Understanding air microbial content, especially in highly polluted urban areas, is crucial for assessing its effect on human health and ecosystems. In this context, the impact of gaseous pollutants on the aerobiome remains inconclusive due to a lack of studies separating this factor from other contaminants or environmental factors. In this study, we aimed to experimentally assess the influence of contrasting concentrations of atmospheric gaseous pollutants as isolated variables on the composition of the aerobiome. Our study sites were contrasting Air Quality Index (AQI) sites of the Metropolitan Region of Chile, where nitric oxide (NO) was significantly lower at the low-AQI site than at the high-AQI site, while ozone (O₃) was significantly higher. Cultivable aerobiome communities from the low-AQI site were exposed to their own pollutants or those from the high-AQI site and characterized using high-throughput sequencing (HTS), which allowed comparisons between the entire cultivable communities. The results showed increased alpha diversity in bacterial and fungal communities exposed to the high-AQI site compared to the low-AQI site. Beta diversity and compositional hierarchical clustering analyses revealed a clear separation based on NO and O₃ concentrations. At the phylum level, four bacterial and three fungal phyla were identified, revealing an over-representation of Actinobacteriota and Basidiomycota in the samples transferred to the high-AQI site, while Proteobacteria were more abundant in the community maintained at the low-AQI site. At the functional level, bacterial imputed functions were over-represented only in samples maintained at the low-AQI site, while fungal functions were affected in both conditions. Overall, our results highlight the impact of NO and/or O₃ on both taxonomic and functional compositions of the cultivable aerobiome. This study provides, for the first time, insights into the influence of contrasting pollutant gases on entire bacterial and fungal cultivable communities through a controlled environmental intervention.

Living in arid environments presents unique challenges to organisms, including limited food and water, extreme temperatures, and UV exposure. Reptiles, such as the South American leaf-toed gecko (Phyllodactylus gerrhopygus), have evolved remarkable adaptations to thrive in such harsh conditions. The gut microbiome plays a critical role in host adaptation and health, yet its composition remains poorly characterized in desert reptiles. This study aimed to characterize the composition and abundance of the gut microbiome in P. gerrhopygus inhabiting the hyperarid Atacama Desert, taking into account potential sex differences. Fecal samples from adult female and male geckos were analyzed by 16S rRNA gene amplicon sequencing. No significant differences in bacterial alpha diversity were observed between the sexes. However, the phylum Bacteroidota was more abundant in females, while males had a higher Firmicutes/Bacteroidota ratio. The core microbiome was dominated by the phyla Bacteroidota, Firmicutes, and Proteobacteria in both sexes. Analysis of bacterial composition revealed 481 amplicon sequence variants (ASVs) shared by female and male geckos. In addition, 108 unique ASVs were exclusive to females, while 244 ASVs were unique to males. Although the overall bacterial composition did not differ significantly between the sexes, certain taxa exhibited higher relative abundances in each sex group. This study provides insight into the taxonomic structure of the gut microbiome in a desert-adapted reptile and highlights potential sex-specific differences. Understanding these microbial communities is critical for elucidating the mechanisms underlying host resilience in Earth’s most arid environments, and for informing conservation efforts in the face of ongoing climate change.

Marine fog is a key non-rainfall water source that sustains microbial activity and transports dissolved nutrients inland, influencing early soil development in hyperarid ecosystems. However, the mechanisms through which sustained fog inputs drive soil surface modification and biocrust formation remain poorly understood. This study evaluated the effects of long-term fog augmentation on soil surface development, biocrust dynamics, and associated microbial communities in the Atacama Desert. We implemented a four-year fog addition field experiment with three sampling times (T0, T24, T48) to assess changes in soil physicochemical properties, biocrust composition, and the integrated multi-diversity of archaea, bacteria, fungi and protist. Sustained fog input transformed bare soils into biological soil crusts, particularly lichen- and moss-dominated stages. This transition was accompanied by increases in soil nitrogen, variations in organic matter accumulation, a shift from alkaline to near-neutral pH, and improvements in soil stability and water retention. Multi-diversity increased over time and was positively associated with ecosystem variables linked to water availability, structural stabilization, and decomposition. These functions, integrated into an ecosystem multifunctionality index, also increased under prolonged fog input, revealing a positive relationship between multifunctionality and multi-diversity. Overall, the results demonstrate that sustained fog input strongly enhances early soil surface development and biocrust establishment, highlighting the ecological importance of marine fog in shaping biodiversity and ecosystem functioning in hyperarid landscapes.

The gut microbiome plays a fundamental role in host ecophysiology. Numerous studies have examined microbiome composition and functionality to understand the ecological and evolutionary factors shaping host–microbe interactions. However, the consequences of these patterns for animal ecology remain poorly understood. Here, we examined how variations in the gut microbiome influence fitness differences among Drosophila species sharing a common dietary niche. Using 16S rRNA gene sequencing, we analyzed the gut microbial taxonomy and predicted functional profiles of 4 Drosophila species collected in central Chile. Our results revealed a strong signal of phylosymbiosis in the microbial taxonomy, while functionality was highly redundant across the studied fly species. Functional biomarkers analysis indicated that the gut microbiome supports the nutritional requirements of D. simulans (Sturtevant), D. hydei (Sturtevant), and D. repleta (Wollaston); whereas, this was less evident in D. melanogaster (Meigen). To assess the potential contribution of the microbiome to host performance, we compared egg-to-adult viability between 2 species with the greatest physiological divergence: D. simulans and D. hydei. Notably, D. simulans exhibited significantly higher egg viability and shorter development time than D. hydei. Strikingly, the D. simulans microbiome contained more taxonomic and functional biomarkers previously demonstrated to enhance fly fitness, whereas the D. hydei microbiome harbored taxa and functions potentially detrimental to host performance. These findings suggest that the gut microbiome contributes to host fitness and may shape the evolutionary ecology of Drosophila species, with broader implications for community dynamics, including interspecific competition and species displacement.