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Metabolic activity in dormant conidia ofAspergillus nigerand developmental changes during conidial outgrowth

Novodvorska, Michaela; Stratford, Malcolm; Blythe, Martin J.; Wilson, Raymond; Beniston, Richard G.; Archer, David B.

Authors

Michaela Novodvorska

Malcolm Stratford

Martin J. Blythe

Raymond Wilson

Richard G. Beniston

David B. Archer



Abstract

The early stages of development of Aspergillus niger conidia during outgrowth were explored by combining genome-wide gene expression analysis (RNAseq), proteomics, Warburg manometry and uptake studies. Resting conidia suspended in water were demonstrated for the first time to be metabolically active as low levels of oxygen uptake and the generation of carbon dioxide were detected, suggesting that low-level respiratory metabolism occurs in conidia for maintenance. Upon triggering of spore germination, generation of CO2 increased dramatically. For a short period, which coincided with mobilisation of the intracellular polyol, trehalose, there was no increase in uptake of O2 indicating that trehalose was metabolised by fermentation. Data from genome-wide mRNA profiling showed the presence of transcripts associated with fermentative and respiratory metabolism in resting conidia. Following triggering of conidial outgrowth, there was a clear switch to respiration after 25 min, confirmed by cyanide inhibition. No effect of SHAM, salicylhydroxamic acid, on respiration suggests electron flow via cytochrome c oxidase. Glucose entry into spores was not detectable before 1 h after triggering germination. The impact of sorbic acid on germination was examined and we showed that it inhibits glucose uptake. O2 uptake was also inhibited, delaying the onset of respiration and extending the period of fermentation. In conclusion, we show that conidia suspended in water are not completely dormant and that conidial outgrowth involves fermentative metabolism that precedes respiration.

Citation

Novodvorska, M., Stratford, M., Blythe, M. J., Wilson, R., Beniston, R. G., & Archer, D. B. (in press). Metabolic activity in dormant conidia ofAspergillus nigerand developmental changes during conidial outgrowth. Fungal Genetics and Biology, https://doi.org/10.1016/j.fgb.2016.07.002

Journal Article Type Article
Acceptance Date Jul 1, 2016
Online Publication Date Jul 1, 2016
Deposit Date Jul 18, 2016
Publicly Available Date Jul 18, 2016
Journal Fungal Genetics and Biology
Print ISSN 1087-1845
Electronic ISSN 1087-1845
Publisher Elsevier
Peer Reviewed Peer Reviewed
DOI https://doi.org/10.1016/j.fgb.2016.07.002
Keywords Aspergillus niger; Conidial development; Manometry; RNAseq; Proteome; Sorbic acid
Public URL http://eprints.nottingham.ac.uk/id/eprint/34682
Publisher URL http://dx.doi.org/10.1016/j.fgb.2016.07.002
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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