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Wu X, Zhang T, Zhang K, Zhang R, Shi M, Gu C, Shi T, Lu L, Xue F, Xu Q, Zhang C. The forced activation of asexual conidiation in Aspergillus niger simplifies bioproduction. Synth Syst Biotechnol 2024; 9:277-284. [PMID: 38496318 PMCID: PMC10942867 DOI: 10.1016/j.synbio.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/22/2024] [Accepted: 02/28/2024] [Indexed: 03/19/2024] Open
Abstract
Aspergillus niger is an efficient cell factory for organic acids production, particularly l-malic acid, through genetic manipulation. However, the traditional method of collecting A. niger spores for inoculation is labor-intensive and resource-consuming. In our study, we used the CRISPR-Cas9 system to replace the promoter of brlA, a key gene in Aspergillus conidiation, with a xylose-inducible promoter xylP in l-malic acid-producing A. niger strain RG0095, generating strain brlAxylP. When induced with xylose in submerged liquid culture, brlAxylP exhibited significant upregulation of conidiation-related genes. This induction allowed us to easily collect an abundance of brlAxylP spores (>7.1 × 106/mL) in liquid xylose medium. Significantly, the submerged conidiation approach preserves the substantial potential of A. niger as a foundational cellular platform for the biosynthesis of organic acids, including but not limited to l-malic acid. In summary, our study offers a simplified submerged conidiation strategy to streamline the preparation stage and reduce labor and material costs for industrial organic acid production using Aspergillus species.
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Affiliation(s)
- Xingyu Wu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Tingting Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Ke Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Rui Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Man Shi
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Chenlei Gu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Tianqiong Shi
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Ling Lu
- College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China
| | - Feng Xue
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Qing Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Chi Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
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Zhang C, Shi M, Xu Y, Yang D, Lu L, Xue F, Xu Q. Conditional expression of FumA in Aspergillus niger enhances synthesis of L-malic acid. Appl Environ Microbiol 2024; 90:e0000824. [PMID: 38506527 PMCID: PMC11022578 DOI: 10.1128/aem.00008-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 02/06/2024] [Indexed: 03/21/2024] Open
Abstract
Currently, the L-malic acid titer achieved through Aspergillus niger fermentation reaches 201 g/L, meeting industrial demands satisfactorily. However, the co-presence of structurally similar fumaric acid and succinic acid in fermentation products suggests a theoretical potential for further improvement in L-malic acid production. In the tricarboxylic acid cycle, fumarate reductase mediates the conversion of succinic acid to fumaric acid. Subsequently, fumarase catalyzes the conversion of fumaric acid to L-malic acid. Notably, both enzymatic reactions are reversible. Our investigation revealed that A. niger contains only one mitochondria-located fumarase FumA. Employing CRISPR-Cas9 technology, we performed a replacement of the fumA promoter with a doxycycline-induced promoter Tet. Under non-inducing condition, the conditional strain exhibited increased levels of fumaric acid and succinic acid. It strongly suggests that FumA mainly promotes the flow of fumaric acid to L-malic acid. Furthermore, a promoter PmfsA that is exclusively activated in a fermentation medium by calcium carbonate was identified through RNA-sequencing screening. Utilizing PmfsA to regulate fumA expression led to a 9.0% increase in L-malic acid titer, an 8.75% increase in yield (glucose to L-malic acid), and an 8.86% enhancement in productivity. This research serves as a significant step toward expediting the industrialization of L-malic acid synthesis via biological fermentation. Additionally, it offers valuable insights for the biosynthesis of other organic acids.IMPORTANCEThis study focuses on enhancing L-malic acid synthesis by modifying the tricarboxylic acid cycle within the mitochondria of Aspergillus niger. We emphasize the significant role of fumarase in converting fumaric acid into L-malic acid, enhancing our understanding of metabolic pathways in A. niger. The precise regulation of fumA is highlighted as a key factor in enhancing L-malic acid production. Furthermore, this research introduces a stringent conditional promoter (PmfsA), exclusively activated by CaCO3. The utilization of PmfsA for fumA expression resulted in heightened L-malic acid titers. The progress in metabolic engineering and bioprocess optimization holds promise for expediting industrial L-malic acid synthesis via biological fermentation. Moreover, it carries implications for the biosynthesis of various other organic acids.
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Affiliation(s)
- Chi Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Man Shi
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Yingyan Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Dongdong Yang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Ling Lu
- College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Feng Xue
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Qing Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
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Gu S, Zhu F, Zhang L, Wen J. Mid-Long Chain Dicarboxylic Acid Production via Systems Metabolic Engineering: Progress and Prospects. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:5555-5573. [PMID: 38442481 DOI: 10.1021/acs.jafc.4c00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Mid-to-long-chain dicarboxylic acids (DCAi, i ≥ 6) are organic compounds in which two carboxylic acid functional groups are present at the terminal position of the carbon chain. These acids find important applications as structural components and intermediates across various industrial sectors, including organic compound synthesis, food production, pharmaceutical development, and agricultural manufacturing. However, conventional petroleum-based DCA production methods cause environmental pollution, making sustainable development challenging. Hence, the demand for eco-friendly processes and renewable raw materials for DCA production is rising. Owing to advances in systems metabolic engineering, new tools from systems biology, synthetic biology, and evolutionary engineering can now be used for the sustainable production of energy-dense biofuels. Here, we explore systems metabolic engineering strategies for DCA synthesis in various chassis via the conversion of different raw materials into mid-to-long-chain DCAs. Subsequently, we discuss the future challenges in this field and propose synthetic biology approaches for the efficient production and successful commercialization of these acids.
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Affiliation(s)
- Shanna Gu
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals Co., Ltd, Dalian 116045, China
| | - Fuzhou Zhu
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
| | - Lin Zhang
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals Co., Ltd, Dalian 116045, China
| | - Jianping Wen
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
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Yang D, Xu Y, Mo L, Shi M, Wu N, Lu L, Xue F, Xu Q, Zhang C. Enhancing l-Malic Acid Production in Aspergillus niger via Natural Activation of sthA Gene Expression. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:4869-4879. [PMID: 38407053 DOI: 10.1021/acs.jafc.3c09321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The efficient production of l-malic acid using Aspergillus niger requires overcoming challenges in synthesis efficiency and excessive byproduct buildup. This study addresses these hurdles, improving the activity of NADH-dependent malate dehydrogenase (Mdh) in the early stages of the fermentation process. By employing a constitutive promoter to express the Escherichia coli sthA responsible for the transfer of reducing equivalents between NAD(H) and NADP(H) in A. niger, the l-malic acid production was significantly elevated. However, this resulted in conidiation defects of A. niger, limiting industrial viability. To mitigate this, we discovered and utilized the PmfsA promoter, enabling the specific expression of sthA during the fermentation stage. This conditional expression strain showed similar phenotypes to its parent strain while exhibiting exceptional performance in a 5 L fermenter. Notably, it achieved a 65.5% increase in productivity, reduced fermentation cycle by 1.5 days, and lowered succinic acid by 76.2%. This work marks a promising advancement in industrial l-malic acid synthesis via biological fermentation, showcasing the potential of synthetic biology in A. niger for broader applications.
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Affiliation(s)
- Dongdong Yang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Yingyan Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Li Mo
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Man Shi
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Na Wu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Ling Lu
- College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Feng Xue
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Qing Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
| | - Chi Zhang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China
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Xu B, Zhang W, Zhao E, Hong J, Chen X, Wei Z, Li X. Unveiling malic acid biorefinery: Comprehensive insights into feedstocks, microbial strains, and metabolic pathways. BIORESOURCE TECHNOLOGY 2024; 394:130265. [PMID: 38160850 DOI: 10.1016/j.biortech.2023.130265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/24/2023] [Accepted: 12/25/2023] [Indexed: 01/03/2024]
Abstract
The over-reliance on fossil fuels and resultant environmental issues necessitate sustainable alternatives. Microbial fermentation of biomass for malic acid production offers a viable, eco-friendly solution, enhancing resource efficiency and minimizing ecological damage. This review covers three core aspects of malic acid biorefining: feedstocks, microbial strains, and metabolic pathways. It emphasizes the significance of utilizing biomass sugars, including the co-fermentation of different sugar types to improve feedstock efficiency. The review discusses microbial strains for malic acid fermentation, addressing challenges related to by-products from biomass breakdown and strategies for overcoming them. It delves into the crucial pathways and enzymes for malic acid production, outlining methods to optimize its metabolism, focusing on enzyme regulation, energy balance, and yield enhancement. These insights contribute to advancing the field of consolidated bioprocessing in malic acid biorefining.
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Affiliation(s)
- Boyang Xu
- Anhui Fermented Food Engineering Research Center, School of Food and Biological Engineering, Hefei University of Technology, Hefei City 230009, Anhui Province, PR China
| | - Wangwei Zhang
- Anhui Fermented Food Engineering Research Center, School of Food and Biological Engineering, Hefei University of Technology, Hefei City 230009, Anhui Province, PR China
| | - Eryong Zhao
- Anhui Fermented Food Engineering Research Center, School of Food and Biological Engineering, Hefei University of Technology, Hefei City 230009, Anhui Province, PR China
| | - Jiong Hong
- School of Life Sciences, University of Science and Technology of China, Hefei City 230026, Anhui Province, PR China
| | - Xiangsong Chen
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei City 230031, Anhui Province, PR China
| | - Zhaojun Wei
- School of Biological Sciences and Engineering, North Minzu University, Yinchuan City 750030, Ningxia Hui Autonomous Region, PR China.
| | - Xingjiang Li
- Anhui Fermented Food Engineering Research Center, School of Food and Biological Engineering, Hefei University of Technology, Hefei City 230009, Anhui Province, PR China.
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