Hospital environments host diverse microbial communities that may contribute to nosocomial infections. Moisture-retaining surfaces such as cleaning sponges and faucet edges represent high-contact, under-investigated hygiene hotspots, particularly in wards caring for immunocompromised patients. Environmental samples were collected from cleaning sponges (n = 14) and faucet edges (n = 4) across multiple hospital rooms of a paediatric haematology–oncology unit, with domestic physician sponges as controls (n = 3). DNA was extracted and sequenced targeting the V3–V4 and V7–V9 hypervariable regions of the 16S rRNA gene on the Illumina MiSeq platform. Taxonomic composition and alpha/beta diversity were assessed using QIIME 2 and R. Sponge samples were dominated by Moraxellaceae, particularly Acinetobacter and Enhydrobacter, and showed significantly lower alpha diversity than faucet samples (Shannon index: Kruskal–Wallis H = 8.4, p = 0.01; Faith’s phylogenetic diversity: H = 9.17, p = 0.01). Faucet samples were enriched in human-associated genera including Staphylococcus, Streptococcus, and Chryseobacterium. Statistically significant beta-diversity differences were detected between sponge and faucet communities by PERMANOVA based on Bray–Curtis dissimilarity (p = 0.01), whereas no significant clustering by room or floor location was observed (p = 0.29). Potentially pathogenic taxa including Aeromonas, Pseudomonas, and Enterobacteriaceae were identified across both surface types. Domestic control sponges showed distinct microbiome profiles from hospital samples. Microbial communities differ significantly between hospital sponges and faucets, with surface type rather than location as the primary determinant of community structure. The presence of opportunistic pathogens on both surface types highlights the importance of enhanced hygiene protocols, inclusion of faucet edges and sink drains in routine decontamination schedules, and regular microbiological surveillance in clinical settings caring for immunocompromised patients.

The study explores the vertical stratification of microbial diversity and metabolic potential in Earth’s lower atmosphere. Using 16S rRNA sequencing data spanning the planetary boundary layer to the lower stratosphere, we conducted taxonomic profiling and metabolic pathways predictions. The aim was to elucidate microbial community dynamics and their ecological roles under diverse atmospheric conditions. Methods: 51 Publicly available datasets with 3584 samples were retrieved from repositories such as Sequencing Read Archive and European Nucleotide Archive, filtered for studies employing 16S rRNA sequencing. Quality control was performed using FastQC and Trimmomatic, followed by taxonomic classification with Qiime2 and the Silva132 database. Functional pathway predictions were derived using PICRUSt2, and statistical analyses included Kruskal-Wallis tests for diversity comparisons and Mann-Whitney U tests for pathway activity. Results: Microbial diversity decreased with altitude, with the Surface Layer exhibiting the highest Shannon diversity and the significantly decreased in Low Stratosphere. Taxonomic composition shifted along the elevation gradient, with Actinobacteria and Alphaproteobacteria predominant at lower altitudes. In contrast, Bacilli and Gammaproteobacteria became more dominant at higher elevations, though they maintained a notable presence at lower sites as well. Functional analysis revealed altitude-specific adaptations, including significant upregulation of CO₂ fixation pathways in the Free Troposphere Transition Layer and secondary metabolite biosynthesis in the lower stratosphere. Discussion: These findings reveal distinct microbial metabolic profiles across atmospheric layers with varying conditions such as oxygen levels, UV radiation, and nutrient availability. While these differences may represent adaptive strategies, they could also reflect source environment characteristics or selective transport processes. The conserved metabolic pathways across altitude layers suggest functional resilience despite taxonomic divergence. These results have implications for astrobiology, providing analogs for microbial life in extraterrestrial environments like Mars or Europa. In summary, this study advances our understanding of aerobiomes’ ecological roles and their potential as models for life detection in extreme environments, bridging atmospheric microbiology with astrobiological exploration.