Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters

C4-dicarboxylic acids are essential organic compounds characterized by a four-carbon structure and two carboxyl groups. Their export from cells is mediated by specialized transporter proteins known as C4-dicarboxylic acid transporters (DCTs). The objective of this study was to investigate the specif...

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Main Authors: Yiyang Tan, Shutong Liu, Sheng Wu, Xiaolu Wang, Depei Wang, Xianli Xue
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Fermentation
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Online Access:https://www.mdpi.com/2311-5637/11/3/156
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author Yiyang Tan
Shutong Liu
Sheng Wu
Xiaolu Wang
Depei Wang
Xianli Xue
author_facet Yiyang Tan
Shutong Liu
Sheng Wu
Xiaolu Wang
Depei Wang
Xianli Xue
author_sort Yiyang Tan
collection DOAJ
description C4-dicarboxylic acids are essential organic compounds characterized by a four-carbon structure and two carboxyl groups. Their export from cells is mediated by specialized transporter proteins known as C4-dicarboxylic acid transporters (DCTs). The objective of this study was to investigate the specificity of six DCTs (DCT1-5 and C4t318) from <i>Aspergillus niger</i> or <i>Aspergillus oryzae</i>, focusing on their role in different production strategies for C4-dicarboxylic acids. The results indicate that compared to the WT strain, overexpressing <i>dct</i>2 or <i>dct</i>3 in <i>A. niger</i> CGMCC NO. 40550 specifically enhances the production of succinic acid, increasing its yield from 5.69 g/L to 6.28 g/L, and L-malic acid, increasing its yield from 11.02 g/L to 12.11 g/L. Additionally, <i>dct</i>5 appears to be involved in the transport of both succinic acid (6.19 g/L) and L-malic acid (16.33 g/L). The total acid yields of T-D3-7, which lacks the oxaloacetate hydrolase gene, were improved to 27.75 g/L, compared to 25.19 g/L for T-D3-26, due to blocking the branch of oxaloacetate metabolism. Furthermore, the heterologous expression of <i>A. oryzae</i> C4T318 in <i>A. niger</i> increased the production of L-malic acid by approximately 22.5%. Furthermore, the best results were observed when the strains T-D3-7 and T-D5-16 were scaled up in a 30 L bioreactor for 84 h. The succinic acid and L-malic acid yields of T-D3-7 and T-D5-16 reached 14.51 g/L and 70.79 g/L or 41.59 g/L and 81.08 g/L, respectively. Moreover, the purity of L-malic acid produced by T-D3-7 reached 71%. This work further clarifies the specificity of C4-dicarboxylic acid transporters and provides valuable insights for optimizing organic acid production.
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series Fermentation
spelling doaj-art-2eceea72caa7427384a3485d055d47972025-08-20T03:43:33ZengMDPI AGFermentation2311-56372025-03-0111315610.3390/fermentation11030156Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid TransportersYiyang Tan0Shutong Liu1Sheng Wu2Xiaolu Wang3Depei Wang4Xianli Xue5Key Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, ChinaKey Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, ChinaKey Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, ChinaKey Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, ChinaKey Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, ChinaC4-dicarboxylic acids are essential organic compounds characterized by a four-carbon structure and two carboxyl groups. Their export from cells is mediated by specialized transporter proteins known as C4-dicarboxylic acid transporters (DCTs). The objective of this study was to investigate the specificity of six DCTs (DCT1-5 and C4t318) from <i>Aspergillus niger</i> or <i>Aspergillus oryzae</i>, focusing on their role in different production strategies for C4-dicarboxylic acids. The results indicate that compared to the WT strain, overexpressing <i>dct</i>2 or <i>dct</i>3 in <i>A. niger</i> CGMCC NO. 40550 specifically enhances the production of succinic acid, increasing its yield from 5.69 g/L to 6.28 g/L, and L-malic acid, increasing its yield from 11.02 g/L to 12.11 g/L. Additionally, <i>dct</i>5 appears to be involved in the transport of both succinic acid (6.19 g/L) and L-malic acid (16.33 g/L). The total acid yields of T-D3-7, which lacks the oxaloacetate hydrolase gene, were improved to 27.75 g/L, compared to 25.19 g/L for T-D3-26, due to blocking the branch of oxaloacetate metabolism. Furthermore, the heterologous expression of <i>A. oryzae</i> C4T318 in <i>A. niger</i> increased the production of L-malic acid by approximately 22.5%. Furthermore, the best results were observed when the strains T-D3-7 and T-D5-16 were scaled up in a 30 L bioreactor for 84 h. The succinic acid and L-malic acid yields of T-D3-7 and T-D5-16 reached 14.51 g/L and 70.79 g/L or 41.59 g/L and 81.08 g/L, respectively. Moreover, the purity of L-malic acid produced by T-D3-7 reached 71%. This work further clarifies the specificity of C4-dicarboxylic acid transporters and provides valuable insights for optimizing organic acid production.https://www.mdpi.com/2311-5637/11/3/156<i>Aspergillus niger</i>C4-dicarboxylic acid transportersorganic acidoverexpressionbioreactor fermentationreal-time fluorescence quantitative PCR
spellingShingle Yiyang Tan
Shutong Liu
Sheng Wu
Xiaolu Wang
Depei Wang
Xianli Xue
Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
Fermentation
<i>Aspergillus niger</i>
C4-dicarboxylic acid transporters
organic acid
overexpression
bioreactor fermentation
real-time fluorescence quantitative PCR
title Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
title_full Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
title_fullStr Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
title_full_unstemmed Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
title_short Improving Organic Acid Secretion of <i>Aspergillus niger</i> by Overexpression C4-Dicarboxylic Acid Transporters
title_sort improving organic acid secretion of i aspergillus niger i by overexpression c4 dicarboxylic acid transporters
topic <i>Aspergillus niger</i>
C4-dicarboxylic acid transporters
organic acid
overexpression
bioreactor fermentation
real-time fluorescence quantitative PCR
url https://www.mdpi.com/2311-5637/11/3/156
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