Darkness, oxygen deprivation, and vitamin make fungus “crave sex”
Unlike we thought for 100 years: moulds are able to reproduce sexually
PNAS: researchers grow penicillin-producing fungi with new properties
Only penicillin producer
About 100 years ago, Alexander Fleming demonstrated the formation of penicillin in Penicillium chrysogenum. To date, there is no other known producer of the antibiotic penicillin, which has an annual global market value of about six billion Euros.
Combining genes and breeding offspring with new properties
Not only animals and plants, but also many microorganisms such as fungi and algae can reproduce sexually. The advantage: the progenies possess a combination of genes from both mating partners and thus have new properties. Sexual reproduction in fungi is, however, not the rule. Most reproduce via spores which, in the case of moulds, occur as white, green or black deposits on spoiled food. These spores only bear the genes of one parent fungus. “Five years ago we already detected the existence of so-called sex genes in Penicillium chrysogenum“, says Prof. Kück. Now, the researchers have discovered specific environmental conditions in which the fungus actually reproduces sexually. The decisive thing was to breed fungal strains in the dark under oxygen deprivation conditions in a nutrient medium supplemented with the vitamin biotin. The offspring exhibited new properties, both at the molecular level, as well as in their phenotypes.
Results could be applicable to other fungi
Using so-called microarray analysis, the biologists also investigated the activity of all the approximately 12,000 genes of the mould fungus. The result: the sex genes control the activity of biologically relevant genes, for example those for penicillin production. “We presume that the findings can also be applied to other fungi”, says Ulrich Kück, “such as Penicillium citrinum and Aspergillus terreus that produce cholesterol-lowering statins, or Penicillium brevicompactum and Tolypocladium inflatum, which produce immunosuppressives that are used in all organ transplantations”. The researchers conducted the work in the Christian Doppler Laboratory “Biotechnology of Fungi” at the Ruhr-Universität with funding from the Christian Doppler Society (Vienna).
J. Böhm, B. Hoff, C.M. O’Gorman, S. Wolfers, V. Klix, D. Binger, I. Zadra, H. Kürnsteiner, S. Pöggeler, P.S. Dyer, U. Kück (2013): Sexual reproduction and mating-type – mediated strain development in the penicillin-producing fungus Penicillium chrysogenum, PNAS, DOI: 10.1073/pnas.1217943110