Manganese(II) ions suppress the transcription of the citrate exporter encoding gene cexA in Aspergillus niger

is an important filamentous fungus used for the industrial production of citric acid. One of the most important factors that affect citric acid production is the concentration of manganese(II) ions present in the culture broth. Under manganese(II)-limiting conditions, the fungus develops a pellet-li...

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Bibliographic Details
Published in:Frontiers in bioengineering and biotechnology 2023, Vol.11, p.1292337-1292337
Main Authors: Reinfurt, Aline, Fritsche, Susanne, Bíró, Vivien, Márton, Alexandra, Ellena, Valeria, Fekete, Erzsébet, Sándor, Erzsébet, Karaffa, Levente, Steiger, Matthias G
Format: Article
Language:English
Subjects:
Aspergillus niger
cexA regulation
citric acid overflow
citric acid transporter
manganese effect
metal ions
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Summary:is an important filamentous fungus used for the industrial production of citric acid. One of the most important factors that affect citric acid production is the concentration of manganese(II) ions present in the culture broth. Under manganese(II)-limiting conditions, the fungus develops a pellet-like morphology that is crucial for high citric acid accumulation. The impact of manganese(II) ions on the transcription of the major citrate exporter encoding gene was studied under manganese(II)-deficient and -sufficient conditions. Furthermore, citric acid production was analyzed in overexpression mutant strains of in the presence and absence of manganese(II) ions, and the influence of CexA on fungal morphology was investigated by microscopy. Transcriptional upregulation of in the absence of manganese(II) ions was observed and, by decoupling expression from the native promoter system, it was possible to secrete more citric acid even in the presence of manganese. This effect was shown for both an inducible and a constitutive overexpression of . Furthermore, it was found that the presence of CexA influences fungal morphology and promotes a more branched phenotype. According to this study, manganese(II) ions suppress transcription of the citrate exporter in , causing citric acid secretion to decrease.
ISSN:2296-4185
2296-4185
DOI:10.3389/fbioe.2023.1292337