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BackgroundCost-effective production of biofuels from lignocellulose requires the fermentation of D-xylose. Many yeast species within and closely related to the genera Spathaspora and Scheffersomyces (both of the order Serinales) natively assimilate and ferment xylose. Other species consume xylose inefficiently, leading to extracellular accumulation of xylitol. Xylitol excretion is thought to be due to the different cofactor requirements of the first two steps of xylose metabolism. Xylose reductase (XR) generally uses NADPH to reduce xylose to xylitol, while xylitol dehydrogenase (XDH) generally uses NAD+ to oxidize xylitol to xylulose, creating an imbalanced redox pathway. This imbalance is thought to be particularly consequential in hypoxic or anoxic environments.ResultsWe screened the growth of xylose-fermenting yeast species in high and moderate aeration and identified both ethanol producers and xylitol producers. Selected species were further characterized for their XR and XDH cofactor preferences by enzyme assays and gene expression patterns by RNA-Seq. Our data revealed that xylose metabolism is more redox balanced in some species, but it is strongly affected by oxygen levels. Under high aeration, most species switched from ethanol production to xylitol accumulation, despite the availability of ample oxygen to accept electrons from NADH. This switch was followed by decreases in enzyme activity and the expression of genes related to xylose metabolism, suggesting that bottlenecks in xylose fermentation are not always due to cofactor preferences. Finally, we expressed XYL genes from multiple Scheffersomyces species in a strain of Saccharomyces cerevisiae. Recombinant S. cerevisiae expressing XYL1 from Scheffersomyces xylosifermentans, which encodes an XR without a cofactor preference, showed improved anaerobic growth on xylose as the primary carbon source compared to S. cerevisiae strain expressing XYL genes from Scheffersomyces stipitis.ConclusionCollectively, our data do not support the hypothesis that xylitol accumulation occurs primarily due to differences in cofactor preferences between xylose reductase and xylitol dehydrogenase; instead, gene expression plays a major role in response to oxygen levels. We have also identified the yeast Sc. xylosifermentans as a potential source for genes that can be engineered into S. cerevisiae to improve xylose fermentation and biofuel production.

The paper presents the results of a survey (n = 279) conducted with the students of an undergraduate design course. The questionnaire inquired design students' preferences regarding educational formats (distance, in-person, or combination of both); the questionnaire further explored the issue by comparing between four types of classes (project, drawing, theoretical-practical, and theoretical) and by establishing comparisons between the students' enrolment year. The main results reveal that design students prefer in-person formats, and preference for in-person educational formats increases regarding "project-based" or "drawing" type of classes; what is more, preference for in-person educational formats is appears to be higher in second and third-year students than in first-year ones. These results have implications for design education: a direct transfer of the typical design educational format to a distance setting may be misguided and design education may require specific formats (distance or otherwise) to offer a satisfactory pedagogical experience to its students.

The unambiguous application of fungal names is important to communicate scientific findings. Names are critical for (clinical) diagnostics, legal compliance, and regulatory controls, such as biosafety, food security, quarantine regulations, and industrial applications. Consequently, the stability of the taxonomic system and the traceability of nomenclatural changes is crucial for a broad range of users and taxonomists. The unambiguous application of names is assured by the preservation of nomenclatural history and the physical organisms representing a name. Fungi are extremely diverse in terms of ecology, lifestyle, and methods of study. Predominantly unicellular fungi known as yeasts are usually investigated as living cultures. Methods to characterize yeasts include physiological (growth) tests and experiments to induce a sexual morph; both methods require viable cultures. Thus, the preservation and availability of viable reference cultures are important, and cultures representing reference material are cited in species descriptions. Historical surveys revealed drawbacks and inconsistencies between past practices and modern requirements as stated in the International Code of Nomenclature for Algae, Fungi, and Plants (ICNafp). Improper typification of yeasts is a common problem, resulting in a large number invalid yeast species names. With this opinion letter, we address the problem that culturable microorganisms, notably some fungi and algae, require specific provisions under the ICNafp. We use yeasts as a prominent example of fungi known from cultures. But viable type material is important not only for yeasts, but also for other cultivable Fungi that are characterized by particular morphological structures (a specific type of spores), growth properties, and secondary metabolites. We summarize potential proposals which, in our opinion, will improve the stability of fungal names, in particular by protecting those names for which the reference material can be traced back to the original isolate.

Short-term study abroad experiences are the most common type of undergraduate study abroad programs offered by universities in the United States. However, and to the best of our knowledge, little empirical research exists on students' learning outcomes following their participation in a short-term program using an integrated research praxis. To address this, we structured an international embedded program in Costa Rica and Panama which allowed students to engage in authentic research experiences topically centered in ecology and service-learning activities in conservation biology. Mixed methods analyses on data generated from the assessment of students (n=54) in three cohorts, revealed students' gains (both positive and negative) in specific scientific skills and knowledge domains in both the fields of ecology and conservation biology, as well as interest in doing further field research, perceptions of authentic international field research, appreciation of the value of biodiversity, advocacy, and future actions as conservationists and informed citizens (global citizenship).

Biotechnological processes are essential for developing economies that aim to stand out in future markets. The use of bioreactors is one of the most important unit operations of biotechnological processes, and real-time monitoring of bioreactors is essential to ensure precise bioprocess control. This review presents different types of bioreactors, sensors, and applications in other sectors. Bioreactors, controlled systems for cultivating microorganisms and cells, are essential tools in various fields, from scientific research to industrial production. The use of a variety of sensors is critical for accurate, real-time monitoring, early problem detection, reproducibility, cost reduction, and increased efficiency. These benefits are being realized in numerous applications, including biofuel production, bioremediation and leaching processes, tissue engineering, and drug manufacturing. Innovations in bioreactor technology are expanding opportunities for a more sustainable and healthier future. By developing new types of bioreactors, integrating advanced sensors, and exploring promising applications, bioreactors are playing a key role in addressing global challenges and sustainably advancing science and technology. [ABSTRACT FROM AUTHOR]

Chlorothalonil (CTL) is a pesticide widely used in Brazil, yet its mutagenic potential is not fully determined. Thus, we assessed the mutagenicity of CTL and its bioactivation metabolites using the somatic mutation and recombination test (SMART) in Drosophila melanogaster, by exposing individuals, with basal and high bioactivation capacities (standard and high bioactivation cross offspring, respectively), from third instar larval to early adult fly stages, to CTL‐contaminated substrate (0.25, 1, 10 or 20 μM). This substrate served as food and as physical medium. Increased frequency of large single spots in standard cross flies' wings exposed to 0.25 μM indicates that, if CTL is genotoxic, it may affect Drosophila at early life stages. Since the total spot frequency did not change, CTL cannot be considered mutagenic in SMART. The same long‐term exposure design was performed to test whether CTL induces oxidative imbalance in flies with basal (wild‐type, WT) or high bioactivation (ORR strain) levels. CTL did not alter reactive oxygen species and antioxidant capacity against peroxyl radicals levels in adult flies. However, lipid peroxidation (LPO) levels were increased in WT male flies exposed to 1 μM CTL. SMART and LPO alterations were observed only in flies with basal bioactivation levels, pointing to direct CTL toxicity to DNA and lipids. Survival, emergence and locomotor behavior were not affected, indicating no bias due to lethality, developmental and behavioral impairment. We suggest that, if related to CTL exposure, DNA and lipid damages may be residual damage of earlier life stages of D. melanogaster. [ABSTRACT FROM AUTHOR]

Species delineation in microorganisms is challenging due to the limited markers available for accurate species assignment. Here, we applied an integrative taxonomy approach, combining extensive sampling, whole-genome sequence-based classification, phenotypic profiling, and assessment of interspecific reproductive isolation. Our work reveals the presence of a distinct Saccharomyces lineage in Nothofagus forests of coastal Patagonia. This lineage, designated Saccharomyces chiloensis sp. nov., exhibits 7% genetic divergence from its sister species S. uvarum, as revealed by whole-genome sequencing and population analyses. The South America-C (SA-C) coastal Patagonia population forms a unique clade closely related to a previously described divergent S. uvarum population from Oceania (AUS, found in Australia and New Zealand). Our species reclassification is supported by a low Ortho Average Nucleotide Identity (OANI) of 93% in SA-C and AUS relative to S. uvarum, which falls below the suggested species delineation threshold of 95%, indicating an independent evolutionary lineage. Hybrid spore viability assessment provided compelling evidence that SA-C and AUS are reproductively isolated from S. uvarum. In addition, we found unique structural variants between S. chiloensis sp. nov. lineages, including large-scale chromosomal translocations and inversions, together with a distinct phenotypic profile, emphasizing their intraspecies genetic distinctiveness. We suggest that S. chiloensis sp. nov diverged from S. uvarum in allopatry due to glaciation, followed by post-glacial dispersal, resulting in distinct lineages on opposite sides of the Pacific Ocean. The discovery of S. chiloensis sp. nov. illustrates the uniqueness of Patagonia's coastal biodiversity and underscores the importance of adopting an integrative taxonomic approach in species delineation to unveil cryptic microbial species. The holotype of S. chiloensis sp. nov. is CBS 18620T. Author summary: Author summary Species delineation in microorganisms is challenging due to limited genetic markers and the genetic complexity of reproductive isolation. In this study, we employed an integrative taxonomy approach, combining whole-genome sequencing, phenotypic profiling, and reproductive isolation assessments, to identify Saccharomyces chiloensis sp. nov., as a new yeast species isolated from the Nothofagus forests of Coastal Patagonia. This novel species exhibits significant genetic divergence from S. uvarum and shows unique structural variants that emphasize its distinct evolutionary lineage. Furthermore, isolates belonging to this species can also be found in Australia and New Zealand, which are genetically and phenotypically different from those isolated in Patagonia. The discovery of S. chiloensis sp. nov. highlights Patagonia's biodiversity's importance and the necessity of comprehensive taxonomic approaches to reveal cryptic species in microorganisms. Our findings have broader implications for understanding yeast diversity and the evolutionary processes shaping microbial species. [ABSTRACT FROM AUTHOR]