Bed of oatmeal proves sexy for penicillin fungus

U. NOTTINGHAM (UK) — Knowing what gets a seemingly asexual fungus turned on could lead to cheaper penicillin.

The researchers found that sexual reproduction could be induced in Penicillium chrysogenum when strains were mated in the dark on oatmeal with a vitamin supplement.

The research also demonstrates that sexual crosses can be used to develop new strains with improved industrial characteristics.


“We now have a valuable tool for creating new strains of P. chrysogenum with increased penicillin production. This will make it cheaper to produce penicillin, as using more efficient strains will lower production costs,” says Paul Dyer, an expert in the sexual development and genetics of filamentous fungi at the University of Nottingham.

“Our method might also be used to help discover hidden sexual cycles in other economically important fungi that are assumed to be exclusively asexual.”

The researchers show that the sexual cycle could be used for strain development purposes by producing offspring with new combinations of important biotechnological properties for penicillin production, such as the removal of chrysogenin, a contaminating substance produced by the fungus.

As reported in the Proceedings of the National Academy of Sciences, the team also discovered that mating-type genes, which control sex in fungi, have additional roles regulating other developmental processes of biotechnological relevance.

Fungi are used to produce many important pharmaceutical products including statins and antibiotics, and most species involved have long been considered to be asexual.

But the present findings suggest that sexual reproduction could be triggered in other supposedly asexual fungi if the mating-type genes and correct growth conditions can be identified.

Penicillium chrysogenum first came to attention in 1928 when Sir Alexander Fleming made the fortuitous discovery that a Penicillium mold, which had contaminated a bacterial culture, was able to inhibit the growth of nearby bacteria by releasing penicillin into its surroundings.

Over 10 years later two scientists, Ernst Chain and Howard Florey, were the first to grow the fungus in large quantities to generate enough penicillin to treat patients.

These events heralded the start of the antibiotic era, which has been one of the most important advances in medicine. Fleming, Chain, and Florey later shared the Nobel Prize in physiology/medicine. Since then it has only been possible to develop strains of P. chrysogenum with elevated production of penicillin by conventional mutagenesis.

Professors Ulrich Kück and Stefanie Pöggeler from Germany, Paul Dyer, and scientists from Sandoz GmbH lead the research, which was funded by the Christian Doppler Society of Austria and The Wellcome Trust.

Source: University of Nottingham