PNNL

Abstract

Aspergillus section Nigri comprises filamentous fungi relevant to biomedicine, bioenergy, health, and biotechnology. In order to learn more about fungal speciation, as well as potential for applications in biotechnology and biomedicine, we sequenced 23 genomes de novo, forming a full genome compendium for the section (26 species), as well as six A. niger isolates. This allowed us to quantify both inter- and intra-species genomic variation. We further predicted 17,903 CAZymes and 2,717 secondary metabolite gene clusters, which we condensed into 455 distinct families corresponding to compound classes, 49% of which are only found in single species. We performed metabolomics and genetic engineering to correlate genotypes to phenotypes, as demonstrated for the metabolite aurasperone, and by heterologous transfer of citrate production to A. nidulans. Experimental and computational analyses all supported a role in speciation for secondary metabolism and regulators and allowed us to propose a three-step model for fungal speciation.