Project description:The type species of the genus Debaryomyces, Debaryomyces hansenii, is a highly heterogeneous species. It has been isolated from a large diversity of natural sources including fruit, air, water, soil, but most frequently from processed food products. The species delineation of this yeast species urgently needs clarification. The heterogeneity in taxonomic characteristics has resulted in the description of varieties linked to D. hansenii. The aim of this study was to re-examine and classify D. hansenii using a polyphasic approach. A total of 65 D.hansenii isolates were examined, 57 representing the variety hansenii and nine the variety fabryi. The selection of strains for DNA reassociation and phylogenetic analysis was based on polymerase chain reaction mediated fingerprints using four mini- and microsatellite-specific primers. The discriminating power of growth at 35 degrees C and 37 degrees C was re-examined and ascospore production was observed. DNA reassociations and phylogenetic analyses were performed on selected isolates from each of the clusters obtained from the DNA fingerprint analyses. The data indicated the presence of three distinct species within the D. hansenii group, which were represented by type strains of former species and that are proposed to be reinstated: D. hansenii (CBS 767(T) = MUCL 49680(T)), D. fabryi (CBS 789(T) = MUCL 49731(T)) and D. subglobosus (CBS 792(T) = MUCL 49732(T)).
Project description:If life exists on Mars, it would face several challenges including the presence of perchlorates, which destabilize biomacromolecules by inducing chaotropic stress. However, little is known about perchlorate toxicity for microorganism on the cellular level. Here we present a proteomic investigation on the perchlorate-specific stress responses of the halotolerant yeast Debaryomyces hansenii and compare these to generally known salt stress adaptations. We found that the responses to NaCl and NaClO4-induced stresses share many common metabolic features, e.g., signaling pathways, elevated energy metabolism, or osmolyte biosynthesis. However, several new perchlorate-specific stress responses could be identified, such as protein glycosylation and cell wall remodulations, presumably in order to stabilize protein structures and the cell envelope. These stress responses would also be relevant for life on Mars, which - given the environmental conditions - likely developed chaotropic defense strategies such as stabilized confirmations of biomacromolecules and the formation of cell clusters.
Project description:We found that the fungus, Debaryomyces hansenii (D. hansenii), is enriched in inflamed intestinal tissue from patients of Crohn's disease and its administration to mice impairs colonic wound healing in multiple models of colonic injury and repair. To understand the mechanism, we isolated bone marrow derived macrophages from mice and stimulated them in vitro with a pure isolate of D. hansenii. Total RNA was isolated at multiple time points and assayed for transcriptomic analysis.
Project description:The mechanisms of cellular and molecular adaptation of fungi to salinity have been commonly drawn from halotolerant strains, although some exceptions in basidiomycete fungi can be found. These studies have been conducted in settings where cells are subjected to stress, either hypo or hyperosmotic, which can be a confounding factor in describing physiological mechanisms related to salinity. Here, we have studied transcriptomic changes in Aspergillus sydowii, a halophilic species, when growing in three different salinity conditions (No salt, 0.5M and 2.0M NaCl). In this fungus salinity related responses occur under high salinity (2.0M NaCl) and not when cultured under optimal conditions (0.5M NaCl), suggesting that in this species, most of the mechanisms described for halophilic growth are a consequence of saline stress response and not an adaptation to saline conditions.
