Polyphasic taxonomic revision of the Mucoraceae (Mucoromycotina)

• Applicant: Dr. Grit Walther
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 252281572

The Mucoraceae (Mucorales, Mucoromycotina) belong to a phylogenetically ancient group of lower fungi that until recently was referred to as zygomycetes. They mainly include fast growing saprotrophic fungi that are pioneers on all kinds of wet organic materials and a permanent part of the human environment. Several species of the Mucoraceae are applied for the biotransformation and the production of organic acids and enzymes. Since centuries they have been used for the fermentation of traditional Asian and African food. On the other hand Mucoraceae may cause life-threatening infections (mucormycoses) mostly in patients with impaired immunity. In the last century an alarming increase of mucormycoses has been noticed probably due to the gain of risk factors such as diabetes, the long-term use of steroids or transplantations. Currently mucormycoses are the third most frequent invasive fungal infections. An early and reliable diagnosis is crucial for a positive outcome because these infections generally have a dramatic course and a high rate of mortality. However, the current classification of this family is highly artificial and deficient hampering reliable DNA-based diagnostics. Mucor the species richest genus of the Mucoraceae is polyphyletic and several morphospecies form species complexes with unclear species boundaries. Therefore the goal of this project is a modern taxonomic revision of the Mucoraceae and the improvement of their diagnostics. The new classification will be based on multi-locus phylogenies, morphological and physiological characters as well as mating tests. New phylogenetic markers selected by genome analyses will be used for multi-locus phylogenies because the conventional phylogenetic markers for fungi are known to have paralogues in the Mucoraceae. Beside the classical morphological characters the phenotypic study will include characters with relevance for pathogenicity such as thermotolerance and dimorphism. For the first time the yeast state will be included in a taxonomic study within the Mucorales. Mating tests will be performed in order to obtain indications of biological species boundaries. The new taxonomic concepts will be applied in a publicly accessible ITS database to overcome the deficiencies of the molecular species identification using the BLAST search of GenBank and to allow a reliable identification by everybody without the need of expertise. Furthermore MALDI-ToF profiles will be generated for all clinically relevant species and their sibling species in order to improve also the non-DNA-based diagnostics. The phenotypic taxonomic findings will be implemented in a key that will allow clinical routine labs without access to molecular techniques a correct identification of pathogenic Mucorales. The data of dimorphism and thermotolerance will provide a risk assessment concerning the pathogenic potential of the Mucoraceae species.

• DFG Programme: Research Grants