Changes in primary metabolism leading to citric acid overflow in Aspergillus niger

Legiša, Matic; Mattey, Michael

doi:10.1007/s10529-006-9235-z

Cited by 49 publications

(46 citation statements)

References 47 publications

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“…Aspergillus niger is able to grow at extreme external pH values (20,24,27). Our results show that conidia of A. niger expressing RaVC were able to germinate, and hyphae grew in media with pH values between 2.5 and 9.5 (Fig.…”

Section: Codon Optimization Was Used To Improve Ravc Expressionmentioning

confidence: 58%

“…Our results show that the cytoplasmic pH is maintained at ϳ7.6 even when the external pH ranges from 2.5 to 9.5. Aspergillus niger is used for citric acid production (20,24,27), and excreted citric acid can acidify its growth environment down to pH 1.5. This organism therefore needs a robust homeostatic mechanism to maintain the cytoplasmic pH at a constant value in order for its cells to survive and function in extreme pH environments.…”

Section: Discussionmentioning

confidence: 99%

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Live-Cell Imaging and Measurement of Intracellular pH in Filamentous Fungi Using a Genetically Encoded Ratiometric Probe

et al. 2009

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A novel, genetically encoded, ratiometric pH probe (RaVC) was constructed to image and measure intracellular pH in living hyphae of Aspergillus niger. RaVC is a chimeric protein based on the pH-sensitive probe pHluorin, which was partially codon optimized for expression in Aspergillus. Intracellular pH imaging and measurement was performed by simultaneous, dual-excitation confocal ratio imaging. The mean cytoplasmic pH measured was 7.4 to 7.7 based on calibrating RaVC in situ within nigericin-treated hyphae. Pronounced, longitudinal cytoplasmic pH gradients were not observed in the apical 20 m of actively growing hyphae at the periphery of 18-h-old colonies. The cytoplasmic pH remained unchanged after prolonged growth in buffered medium with pH values between 2.5 or 9.5. Sudden changes in external pH significantly changed cytoplasmic pH by <1.3 pH units, but it returned to its original value within 20 min following treatment. The weak acid and antifungal food preservative sorbic acid caused prolonged, concentration-dependent intracellular acidification. The inhibition of ATPases with N-ethylmaleimide, dicychlohexylcarbodimide, or sodium azide caused the cytoplasmic pH to decrease by <1 pH unit. Treatment with the protonophore carbonyl cyanide m-chlorophenylhydrazone or cyanide p-(trifluoromethoxy) phenylhydrazone reduced the cytoplasmic pH by <1 pH unit. In older hyphae from 32-h-old cultures, RaVC became sequestered within large vacuoles, which were shown to have pH values between 6.2 and 6.5. Overall, our study demonstrates that RaVC is an excellent probe for visualizing and quantifying intracellular pH in living fungal hyphae.

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Section: Codon Optimization Was Used To Improve Ravc Expressionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Live-Cell Imaging and Measurement of Intracellular pH in Filamentous Fungi Using a Genetically Encoded Ratiometric Probe

et al. 2009

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“…[14][15][16][17][18] Examples include the citric acid production process using A. niger and penicillin production using P. chrysogenum, in which incremental improvements and new insights have been documented over many decades. 15,[19][20][21][22][23][24] The characterization of filamentous fungal hosts for expression of proteins also dominates the literature, and this field has been thoroughly reviewed in recent years. 18,25 …”

Section: Cellular Performance Of Established Fungal Cell Factoriesmentioning

confidence: 99%

Integrated Approaches for Assessment of Cellular Performance in Industrially Relevant Filamentous Fungi

WorkmanMhairi

Andersen

ThykaerJette

2013

Industrial Biotechnology

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The performance of filamentous fungi in submerged cultivation determines their suitability for large-scale industrial biotechnology processes and is the result of complex interplay between the physical and chemical parameters of the process and the cellular biology of the fungi. Filamentous fungi have a natural ability to degrade complex substrates through secretion of a large number of diverse enzymes and to produce a number of metabolites that inhibit or prevent the growth of other species in the surroundings. These features have been exploited by industry, resulting in multi-billion dollar processes for producing enzymes and metabolites of value. However, the wealth of diversity of these species is still not fully represented in large-scale bioprocesses, and thus advancement from discovery to application is one of the challenges for modern biotechnology. Acceleration of the process can be achieved through integrated approaches for assessing cellular performance (quantitative physiology), genetic modification of strains (metabolic engineering), and omics analyses and modeling (systems biology). In this review, we evaluate stateof-the-art of filamentous fungal applications in industrial biotechnology , focusing on physiological aspects of the fungi that provide the basis of their cellular performance. We also discuss the advancement of systems biology approaches and how the establishment of these tools for fungal research has begun to reveal the possibilities for further exploitation of these organisms. Increased future focus on multicellular physiology and relevant assays will lead to fungal cells and processes that are customizable to a greater degree, finally allowing the full potential of these complex organisms and their product diversity to unfold.

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“…Aspergillus is a well known producer of medical drugs, toxins, and widely-used industrial enzymes. In particular, Aspergillus niger (GRAS strain) is recognized as an important producer of enzymes and organic acids (Legiša and Mattey 2007). The complete genome sequences of A. niger CBS513.88 (Pel et al 2007) and ATCC1015 (Andersen et al 2011) have become available, and this has led to the identification of a large number of polyketide (PKS) and non-ribosomal peptide (NRPS) genes.…”

Section: Introductionmentioning

confidence: 99%

Type III polyketide synthase is involved in the biosynthesis of protocatechuic acid in Aspergillus niger

Xiao

Pan

2014

Biotechnol Lett

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Genomic studies have shown that not only plants but also filamentous fungi contain type III polyketide synthases. To study the function of type III polyketide synthase (AnPKSIII) in Aspergillus niger, a deletion strain (delAnPKSIII) and an overexpression strain (oeAnPKSIII) were constructed in A. niger MA169.4, a derivative of the wild-type (WT) A. niger ATCC 9029 that produces large quantities of gluconic acid. Alterations in the metabolites were analyzed by HPLC when the extract of the overexpression strain was compared with extracts of the WT and deletion strains. Protocatechuic acid (PCA; 3,4-dihydroxybenzoic acid, 3.2 mg/l) was isolated and identified as the main product of AnPKSIII when inductively expressed in A. niger MA169.4. The molecular weight of PCA was 154.1 (m/z 153.1 [M-H](-)), was detected by ESI-MS in the negative ionization mode, and (1)H and (13)C NMR data confirmed its structure.

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Changes in primary metabolism leading to citric acid overflow in Aspergillus niger

Cited by 49 publications

References 47 publications

Live-Cell Imaging and Measurement of Intracellular pH in Filamentous Fungi Using a Genetically Encoded Ratiometric Probe

Live-Cell Imaging and Measurement of Intracellular pH in Filamentous Fungi Using a Genetically Encoded Ratiometric Probe

Integrated Approaches for Assessment of Cellular Performance in Industrially Relevant Filamentous Fungi

Type III polyketide synthase is involved in the biosynthesis of protocatechuic acid in Aspergillus niger

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