同时间尺度的周期性动态响应，并且在动态条件下证实了该黑曲霉菌株存在经常报道的ATP悖论。热力学分析表明，即使在周期性动态条件下，中心碳代谢的几个反应仍保持平衡。在脉冲暴露期间，细胞内代谢物的动态响应曲线没有变化，表明该菌株对施加的60多个扰动循环没有明显的适应性。产糖化酶的黑曲霉菌株对葡萄糖可用性的极端变化具有明显的高耐受性，这为设计稳健的工业微生物宿主提供了有价值的信息。
