Project description:Diazotrophs provide the main source of reactive nitrogen to the ocean, sustaining primary productivity and CO2 uptake. Climate change is raising temperatures, decreasing pH and reducing nutrient availability. How microbes respond to these changes is largely unexplained. Similarly, the role of DOM in the growth and survival of certain diazotrophic organisms is poorly understood. Moreover, growing evidence indicates some diazotrophs are capable of utilizing distinct DOM compounds via osmotrophy providing them with additional metabolic plasticity and ecological advantages compared to other non-diazotrophic microbes. We aimed to understand how osmotrophy could modify carbon uptake and alleviate energy stress in diazotrophs under ongoing climate change perturbations. We hypothesized that Crocosphaera preferentially uses DOM when labile as a carbon source in present pH conditions, as compared to future more acidic scenarios with higher access to inorganic carbon. Alternatively, the lower pH may cause Crocosphaera to be energy limited when trying to maintain intracellular homeostasis which would favour DOM uptake as an extra source of energy.
Project description:Transcriptome response of the yeasts C. glabrata and S. cerevisiae treated by an antifungal agent, benomyl Keywords: time course; stress response
Project description:Xylanolytic enzyme systems in ascomycetous yeasts remain underexplored, despite the presence of yeasts in various xylan-rich ecological niches. In this study, we investigated the secreted xylanolytic machineries of three Blastobotrys species—B. mokoenaii, B. illinoisensis, and B. malaysiensis—by integrating genome annotation, bioinformatics, and secretome analyses of cultures grown on beechwood glucuronoxylan. Our findings demonstrate that these yeasts effectively hydrolyze xylan through the secretion of xylanases from the glycoside hydrolase (GH) family 11, which play a central role in cleaving the xylan backbone. Additionally, the yeasts produce a diverse array of other CAZymes, including members of GH families 3, 5, 30_7, and 67, with putative roles in xylan degradation. We also report on the heterologous expression and functional characterization of the GH30_7 xylanase BmXyn30A from B. mokoenaii, which exhibits both glucoronoxylanase and xylobiohydrolase activities. Distinct differences were observed in the xylooligosaccharide profiles generated by BmXyn30A compared to the previously characterized GH11 xylanase BmXyn11A. Furthermore, we demonstrate the synergistic effects between BmXyn30A and BmXyn11A during the hydrolysis of beechwood glucuronoxylan, where the enzymes exhibited complementary roles that enhanced the deconstruction of this complex hemicellulose substrate. These findings broaden our understanding of the xylanolytic systems in yeasts and underscore the potential of Blastobotrys species as cell factories and natural xylanase producers. The enzymes they produce hold promise for biorefining applications, enabling efficient utilization of renewable, xylan-rich plant biomass resources.
Project description:Transcriptome response of the yeasts C. glabrata and S. cerevisiae treated by an antifungal agent, benomyl Keywords: time course; stress response We performed microarray analyses of the transcriptome response of the yeasts Candida glabrata and Saccharomyces cerevisiae, treated by an antifungal agent, benomyl. The C. glabrata cells were submitted to 20 μg/mL of benomyl for 2, 4, 10, 20, 40 and 80 minutes. The labelled cDNA from treated cells were competitively hybridized on microarrays versus cDNA from mock treated cells.