Biobased antibiotics from basidios: a case study on the identification and manipulation of a gene cluster involved in pleuromutilin biosynthesis from Clitopilus passeckerianus.

With bacteria becoming resistant to antibiotics, there is a growing need to find new sources of antibiotics. Our work has focussed on the organism Clitopilus passeckerianus which produces a natural antibiotic, pleuromutilin. Recently, a derivative of pleuromutilin, retapamulin (developed by GSK) was approved for use in humans. Clinical trials have demonstrated its efficacy against certain Gram-positive bacteria including MRSA. We have developed all the tools to manipulate this important organism, and will present results on transformation, gene manipulation and enhancement, as well as gene isolation and mapping. These tools have allowed us to isolate the pleuromutilin gene cluster. Using the molecular tools we have been able to identify all genes involved, their roles, and perhaps most importantly, the ability to manipulate to elevate levels of antibiotic production and deliberately alter products produced. These results demonstrate that we are able to manipulate and control the Clitopilus genome. This provides a molecular toolbox which makes it possible to identify and manipulate individual genes of this fungus, and leading to some major new drugs which are not compromised by antibiotic-resistant strains of bacteria. The results will open up major opportunities for other previously intractable systems and antibiotics in fungi.