by Staff Writers
Bochum, Germany (SPX) Jan 10, 2013
For over 100 years, it was assumed that the penicillin-producing mould fungus Penicillium chrysogenum only reproduced asexually through spores. An international research team led by Prof. Dr. Ulrich Kuck and Julia Bohm from the Chair of General and Molecular Botany at the Ruhr-Universitat has now shown for the first time that the fungus also has a sexual cycle, i.e. two "genders".
Through sexual reproduction of P. chrysogenum, the researchers generated fungal strains with new biotechnologically relevant properties - such as high penicillin production without the contaminating chrysogenin.
The team from Bochum, Gottingen, Nottingham (England), Kundl (Austria) and Sandoz GmbH reports in PNAS. The article will be published in this week's Online Early Edition and was selected as a cover story.
Only penicillin producer
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. Kuck.
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
"We presume that the findings can also be applied to other fungi", says Ulrich Kuck, "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-Universitat with funding from the Christian Doppler Society (Vienna).
J. Bohm, B. Hoff, C.M. O'Gorman, S. Wolfers, V. Klix, D. Binger, I. Zadra, H. Kurnsteiner, S. Poggeler, P.S. Dyer, U. Kuck (2013): Sexual reproduction and mating-type - mediated strain development in the penicillin-producing fungus Penicillium chrysogenum, PNAS, DOI: 10.1073/pnas.1217943110
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