Diversity and delimitation of Rhizopus microsporus

Rhizopus microsporus has been used for centuries in the production of oriental fermented foods,but the species is also known as a toxin producer and from severe human infections.To study the diversity and species delimitation of Rhizopus microsporus,48 isolates from the reference collection of the CBS-KNAW Fungal Biodiversity Centre,comprising nine environmental,ten clinical,and 23 foodborne strains,in addition to six strains from unknown sources and representing all existing varieties of the species,were examined.Sequence diversity was based on the internal transcribed spacer(ITS),and on a part of the actin(ACT)and translation elongation factor 1-α(TEF)genes.Differences in physiological properties were assessed including temperature relationships.Spore morphology was studied,mating type tests were performed,and MALDI-ToF profiles were generated.Clinical and food-associated strains as well as members of different varieties mated successfully and consequently they belong to a single biological species.Molecular differences did not match with any other parameter investigated.Based on these results the varieties of Rhizopus microsporus are reduced to synonyms.

Taxonomy of Ochroconis, genus including opportunistic pathogens on humans and animals

The genus Ochroconis(Sympoventuriaceae,Venturiales)is revised and currently contains 13 species for which the phylogenetic position has been determined using multilocus sequencing.The older generic name Scolecobasidium is considered to be of doubtful identity because the type specimen is ambiguous.Within the Ochroconis lineage,phylogenetic distances of all markers analyzed are exceptionally large,both between and within species.A new genus Verruconis is proposed for the neurotropic opportunist Ochroconis gallopava.Species accepted within the lineages are keyed out on the basis of phenotypic characters.Main ecological traits within each species are discussed.Verruconis species are thermophilic and one of them is an important agent of infection in the brain,while Ochroconis is mesophilic,several species causing infections in cold-blooded animals.

Cyphellophora and its relatives in Phialophora: biodiversity and possible role in human infection

Cyphellophora is a genus of black yeast-like fungi characterised by having simple phialides with multiseptate,curved conidia.Judging from SSU and LSU data,Cyphellophora was found to be located in a well-supported clade within the Chaetothyriales comprising a number of species occurring on human skin and nail.Cyphellophora is phylogenetically close to Phialophora europaea,P.reptans and P.oxyspora,though morphologically these species produce singlecelled phialoconidia rather than multiseptate ones.Pseudomicrodochium suttonii and P.fusarioides have dark colonies and phylogenetically fit in with Cyphellophora;the type species of Pseudomicrodochium,P.aciculare,has similar,septate conidia but has a hyaline thallus.In the present study,multilocus phylogenetic analyses were combined with morphology and physiology.Sequences of the internal transcribed spacer region,the DNA dependent RNA polymerase II largest subunit and the partial beta tubulin gene were analysed for a set of 30 strains.Two novel species,Cyphellophora pauciseptata and Phialophora ambigua were discovered.Cyphellophora eucalypti was reduced to synonymy of C.guyanensis.The role of the studied fungi between colonization and infection of human skin was discussed.Putative virulence factors for these black yeast-like fungi were hypothesized to be the ability to assimilate monoaromatic hydrocarbons,to produce melanin pigments,and to tolerate the temperature of epidermal human skin.

Multilocus analysis of the Exophiala jeanselmei clade containing black yeasts involved in opportunistic disease in humans

To confirm species delimitations in the‘jeanselmeiclade’in the Chaetothyriales,four independent markers were analysed,and phylogenetic trees were reconstructed using different algorithms.Reproductive isolation within the complex and reproductive modes in the species involved were determined,in order to explore specific borderlines using Genealogical Concordance Phylogenetic Species Recognition(GCPSR).Sequences of the Internal Transcribed Spacer(ITS),partial Translation Elongation Factor 1-α(TEF1),β-Tubulin(BT2),and Actin(ACT1)genes were analysed for a set of 81 strains.Phylogenetic reconstruction was performed using neighbour-joining(NJ),maximum parsimony(MP),maximum likelihood(ML)and Bayesian analysis(BA)to evaluate the concordance of topologies obtained under different optimization criteria.Incongruence among lineages was detected by Partition Homogeneity Test(PHT).Most Exophiala species analysed in this study seemed to be preponderantly clonal.A group of species around Exophiala spinifera showed a tendency toward human pathogenicity,whereas species around E.bergeri were often associated with environments rich in hydrocarbons.Though the tree topologies were not completely identical when different algorithms were used,the four gene lineages were nearly congruent and the trees of the combined multilocus data set did not provide more phylogenetic information than those of separate data sets.ITS data are sufficient for identification of species in the‘jeanselmei-clade’.