Two new lipid-dependent Malassezia species from domestic animals

During a study on the occurrence of lipid-dependent Malassezia spp. in domestic animals, some atypical strains, phylogenetically related to Malassezia sympodialis Simmons et Guého, were shown to represent novel species. In this study, we describe two new taxa, Malassezia caprae sp. nov. (type strain MA383=CBS 10434), isolated mainly from goats, and Malassezia equina sp. nov. (type strain MA146=CBS 9969), isolated mainly from horses, including their morphological and physiological characteristics. The validation of these new taxa is further supported by analysis of the D1/D2 regions of the 26S rRNA gene, the ITS1-5.8S-ITS2 rRNA, the RNA polymerase subunit 1 and chitin synthase nucleotide sequences, and the amplified fragment length polymorphism patterns, which were all consistent in separating these new species from the other species of the genus, and those of the M. sympodialis species cluster, specifically

Functional diversity in Dichomitus squalens monokaryons

Abstract Dichomitus squalens is a white-rot fungus that colonizes and grows mainly on softwood and is commonly found in the northern parts of Europe, North America, and Asia. We analyzed the genetic and physiological diversity of eight D. squalens monokaryons derived from a single dikaryon. In addition, an unrelated dikaryon and a newly established dikaryon from two of the studied monokaryons were included. Both growth and lignocellulose acting enzyme profiles were highly variable between the studied monokaryotic and dikaryotic strains, demonstrating a high level of diversity within the species

Multiple hybridization events punctuate the evolutionary trajectory of malassezia furfur

Malassezia species are important fungal skin commensals and are part of the normal microbiota of humans and other animals. However, under certain circumstances these fungi can also display a pathogenic behavior. For example, Malassezia furfur is a common commensal of human skin and yet is often responsible for skin disorders but also systemic infections. Comparative genomics analysis of M. furfur revealed that some isolates have a hybrid origin, similar to several other recently described hybrid fungal pathogens. Because hybrid species exhibit genomic plasticity that can impact phenotypes, we sought to elucidate the genomic evolution and phenotypic characteristics of M. furfur hybrids in comparison to their parental lineages. To this end, we performed a comparative genomics analysis between hybrid strains and their presumptive parental lineages and assessed phenotypic characteristics. Our results provide evidence that at least two distinct hybridization events occurred between the same parental lineages and that the parental strains may have originally been hybrids themselves. Analysis of the mating-type locus reveals that M. furfur has a pseudobipolar mating system and provides evidence that after sexual liaisons of mating compatible cells, hybridization involved cell-cell fusion leading to a diploid/aneuploid state. This study provides new insights into the evolutionary trajectory of M. furfur and contributes with valuable genomic resources for future pathogenicity studies. IMPORTANCE Malassezia furfur is a common commensal member of human/animal microbiota that is also associated with several pathogenic states. Recent studies report involvement of Malassezia species in Crohn’s disease, a type of inflammatory bowel disease, pancreatic cancer progression, and exacerbation of cystic fibrosis. A recent genomics analysis of M. furfur revealed the existence of hybrid isolates and identified their putative parental lineages. In this study, we explored the genomic and phenotypic features of these hybrids in comparison to their putative parental lineages. Our results revealed the existence of a pseudobipolar mating system in this species and showed evidence for the occurrence of multiple hybridization events in the evolutionary trajectory of M. furfur. These findings significantly advance our understanding of the evolution of this commensal microbe and are relevant for future studies exploring the role of hybridization in the adaptation to new niches or environments, including the emergence of pathogenicity.We thank Timothy James for reviewing our manuscript, Bart Kraak for some exploratory PCR and microscopy work, Simon Denil for assistance with the initial bioinformatics assessment of strain CBS1878, Claudia Cafarchia for providing strain CD866, and Marina Marcet-Houben for helpful discussions on the bioinformatics analyses. This study was supported by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement H2020-MSCA-ITN-2014-642095. The T.G. group also acknowledges support from the Spanish Ministry of Economy, Industry, and Competitiveness (MEIC) for the EMBL partnership, and grants Centro de Excelencia Severo Ochoa 2013-2017 SEV-2012-0208 and BFU2015-67107 cofounded by European Regional Development Fund (ERDF); from the CERCA Program/Generalitat de Catalunya; from the Catalan Research Agency (AGAUR) SGR857; and from grants from the European Union’s Horizon 2020 research and innovation program under the grant agreement ERC-2016-724173. T.G. also receives support from an INB grant (PT17/0009/0023—ISCIII-SGEFI/ERDF). G.I. and J.H. were supported by NIH/NIAID R37 award AI39115-24 and R01 award AI50113-16A1. J.H. is fellow and codirector of the CIFAR program Fungal Kingdom: Threats and Opportunities. T.L.D. was supported by the Skin Research Institute of Singapore Fund (IAF-PP H17/01/a0/004).Peer ReviewedPostprint (published version

Da Vinci’s yeast : Blastobotrys davincii f.a., sp. nov.

A new species of the yeast genus Blastobotrys was discovered during a worldwide survey of culturable xerophilic fungi in house dust. Several culture dependent and independent studies from around the world detected the same species from a wide range of substrates including indoor air, cave wall paintings, bats, mummies, and the iconic self-portrait of Leonardo da Vinci from ca 1512. However, none of these studies identified their strains, clones or OTUs as Blastobotrys. We introduce the new species as Blastobotrys davincii f.a., sp. nov. (holotype CBS H-24879) and delineate it from other species using morphological, phylogenetic, and physiological characters. The new species of asexually (anamorphic) budding yeast is classified in Trichomonascaceae and forms a clade along with its associated sexual state genus Trichomonascus. Despite the decade-old requirement to use a single generic name for fungi, both names are still used. Selection of the preferred name awaits a formal nomenclatural proposal. We present arguments for adopting Blastobotrys over Trichomonascus and introduce four new combinations as Blastobotrys allociferrii (≡ Candida allociferrii), B. fungorum (≡ Sporothrix fungorum), B. mucifer (≡ Candida mucifera) and Blastobotrys vanleenenianus (≡ Trichomonascus vanleenenianus). We provide a nomenclatural review and an accepted species list for the 37 accepted species in the Blastobotrys/Trichomonascus clade. Finally, we discuss the identity of the DNA clones detected on the da Vinci portrait, and the importance of using appropriate media to isolate xerophilic or halophilic fungi.The Alfred P. Sloan Foundation Program on the Microbiology of the Built Environment.https://onlinelibrary.wiley.com/journal/10970061hj2022BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant Patholog

Ablation of CD8 alpha(+) dendritic cell mediated cross-presentation does not impact atherosclerosis in hyperlipidemic mice

Clinical complications of atherosclerosis are almost exclusively linked to destabilization of the atherosclerotic plaque. Batf3-dependent dendritic cells specialize in cross-presentation of necrotic tissue-derived epitopes to directly activate cytolytic CD8 Tcells. The mature plaque (necrotic, containing dendritic cells and CD8 Tcells) could offer the ideal environment for cross-presentation, resulting in cytotoxic immunity and plaque destabilization. Ldlr(-/-) mice were transplanted with batf3(-/-) or wt bone marrow and put on a western type diet. Hematopoietic batf3 deficiency sharply decreased CD8 alpha(+) DC numbers in spleen and lymph nodes (>80%;P < 0, 001). Concordantly, batf3(-/-) chimeras had a 75% reduction in OT-I cross-priming capacity in vivo. Batf3(-/-) chimeric mice did not show lower Tcell or other leukocyte subset numbers. Despite dampened cross-presentation capacity, batf3(-/-) chimeras had equal atherosclerosis burden in aortic arch and root. Likewise, batf3(-/-) chimeras and wt mice revealed no differences in parameters of plaque stability: plaque Tcell infiltration, cell death, collagen composition, and macrophage and vascular smooth muscle cell content were unchanged. These results show that CD8 alpha(+) DC loss in hyperlipidemic mice profoundly reduces cross-priming ability, nevertheless it does not influence lesion development. Taken together, we clearly demonstrate that CD8 alpha(+) DC-mediated cross-presentation does not significantly contribute to atherosclerotic plaque formation and stability

Selective C-Rel Activation via Malt1 Controls Anti-Fungal TH-17 Immunity by Dectin-1 and Dectin-2

C-type lectins dectin-1 and dectin-2 on dendritic cells elicit protective immunity against fungal infections through induction of TH1 and TH-17 cellular responses. Fungal recognition by dectin-1 on human dendritic cells engages the CARD9-Bcl10-Malt1 module to activate NF-κB. Here we demonstrate that Malt1 recruitment is pivotal to TH-17 immunity by selective activation of NF-κB subunit c-Rel, which induces expression of TH-17-polarizing cytokines IL-1β and IL-23p19. Malt1 inhibition abrogates c-Rel activation and TH-17 immunity to Candida species. We found that Malt1-mediated activation of c-Rel is similarly essential to induction of TH-17-polarizing cytokines by dectin-2. Whereas dectin-1 activates all NF-κB subunits, dectin-2 selectively activates c-Rel, signifying a specialized TH-17-enhancing function for dectin-2 in anti-fungal immunity by human dendritic cells. Thus, dectin-1 and dectin-2 control adaptive TH-17 immunity to fungi via Malt1-dependent activation of c-Rel