Expansions and reductions in fungal primary metabolism studied across 100 fungal species

Julian Brandla, Jane Nyboa, Tammi C. Vestha and Mikael Rørdam Andersena

Author address: 

aDepartment of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby, DK


The primary metabolism of fungi is the power house that drives nearly all cellular functions. Primary
metabolism is involved in converting the surroundings of the fungus to a food source as well as delivering
metabolite precursors for everything from cellular growth and maintenance over biological responses to
external stimuli to producing secreted secondary metabolites and protein effectors. Furthermore, it is
known that fungal metabolism is highly versatile. Saphrophytic fungi can grow on a very wide range of
carbon and nitrogen sources and utilize this for production of even more diverse range of secondary
metabolites and secreted proteins.
Within this project, we have been interested in two main things: 1) What is the "roadmap" of fungal
metabolism within a single species? What is the total sum of genes involved in primary metabolism? For
studying this, we have been focusing on the industrial workhorse and model fungus Aspergillus niger. 2)
What is the diversity of metabolism across fungi? Which gene functions are expanded, reduced, added
and lost across species? For this we have used the metabolic "roadmap" of Aspergillus niger, and used it
to query the genomes of approximately 100 different species, primarily of the genus Aspergillus.
For the initial roadmap of fungal metabolism, we have reconstructed the metabolism of A. niger ATCC
1015 at genome-scale. The metabolic reconstruction covers 1801 metabolic conversions, 997 genes, and
1411 metabolites across six compartments. Phenotype arrays have been applied to evaluate the ability to
germinate on 180 carbon sources and 92 nitrogen sources. Examining the metabolism shows a high
degree of isoenzymes across both central and outer metabolism.
Employing this metabolic network to our database of fungal genomes allows us to examine the diversity
of metabolic strategies through the identification of orthologs across species and map this to the species.
Our analysis shows that some specialized fungi have a more reduced genome and survives with 1-2
isoenzymes for most of central metabolism, while others apply a diversification strategy and often have 2-
5 isoenzymes, even for the highly conserved functions in central metabolism.


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Full conference title: 

The Fourteenth International Aspergillus Meeting, Asilomar Conference Center, Pacific Grove, CA, USA
    • Asperfest 14 (2017)