Abstract The fungal-algal-bacterial (FAB) consortium composed of Euglena mutabilis, Talaromyces, and Acidiphilium acidophilum is a natural acid-tolerant assemblage whose heavy metal handling may depend on interspecies cooperation rather than a single-organism uptake alone. Here, glucose was used as a simplified laboratory model of labile carbon availability to test whether carbon input reorganizes consortium structure and stress responses under CdCl2 exposure. Glucose supplementation promoted fungal hyphal development, more extensive visible bacterial colonization, pronounced flocculation, and higher Euglena cell densities under CdCl2 stress. CdCl2 accumulation relative to Euglena cell abundance increased over time in all CdCl2-treated cultures but did not differ significantly among glucose treatments. Hormone profiling revealed distinct extracellular responses under glucose + CdCl2, including elevated bioactive trans-Zeatin (tZ), gibberellin GA7, methyl-thiolated cytokinins, and jasmonic acid, consistent with coordinated consortium-level signalling under metal stress. Scanning electron microscopy provided visual evidence of the FAB physically restructuring when grown in glucose, while transmission electron microscopy (TEM) identified previously uncharacterized electron-dense intravacuole bodies within E. mutabilis, although their identity could not be determined. Together, these findings show that glucose availability reorganizes structural and biochemical signalling of the FAB consortium and is associated with changes in consortium organization and physiological responses under heavy metal stress. They also highlight coordinated structural and biochemical responses associated with consortium persistence under acidic, metal-rich conditions and identify directions for future mechanistic investigations.
Abstract Komagataella phaffii (formerly Pichia pastoris) is a popular host for protein production, enabling their targeted application and in-depth study. Among relevant targets are gluten proteins, which are essential for cereal-based food properties, but can also trigger immune reactions such as coeliac disease. Previously, production of rye (Secale cereale) prolamin 75k γ-secalin in K. phaffii was shown to yield the highest titres with the native secretion signal compared to co- and post-translational signals commonly used for enhanced production. Here, we compared the host’s transcriptomic response to 75k γ-secalin expressed with the native signal (gSec) or a chimeric OST1-pre-MATα-pro leader (S4gSec) against a non-producing null mutant. Production of the native 75k γ-secalin showed minimal impact; whereas stress-, amino acid transport-, and flocculation-related pathways were upregulated in K. phaffii S4gSec. Transcriptome investigation yielded GCN4 as potential marker for transcriptomic stress monitoring during heterologous protein production. Despite K. phaffii’s significance as protein production host, many of its genes are only putatively annotated. Of the 31 (gSec) and 349 (S4gSec) differentially expressed genes, 29% and 59.3% are putative, respectively. This study presents a tentative in silico characterization of these genes, highlighting the importance of continued functional characterization of the K. phaffii genome.
Abstract Malassezia furfur is fungi associated with various diseases; however, the mechanisms underlying its pathogenicity and the relationship between probiotics and fungi remain largely unknown. In the present study, Caenorhabditis elegans was used as the model host to evaluate M. furfur pathogenicity. Additionally, effects of lactic acid bacteria against M. furfur pathogenicity were evaluated. Compared to Escherichia coli OP50 (OP, control), both live and heat-killed M. furfur reduced the lifespan and body size of C. elegans, although heat-killed M. furfur was less effective than live M. furfur in lifespan shortening. Furthermore, unlike heat-killed M. furfur, live M. furfur disrupted the nematode intestinal barrier. Loss-of-function mutants of nsy-1 and sek-1, which encode components of the MAPK signaling pathway, were susceptible to M. furfur, suggesting their involvement in the defense against M. furfur infection. Expression of genes involved in host defense and of those coding for C-type lectin domain-containing proteins and antimicrobial peptides was upregulated in M. furfur-infected C. elegans. Lacticaseibacillus rhamnosus (LR) significantly ameliorated lifespan shortening and body size reduction in M. furfur-infected C. elegans and protected against intestinal barrier disruption, suggesting that LR protects nematodes from M. furfur virulence. This study highlights M. furfur pathogenicity and intestinal barrier disruptive ability in C. elegans and suggests that the M. furfur virulence is partially attenuated by LR.
Abstract Despite their ecological importance and protected status, the diversity, host associations, and evolutionary relationships of coccidia infecting shrews (Eulipotyphla: Soricidae) remain poorly understood. In particular, the extent of host specificity, the occurrence of host-switching events, and the relationships among coccidian lineages infecting different shrew hosts remain unclear. Here, we investigated coccidian diversity and phylogenetic relationships across several shrew genera and species to clarify parasite–host associations and provide new insights into the evolutionary processes shaping coccidian diversity in shrews. Fecal samples from 188 shrews representing the genera Crocidura, Neomys, Sorex, and Suncus, collected across multiple localities in Europe and two localities in Asia, were examined. Coccidia were detected in one quarter of the samples, generally at low intensities. Phylogenetic analyses based on partial COX1, COX3, and 18S rRNA sequences identified four distinct clusters: three were host-specific (two associated with Crocidura and one with Neomys), whereas one lineage was shared among Crocidura, Neomys, and Sorex. Two Isospora sequences from Sorex araneus clustered with isosporans previously reported from moles. No clear geographic structuring was observed, and the phylogenetic structure also did not mirror the observed morphological characters. The results indicate that host switching and subsequent repeated dispersal occur in eimerians of shrews, suggesting that these processes may be more widespread across small-mammal hosts than previously recognized. The findings expand current knowledge on coccidian diversity in shrews and provide new insights into the host specificity, ecology, and evolutionary dynamics of the parasitic protists.
The Altiplano-Puna plateau lies at ∼4000 m above sea level in the volcanic Andes cordillera. Together with the adjacent Atacama Desert, it forms one of the most hyperarid regions on the planet. Wetlands are rare, influenced by hydrothermalism and, due to high evaporation rates, dominated by saline lakes and ephemeral ponds associated with salt flats (collectively called salares). Long thought to be lifeless, these environments host microbial ecosystems adapted to extreme conditions in terms of temperature, pH, salinity, ultraviolet radiation, and high concentrations of metals and metalloids, including arsenic, copper, and lithium. Climate change and mining activities, notably lithium extraction for "green energies," are causing the desiccation of these systems. Their microbial biodiversity risks being lost before it is studied. In this review, we highlight three major active research areas that provide added value to Atacama-Altiplano microbiomes beyond their intrinsic ecosystemic importance, identifying knowledge gaps and future research trends at the fundamental-applied science interface. First, studying these poorly known microbes may help us understand and exploit molecular adaptations to extreme conditions and better define the limits of life, with implications for astrobiology. Second, Atacama-Altiplano phototrophic microbial mats and microbialites can be suitable geochemical and biological analogs of ancient microbial ecosystems and reveal ecological and evolutionary aspects of paleoenvironments. Third, these microbial ecosystems represent an untapped reservoir of robust enzymes for biocatalysis, as well as environmentally friendly solutions for sustainable copper and lithium mining, recycling, and bioremediation processes. Collectively, these arguments justify the urgency of prioritizing these unique microbial ecosystems as conservation targets.
