The spore-forming anaerobe Clostridioides difficile colonizes the highly dynamic gut environment early after birth, frequently without causing disease. In this study, we aimed to determine how environmental conditions indicative of the infant gut impacted prevalence and physiology of C. difficile. We examined the effect of pH, fermentation derived short-chain carboxylic acids (SCCA) and buffering systems combining in vitro and in vivo analysis, and experimental and modelling approaches. In vivo, the prevalence of Clostridioides significantly increased between 3months (30.2%) and 12months (56.2%) after birth. At 12months, the occurrence of Clostridioides was the highest in feces with near neutral pH (6.7 (IQR 6.5‒7.3). In vitro, C. difficile showed pH-dependent growth and metabolic activity with an optimum around pH 5.8-6.3. Most SCCA conferred antimicrobial activity at pH 5.2 and 6.1 while at pH 6.5, high concentrations of SCCA promoted growth. The presence of phosphate buffer enhanced antimicrobial activity of SCCA, particularly at lower pH values (5.2-5.8). Two multilinear regression models indicated that ionic strength was inversely related to optical density in vitro, while in vivo, the abundance of Clostridioides was inversely linked to the presence of undissociated SCCA. Together, this study highlights that the that occurrence and performance of the opportunistic pathogen C. difficile was affected by chemical systems such as pH, the presence of buffer systems and concentration and chemical state of SCCA. Our results suggest novel targets that could be modulated to impact C. difficile colonization.

Alternaria spp. is one of the fungal genera affecting olive cultivation, and its temporal dynamics are influenced by climatic variations occurring throughout the crop’s vegetative cycle. The aim of this study was to determine the presence of Alternaria spp. in an olive-growing area in northwestern Spain and to examine the relationship between its airborne concentrations and meteorological variables, in order to preliminarily predict its presence in the atmosphere during the olive tree’s phenological cycle. To achieve this, a phenological, aeromycological, and meteorological study was conducted from 2021 to 2024. Alternaria spp. conidia were detected in the air throughout all major phenological stages, with peak concentrations occurring mainly during fruit development. The highest percentages of spores were recorded between 11:00 and 22:00, primarily influenced by temperature and sunlight. During the maturity of fruit stages in 2023 and 2024, isolates from the Alternaria section Alternaria were identified as the cause of olive rot. A predictive model was obtained that estimates the atmospheric concentrations of this type of fungus in the study area, based on average temperature values and hours of sunshine. This study constitutes the first report of Alternaria spp. in an olive-growing area of northwestern Spain and provides models that preliminarily predict its presence. These models can inform growers of the pathogen’s presence in the air before visible symptoms appear, thereby reducing the likelihood of infection in susceptible plants when environmental conditions favor its development.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00248-026-02700-x.

Microbial inoculation is a commonly applied approach in composting to enhance organic matter biodegradation and reduce odor emissions. However, the different characteristics of bacteria in terms of temperature can be considered to optimize their effect during different phases of composting. A mesophilic bacterium, namely Aquamicrobium lusatiense NLF 2-7, was evaluated to mitigate odor emissions and enhance the bacterial community under mesophilic composting. Two different treatments were designed: treatment 1 with a single inoculation on the initial day and treatment 2 with split inoculation at the initial and after 2weeks. Results show that the treatments improve organic matter decomposition by 17.7-28.6% and significantly reduce volatile sulfur compound emissions, especially dimethyl sulfide (DMS) and hydrogen sulfide (H2S) during the initial phase of composting. DMS emissions were mostly emitted in the first week, with reduction rates of 60.3% and 61.5% in both treatments, respectively. Additionally, mean phenol emissions were reduced by 7.9% in treatment 1 and 11.7% in treatment 2. The dominant bacterial phyla during composting were Bacillota, Pseudomonadota, Bacteroidota, and Actinomycetota, comprising 74 to 95% of the total population. This experiment suggests that A. lusatiense NLF 2-7, which is known for reducing sulfur emissions, can also enhance organic matter decomposition. Split inoculation appears more beneficial, with an initial inoculation managing sulfur emissions early on, followed by a second inoculation after the thermophilic phase to control phenol emissions throughout the composting process.

Heat stress poses a significant global challenge to sustainable livestock production, leading to detrimental impacts on animal production and welfare. Reduced appetite and increased body temperature further disrupt the gastrointestinal microbial ecosystem of heat-stressed animals, altering nutrient digestion and affecting host production. However, reported heat-stress-associated microbes have varied across studies, partly due to inconsistencies in microbiota analysis pipelines and taxonomic levels reported. In this study, to identify consistent rumen microbial taxa influenced by heat stress and evaluate potential of rumen microbiota in heat stress prediction, we collected publicly available raw 16S rRNA gene amplicon sequencing data of rumen fluid samples from lactating Holstein cattle housed in thermoneutral or heat stress condition from eight studies, analyzed their microbial composition using a consistent bioinformatic pipeline, and built machine learning models with the rumen microbiota profile to predict heat stress. Important rumen microbial taxa were selected using Boruta (a feature selection algorithm to identify important features) as potential biomarkers to predict heat stress, such as lactate-producing bacteria Lactobacillales, fiber-degrading bacteria Ruminococcaceae UCG-001, and methanogenic archaea Methanomicrobium. Additionally, the random forest model using the available animal factors and relative abundance of rumen microbial taxa showed a much higher performance for heat stress prediction, compared to the model without rumen microbiota profile (Area Under the Curve: 0.851 vs. 0.440). This study confirmed a distinct rumen microbiota signature in heat-stressed lactating Holstein cattle and identified specific rumen microbial taxa as potential biomarkers that could be targeted to mitigate heat-stress responses in dairy cows.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00248-025-02656-4.

Growing evidence suggests that the gut microbiota is closely intertwined with life-history evolution in a wide range of species, including well-studied model organisms like Drosophila melanogaster. Although recent studies have explored the relationship between gut microbiota and female life-history, the link between gut microbiota and male life-history remains relatively unexplored. In this study, we investigated how gut microbiota changes with male age as well as the associations between gut microbiota composition and male life-history traits in D. melanogaster. Using 22 isolines from the Drosophila melanogaster Genetic Reference Panel (DGRP), we measured lifespan, early/late-life reproduction, and early/late-life physiological performance. We characterized the gut microbiota composition in young (5 days old) and old (26 days old) flies using 16S rDNA sequencing. We observed substantial variation in both male life-history traits and gut microbiota composition across isolines and age groups. Using machine learning, we show that gut microbiota composition could predict the chronological age of the organisms with high accuracy. The most important species contributing to machine learning prediction belonged to the Acetobacter and Ralstonia genera. Associations between gut microbiota and life-history traits were also notable, particularly involving different species from the Acetobacter genus. Our findings suggest that taxa such as Acetobacter may be relevant to the evolutionary ecology of host–microbe interactions in male fruit flies.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00248-025-02640-y.

Marine heatwaves affect the abundance and community structure of microbial plankton, with implications for food web and ecosystem processes, but their impact on microbially mediated elemental cycling remains poorly constrained. To determine the biogeochemical effects of increased temperature, we conducted an experiment in September 2023 in which a plankton community from a coastal, productive ecosystem (Ría de Vigo, NW Iberia) was exposed to a warming of + 2°C and + 4°C under unamended and nutrient-enriched conditions. The response of microbial plankton was characterized in terms of organic matter production, carbon fixation, nitrogen uptake, and oxygen net production. We found that warming caused increased nutrient consumption and biomass production, as well as faster bloom dynamics, both in unamended and nutrient-enriched treatments, indicating that the community was robust to thermal perturbation. Accelerated nutrient depletion under warming gave way to an earlier decrease in carbon fixation and nitrate uptake rates, together with a shift towards a negative or less positive metabolic balance. Carbon fixation was less sensitive than nitrate uptake to the different temperature and nutrient scenarios, leading to wide changes in the carbon-to-nitrogen uptake ratio, while respiration increased non-linearly with temperature. Overall, the investigated microbial fluxes were more responsive to nutrient availability than to temperature. Our results show that microbially driven ecosystem services in coastal waters have the potential to be enhanced during short-term warming events.

Eukaryotic microorganisms are an important, but understudied, component of freshwater aquatic ecosystems, and are significant sources of mortality in early life stages of fishes in natural and aquaculture systems. The eukaryotic microbiome colonizing egg surfaces of the lake sturgeon (Acipenser fulvescens) was characterized from eggs collected in natural stream habitats and a streamside hatchery in the Cheboygan River watershed in MI, USA. The taxonomic diversity of members of the Kingdoms Fungi and Stramenopile associated with infections of lake sturgeon eggs during spawning is contributing to lake sturgeon mortality in the hatchery. Characterization of the microbial communities from deposited eggs demonstrated heavy influence of spawning location on the diversity of Pythium, an Oomycete predominating in the microbiome. The Ascomycota also had a strong and distinguishing presence, with members of the Dothidiales found only on eggs from the streamside hatchery. Aureobasidium pullulans, a ubiquitous pigmented yeast, was present in the greatest numbers of egg samples, and Helotiales were found only on samples from the Black River. Independent isolates were collected from egg surfaces and tested for chemical sensitivity to the oomicides ethaboxam and mefenoxam, which are used for control of Oomycete agricultural pathogens. Ethaboxam inhibited mycelial growth almost completely for all Saprolegnia strains tested, while mefenoxam, at 20 × strength, was largely ineffective. Water prevents the natural inactivation of mefenoxam by light, thus is not advisable in aquatic systems, where it could accumulate. Alternatively, ethaboxam may be a nonpersistent, welcome control option for these fish pathogens.

Glyphosate-based herbicides are among the most widely used agricultural chemicals globally, and their widespread application presents risks to environmental health and aquatic ecosystems. Continuous glyphosate inputs disrupt phytoplankton communities, potentially triggering harmful algal blooms. This study examines the proliferation of microalgal species exposed to low glyphosate concentrations (0.05 mg/L) and various phosphorus sources, with a particular focus on C-P and C-O-P bond phosphonates, which have been insufficiently studied in previous research. We hypothesized that cyanobacteria might exhibit a competitive growth advantage over other algal species when exposed to C-P bond glyphosate, especially under phosphorus-limited conditions. In monoculture experiments, Microcystis aeruginosa and Peridinium umbonatum var. inaequale significantly increased their biomass when cultured with C-P bond phosphonates, whereas Scenedesmus bijuga failed to thrive under similar conditions. Peridinium umbonatum var. inaequale also displayed increased soluble protein content in response to glyphosate stress, indicating an adaptive stress response. In co-culture experiments, M. aeruginosa demonstrated greater tolerance to glyphosate than P. umbonatum var. inaequale, though biomass increases were not significantly correlated with soluble protein or APA. Sediment-water interface experiments revealed that glyphosate exposure significantly promoted cyanobacterial biomass, which was approximately five times greater than that of the inorganic phosphorus group. Notably, when cyanobacterial biomass exceeded 20% of the total, Cyanophyta replaced Chlorophyta as the dominant group, suggesting a potential competitive advantage under low-dose glyphosate exposure. These findings highlight that glyphosate may promote cyanobacterial dominance by altering phytoplankton community composition, potentially contributing to the increased frequency of harmful algal blooms in nutrient-limited aquatic environments.

Shifts in agricultural land use over the past 200 years have led to a loss of nearly 50% of existing wetlands in the USA, and agricultural activities contribute up to 65% of the nutrients that reach the Mississippi River Basin, directly contributing to biological disasters such as the hypoxic Gulf of Mexico “Dead” Zone. Federal efforts to construct and restore wetland habitats have been employed to mitigate the detrimental effects of eutrophication, with an emphasis on the restoration of ecosystem services such as nutrient cycling and retention. Soil microbial assemblages drive biogeochemical cycles and offer a unique and sensitive framework for the accurate evaluation, restoration, and management of ecosystem services. The purpose of this study was to elucidate patterns of soil bacteria within and among wetlands by developing diversity profiles from high-throughput sequencing data, link functional gene copy number of nitrogen cycling genes to measured nutrient flux rates collected from flow-through incubation cores, and predict nutrient flux using microbial assemblage composition. Soil microbial assemblages showed fine-scale turnover in soil cores collected across the topsoil horizon (0–5 cm; top vs bottom partitions) and were structured by restoration practices on the easements (tree planting, shallow water, remnant forest). Connections between soil assemblage composition, functional gene copy number, and nutrient flux rates show the potential for soil bacterial assemblages to be used as bioindicators for nutrient cycling on the landscape. In addition, the predictive accuracy of flux rates was improved when implementing deep learning models that paired connected samples across time.

Classical aerobiological studies commonly use high-volume air samplers to quantify and identify cultivable airborne bacteria and fungi. However, this approach introduces a significant bias, as it overlooks the non-cultivable fraction, which likely constitutes a major component of the airborne microbiome. The advent of next-generation sequencing (NGS) has addressed this limitation, enabling a more comprehensive characterization of the cave aerobiome. This study analyzes both cultivable and non-cultivable airborne bacteria from Covadura and C3 caves, located in the Gypsum Karst of Sorbas (SE Spain). A total of 24 bacterial genera were identified using culture-based methods, whereas NGS revealed 749 genera. Culture-based methods using the surface air system (SAS) predominantly recovered Gram-positive spore-forming bacteria from the phyla Bacillota and Actinomycetota, which were largely absent or present in low relative abundances in the NGS datasets. In contrast, NGS revealed a broader diversity, including numerous Gram-negative and rare airborne bacteria not detected by culture. The NGS results from airborne samples showed greater similarity to the microbial communities found in cave biofilms and sediments, suggesting that a portion of airborne bacteria originates from within the cave and is influenced by microclimatic conditions such as ventilation and air stagnation. Although the short-read sequencing approach used in this study has limitations, such as reduced taxonomic resolution compared to the culture-based approach, it remains the most effective tool for capturing the diversity and ecological patterns of airborne microorganisms. The integration of gas tracers and other environmental data allowed the identification of zones within the cave with different ventilation patterns and degrees of isolation, which corresponded to different spatial distributions of airborne bacteria. Our findings underscore that reliable aerobiological studies in caves require the combination of non-culture dependent-based sequencing approaches and environmental monitoring to fully understand the origin, diversity, and ecological dynamics of airborne microbial communities.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00248-025-02591-4.