Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger
Abstract Background Bio-based production of organic acids promises to be an attractive alternative for the chemicals industry to substitute petrochemicals as building-block chemicals. In recent years, itaconic acid (IA, methylenesuccinic acid) has been established as a sustainable building-block che...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2019-09-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-019-1577-6 |
| _version_ | 1818229103980969984 |
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| author | Abeer H. Hossain Roy van Gerven Karin M. Overkamp Peter S. Lübeck Hatice Taşpınar Mustafa Türker Peter J. Punt |
| author_facet | Abeer H. Hossain Roy van Gerven Karin M. Overkamp Peter S. Lübeck Hatice Taşpınar Mustafa Türker Peter J. Punt |
| author_sort | Abeer H. Hossain |
| collection | DOAJ |
| description | Abstract Background Bio-based production of organic acids promises to be an attractive alternative for the chemicals industry to substitute petrochemicals as building-block chemicals. In recent years, itaconic acid (IA, methylenesuccinic acid) has been established as a sustainable building-block chemical for the manufacture of various products such as synthetic resins, coatings, and biofuels. The natural IA producer Aspergillus terreus is currently used for industrial IA production; however, the filamentous fungus Aspergillus niger has been suggested to be a more suitable host for this purpose. In our previous report, we communicated the overexpression of a putative cytosolic citrate synthase citB in an A. niger strain carrying the full IA biosynthesis gene cluster from A. terreus, which resulted in the highest final titer reported for A. niger (26.2 g/L IA). In this research, we have attempted to improve this pathway by increasing the cytosolic acetyl-CoA pool. Additionally, we have also performed fermentation optimization by varying the nitrogen source and concentration. Results To increase the cytosolic acetyl-CoA pool, we have overexpressed genes acl1 and acl2 that together encode for ATP-citrate lyase (ACL). Metabolic engineering of ACL resulted in improved IA production through an apparent increase in glycolytic flux. Strains that overexpress acl12 show an increased yield, titer and productivity in comparison with parental strain CitB#99. Furthermore, IA fermentation conditions were improved by nitrogen supplementation, which resulted in alkalization of the medium and thereby reducing IA-induced weak-acid stress. In turn, the alkalizing effect of nitrogen supplementation enabled an elongated idiophase and allowed final titers up to 42.7 g/L to be reached at a productivity of 0.18 g/L/h and yield of 0.26 g/g in 10-L bioreactors. Conclusion Ultimately, this study shows that metabolic engineering of ACL in our rewired IA biosynthesis pathway leads to improved IA production in A. niger due to an increase in glycolytic flux. Furthermore, IA fermentation conditions were improved by nitrogen supplementation that alleviates IA induced weak-acid stress and extends the idiophase. |
| first_indexed | 2024-12-12T10:13:17Z |
| format | Article |
| id | doaj.art-2de940f14bc1413b804cf51c9a97dd7b |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-12T10:13:17Z |
| publishDate | 2019-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-2de940f14bc1413b804cf51c9a97dd7b2022-12-22T00:27:43ZengBMCBiotechnology for Biofuels1754-68342019-09-0112111410.1186/s13068-019-1577-6Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus nigerAbeer H. Hossain0Roy van Gerven1Karin M. Overkamp2Peter S. Lübeck3Hatice Taşpınar4Mustafa Türker5Peter J. Punt6Dutch DNA Biotech B.V.Dutch DNA Biotech B.V.Dutch DNA Biotech B.V.Section for Sustainable Biotechnology, Department of Chemistry and Bioscience, Aalborg UniversityPakmayaPakmayaDutch DNA Biotech B.V.Abstract Background Bio-based production of organic acids promises to be an attractive alternative for the chemicals industry to substitute petrochemicals as building-block chemicals. In recent years, itaconic acid (IA, methylenesuccinic acid) has been established as a sustainable building-block chemical for the manufacture of various products such as synthetic resins, coatings, and biofuels. The natural IA producer Aspergillus terreus is currently used for industrial IA production; however, the filamentous fungus Aspergillus niger has been suggested to be a more suitable host for this purpose. In our previous report, we communicated the overexpression of a putative cytosolic citrate synthase citB in an A. niger strain carrying the full IA biosynthesis gene cluster from A. terreus, which resulted in the highest final titer reported for A. niger (26.2 g/L IA). In this research, we have attempted to improve this pathway by increasing the cytosolic acetyl-CoA pool. Additionally, we have also performed fermentation optimization by varying the nitrogen source and concentration. Results To increase the cytosolic acetyl-CoA pool, we have overexpressed genes acl1 and acl2 that together encode for ATP-citrate lyase (ACL). Metabolic engineering of ACL resulted in improved IA production through an apparent increase in glycolytic flux. Strains that overexpress acl12 show an increased yield, titer and productivity in comparison with parental strain CitB#99. Furthermore, IA fermentation conditions were improved by nitrogen supplementation, which resulted in alkalization of the medium and thereby reducing IA-induced weak-acid stress. In turn, the alkalizing effect of nitrogen supplementation enabled an elongated idiophase and allowed final titers up to 42.7 g/L to be reached at a productivity of 0.18 g/L/h and yield of 0.26 g/g in 10-L bioreactors. Conclusion Ultimately, this study shows that metabolic engineering of ACL in our rewired IA biosynthesis pathway leads to improved IA production in A. niger due to an increase in glycolytic flux. Furthermore, IA fermentation conditions were improved by nitrogen supplementation that alleviates IA induced weak-acid stress and extends the idiophase.http://link.springer.com/article/10.1186/s13068-019-1577-6Itaconic acidAspergillus nigerTranscriptome analysisMetabolic engineeringATP-citrate lyaseFermentation optimization |
| spellingShingle | Abeer H. Hossain Roy van Gerven Karin M. Overkamp Peter S. Lübeck Hatice Taşpınar Mustafa Türker Peter J. Punt Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger Biotechnology for Biofuels Itaconic acid Aspergillus niger Transcriptome analysis Metabolic engineering ATP-citrate lyase Fermentation optimization |
| title | Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger |
| title_full | Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger |
| title_fullStr | Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger |
| title_full_unstemmed | Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger |
| title_short | Metabolic engineering with ATP-citrate lyase and nitrogen source supplementation improves itaconic acid production in Aspergillus niger |
| title_sort | metabolic engineering with atp citrate lyase and nitrogen source supplementation improves itaconic acid production in aspergillus niger |
| topic | Itaconic acid Aspergillus niger Transcriptome analysis Metabolic engineering ATP-citrate lyase Fermentation optimization |
| url | http://link.springer.com/article/10.1186/s13068-019-1577-6 |
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