Integrated isotope-assisted metabolomics and 13C metabolic flux analysis reveals metabolic flux redistribution for high glucoamylase production by Aspergillus niger
| Autor: | Mingzhi Huang, Jianye Xia, Xiaoyun Liu, Siliang Zhang, Hongzhong Lu, Yingping Zhuang, Henk Noorman, Ju Chu |
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| Rok vydání: | 2015 |
| Předmět: |
Glucose uptake
Citric Acid Cycle Bioengineering Pentose phosphate pathway Applied Microbiology and Biotechnology chemistry.chemical_compound Metabolic flux analysis Metabolomics Biomass Citric acid secretion Amino Acids chemistry.chemical_classification Carbon Isotopes biology Research Aspergillus niger biology.organism_classification Metabolic Flux Analysis 13C metabolic flux analysis Citric acid cycle Kinetics Enzyme chemistry Biochemistry Glucoamylase Glucan 1 4-alpha-Glucosidase Energy Metabolism Citric acid Oxidation-Reduction Cofactor metabolism Biotechnology |
| Zdroj: | Microbial Cell Factories Microbial Cell Factories, 14(1) |
| ISSN: | 1475-2859 |
| DOI: | 10.1186/s12934-015-0329-y |
| Popis: | Background Aspergillus niger is widely used for enzyme production and achievement of high enzyme production depends on the comprehensive understanding of cell’s metabolic regulation mechanisms. Results In this paper, we investigate the metabolic differences and regulation mechanisms between a high glucoamylase-producing strain A. niger DS03043 and its wild-type parent strain A. niger CBS513.88 via an integrated isotope-assisted metabolomics and 13C metabolic flux analysis approach. We found that A. niger DS03043 had higher cell growth, glucose uptake, and glucoamylase production rates but lower oxalic acid and citric acid secretion rates. In response to above phenotype changes, A. niger DS03043 was characterized by an increased carbon flux directed to the oxidative pentose phosphate pathway in contrast to reduced flux through TCA cycle, which were confirmed by consistent changes in pool sizes of metabolites. A higher ratio of ATP over AMP in the high producing strain might contribute to the increase in the PP pathway flux as glucosephosphate isomerase was inhibited at higher ATP concentrations. A. niger CBS513.88, however, was in a higher redox state due to the imbalance of NADH regeneration and consumption, resulting in the secretion of oxalic acid and citric acid, as well as the accumulation of intracellular OAA and PEP, which may in turn result in the decrease in the glucose uptake rate. Conclusions The application of integrated metabolomics and 13C metabolic flux analysis highlights the regulation mechanisms of energy and redox metabolism on flux redistribution in A. niger. Graphical abstractAn integrated isotope-assisted metabolomics and 13C metabolic flux analysis was was firstly systematically performed in A. niger. In response to enzyme production, the metabolic flux in A. niger DS03043 (high-producing) was redistributed, characterized by an increased carbon flux directed to the oxidative pentose phosphate pathway as well as an increased pool size of pentose. The consistency in 13C metabolic flux analysis and metabolites quantification indicated that an imbalance of NADH formation and consumption led to the accumulation and secretion of organic acids in A. niger CBS513.88 (wild-type) Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0329-y) contains supplementary material, which is available to authorized users. |
| Databáze: | OpenAIRE |
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