Taxonomy and phylogenetic analysis of Aspergillus section nigri isolated from yerba mate in Misiones (Argentina)

Abstract

Members of Aspergillus section Nigri are distributed worldwide and are potentially ochratoxin A producers; some of them are used at industrial level as source of extracellular enzymes and organic acids. The taxonomy of this section comprises one of the most complex and confusing of genus Aspergillus. The objectives of present work were to study the phylogeny of Aspergillus section Nigri and their taxonomy by amplifying ITS1, 5.8S and ITS2 regions. We analyzed 14 strains of Aspergillus section Nigri isolated from different commercial forms of yerba mate, classified according to morphology. Genomic DNA was extracted, the ITS regions were amplified with universal primers ITS1 and ITS4, and the obtained fragments were sequenced. The obtained sequences were aligned and edited to a size of 532bp, to carry out phylogenetic analyses using TNT program. We used 100 RAS+TBR cycles to search for the most parsimonious tree, which was supported by booststrap and Jackknife with 1000 resampled matrices. From the analysis of parsimony, one hundred trees were obtained with 568 steps. Bootstrap and Jackknife analyses exhibited similar topology and minor differences in their supported values, showing that section Nigri is distributed in two general clusters: one composed of A. niger, A. carbonarius and A. heteromorphus clades, and the other composed of A. aculeatus and A. homomorphus clades, separated from different sections of genus Aspergillus.