Plants inhabiting arid and semi-arid ecosystems rely on their associated microbiota to withstand drought, heat, salinity, and nutrient limitation. We investigated the bacterial communities associated with the foliar tissues, roots, and rhizospheric soil of the desert plant Citrullus colocynthis (L.) Schrad. growing in semi-arid Morocco using 16S rRNA gene amplicon sequencing, culture-dependent isolation, and genome-informed functional profiling of selected tissue-associated isolates. Bacterial communities exhibited strong compartmentalization, with the rhizospheric soil harboring the highest diversity, followed by roots and foliar tissues. Across compartments, communities were dominated by Pseudomonadota, Actinomycetota, Bacillota, and Bacteroidota, while several bacterial families showed compartment-specific enrichment consistent with roles in plant colonization, nutrient cycling, and stress adaptation. Soil physicochemical properties were significantly associated with community composition but explained only part of the observed variation, indicating an additional role for host-mediated selection in microbiome assembly. Cultivation recovered diverse bacteria from root and foliar tissues, mainly belonging to Achromobacter, Pseudomonas, and Glutamicibacter, most of which were also detected by amplicon sequencing. Genomic analyses identified traits associated with stress tolerance, osmoprotection, nutrient acquisition, colonization, and plant growth promotion. These findings reveal a structured and functionally diverse bacteriome in C. colocynthis and highlight this desert-adapted plant as a promising source of beneficial microorganisms for future experimental evaluation under water-limited conditions.
The mammalian gut microbiome represents a critical symbiotic ecosystem influencing host metabolism, immunity, and ecological adaptation, yet comprehensive understanding of how ecological and environmental factors shape microbial diversity across mammalian species remains limited, constraining our ability to predict microbiome responses to global environmental change and inform conservation strategies. This study addresses this knowledge gap through an integrative meta-analysis of 1,443 high-quality gut microbiome samples from 173 wild mammalian species spanning diverse global habitats, integrating high-resolution climate data (temperature and precipitation), ecological variables (diet type, habitat range, and body mass), IUCN conservation status, and advanced metagenomic analyses using QIIME 2 with phylogenetic diversity metrics and multivariate statistical models. Diet type emerged as the dominant ecological determinant, with herbivores harbouring significantly higher microbial diversity than carnivores (Faith PD approximately 2.1-fold higher; 95
The gut microbiota is increasingly recognized as a key determinant of host health, but its compositional dynamics in diseased medicinal leeches (Hirudinaria manillensis) remain unexplored. Using 16S rRNA amplicon sequencing, we profiled gut microbial communities in healthy leeches and those with characteristic disease symptoms. Across 528 amplicon sequence variants (ASVs), 232 were unique to healthy and 173 to diseased individuals. Alpha diversity showed no significant differences between groups, and beta diversity revealed no overall separation (ANOSIM, R = -0.0019, p = 0.442), though healthy individuals clustered more tightly. A Gut Microbiome Health Index (GMHI), based on health- and disease-associated bacterial signatures, was significantly higher in healthy leeches and outperformed Shannon diversity in discriminatory power. Prevalence-based classification showed persistent taxa comprised 57.9
Inland hypersaline lagoons are distinctive microbial habitats, yet their fungal diversity remains poorly characterized, particularly in Europe. We compared sediment fungal and prokaryotic communities from Salada Grande de Chiprana, the only permanent deep hypersaline lagoon in Western Europe, and the nearby oligohaline lagoon La Estanca using ITS1 and ITS2 metabarcoding for fungi and 16S rRNA gene amplicon sequencing for prokaryotes. Fungal communities were dominated by Ascomycota, Rozellomycota and Basidiomycota, when the ITS1 and ITS2 datasets were considered jointly, whereas prokaryotic assemblages were mainly composed of Pseudomonadota, Cyanobacteriota, Bacteroidota, and Chloroflexota. Alpha diversity did not differ significantly between lagoons for fungal communities, although ITS2 recovered a significantly higher number of observed ASVs than ITS1 (p = 0.016). Bray–Curtis-based PERMANOVA indicated that fungal community composition was significantly associated with lagoon identity and molecular marker, with marker choice explaining more variation than lagoon identity and a significant lagoon × marker interaction. Conductivity, used as a proxy for salinity, explained a limited and non-significant fraction of fungal community variation; however, its independent contribution could not be separated from other environmental differences between the two lagoons. In contrast, prokaryotic communities showed taxonomic differences between lagoons but no statistically significant beta-diversity separation, with substantial within-lagoon variability. A large fraction of fungal ASVs remained taxonomically or functionally unclassified, suggesting that these sediments harbor poorly characterized fungal diversity. Overall, our results indicate that fungal and prokaryotic communities respond differently across contrasting lagoon environments and show that ITS1 and ITS2 recover complementary views of fungal diversity, underscoring the need to consider marker choice when interpreting metabarcoding-based ecological patterns.
Exchange of genetic information within extreme environments is mediated by mobile genetic elements, most notably plasmids, which play a crucial role in microbial adaptation and survival in harsh environmental conditions. In this study, we characterized a novel plasmid pHv20-59a (194 kb) identified in Halovibrio sp. isolated from a hypersaline brine in Solivar near Prešov (Slovakia). Although the absence of canonical relaxase suggests that autonomous conjugative transfer is unlikely, bioinformatic approaches revealed that the plasmid possesses highly conserved regions shared with other members of the Halomonadaceae family. Plasmid annotation revealed a functional potential that may contribute to a selective advantage under stress conditions, particularly through a broad repertoire of heavy metal tolerance genes (mer and cop operons) and increased heavy metal tolerance correlating with the identified heavy metal content. Since initial experiments to remove the plasmid from the cells were unsuccessful and other curing strategies still require testing, these findings suggest that the putative toxin-antitoxin systems may contribute to the maintenance of this replicon in the host cell, highlighting its potential biological significance in halophilic bacteria. Our finding of a conserved plasmid backbone shared across phylogenetically distinct halophilic hosts provides evidence for its dissemination by horizontal gene transfer in hypersaline environments. This work represents the first characterization of a plasmid from the genus Halovibrio and expands current knowledge of plasmid diversity and evolution in extreme environments.
