Biology subjects

Oren, A.

Publications and source records attributed to Oren, A..

3 recordsLinked to original sources

bioRxiv2025

Metagenomics reveal allopatric speciation and higher connectivity among coastal vs. inland hypersaline lakes and solar salterns

Hypersaline environments, due to their discrete and geographically isolated nature, constitute ideal systems for studying evolutionary patterns and microbial diversification, and especially here when contrasting coastal with inland systems. Based on metagenomic comparisons of 25 hypersaline sites across 11 countries, we explored the influence of environmental factors, ionic composition, and geographic distance on their microbial community structures and taxa diversification. Our results revealed that microbial communities from coastal environments were taxonomically and functionally more similar to each other than to those from inland sites. A distance-decay relationship in the genetic relatedness, significantly more pronounced for the coastal sites, was observed among reconstructed metagenome-assembled genomes (MAGs), clearer at distances below 400 km, but still detectable across global scales up to 20,000 km. The 484 MAGs recovered, representing 284 distinct species, revealed a striking global ubiquity, with 62.5% of the species showed cosmopolitanism as were detected across multiple sites. The higher taxonomic and genetic similarity of coastal environments over the inland sites seems to reflect an environmental connection that may be related to the ocean current dynamics. Most cosmopolitan species showed clear allopatric differentiation, although few cases of a single globally dominant genomovar (average nucleotide identity, ANI > 99.8%) were also observed, especially for some Haloquadratum species. The findings suggest that coastal hypersaline systems are loosely constrained by geographic isolation, with clear signals of allopatric speciation at the mesoscale (tenths to hundreds of kilometers) that become blurrier at larger scales.

microbiology↗

bioRxiv2021

Metagenomic investigation of the equine faecal microbiome reveals extensive taxonomic and functional diversity

BackgroundThe horse plays crucial roles across the globe, including in horseracing, as a working and companion animal and as a food animal. The horse hindgut microbiome makes a key contribution in turning a high fiber diet into body mass and horsepower. However, despite its importance, the horse hindgut microbiome remains largely undefined. Here, we applied culture-independent shotgun metagenomics to thoroughbred equine faecal samples to deliver novel insights into this complex microbial community. ResultsWe performed metagenomic sequencing on five equine faecal samples to construct 123 high- or medium-quality metagenome-assembled genomes from Bacteria and Archaea. In addition, we recovered nearly 200 bacteriophage genomes. We document surprising taxonomic and functional diversity, encompassing dozens of novel or unnamed bacterial genera and species, to which we have assigned new Candidatus names. Many of these genera are conserved across a range of mammalian gut microbiomes. ConclusionsOur metagenomic analyses provide new insights into the bacterial, archaeal and bacteriophage components of the horse gut microbiome. The resulting datasets provide a key resource for future high-resolution taxonomic and functional studies on the equine gut microbiome.

genomics↗

bioRxiv2019

Trophic Selective Pressures Organize the Composition of Endolithic Microbial Communities from Global Deserts

Studies of microbial biogeography are often convoluted by extremely high diversity and differences in microenvironmental factors such as pH and nutrient availability. Desert endolithic (inside rock) communities are exceptionally simple ecosystems that can serve as a tractable model for investigating long-range biogeographic effects on microbial communities. We conducted a comprehensive survey of endolithic sandstones using high-throughput marker gene sequencing to characterize global patterns of diversity in endolithic microbial communities. We also tested a range of abiotic variables in order to investigate the factors that drive community assembly at various trophic levels. Macroclimate was found to be the primary driver of endolithic community composition, with the most striking difference witnessed between hot and polar deserts. This difference was largely attributable to the specialization of prokaryotic and eukaryotic primary producers to different climate conditions. On a regional scale, microclimate and properties of the rock substrate were found to influence community assembly, although to a lesser degree than global hot versus polar conditions. We found new evidence that the factors driving endolithic community assembly differ between trophic levels. While phototrophic taxa were rigorously selected for among different sites, heterotrophic taxa were more cosmopolitan, suggesting that stochasticity plays a larger role in heterotroph assembly. This study is the first to uncover the global drivers of desert endolithic diversity using high-throughput sequencing. We demonstrate that phototrophs and heterotrophs in the endolithic community assemble under different stochastic and deterministic influences, emphasizing the need for studies of microorganisms in context of their functional niche in the community.

microbiology↗