Biology subjects

Reinthaler, T.

Publications and source records attributed to Reinthaler, T..

3 recordsLinked to original sources

bioRxiv2026

Marine bacterial resistomes integrate ecological adaptation with anthropogenic amplification: genome-resolved insight along a gradient of human impact

Antibiotic resistance genes (ARGs) are ubiquitous in marine environments, yet whether their distribution primarily reflects anthropogenic pollution or intrinsic ecological functions remains unresolved. We used genome-resolved metagenomics to characterize resistomes in 371 genomic operational taxonomic units (gOTUs) across a gradient of human impact: the heavily impacted Baltic Sea, the moderately impacted North Sea, and the minimally impacted West Greenland shelf. ARG density was distinctly elevated in the Baltic Sea (3.20 ARGs Mbp-1) relative to the North Sea (1.90) and West Greenland (1.67), which did not differ significantly from each other, suggesting a relatively uniform oceanic baseline. Variance partitioning revealed that taxonomic identity explained 20.1% of ARG density variation, with environment contributing 11.4%; critically, Baltic gOTUs carried 35.1% more ARGs than predicted from taxonomy alone, indicating environment-driven enrichment beyond baseline taxonomic carriage. Lifestyle-dependent ARG partitioning between particle-attached and free-living prokaryotes emerged only under anthropogenic pressure: free-living bacteria were enriched in multiple resistance classes in the Baltic Sea but showed no differentiation in West Greenland. Only 0.85% of detected ARGs showed [≥]70% amino acid identity to clinically characterized sequences in the CARD database, showing that marine ARGs are highly divergent from clinical resistance determinants. Virulence factor annotations were widespread but weakly coupled with ARG abundance, suggesting independent ecological selection. Our results suggest that marine resistomes integrate an intrinsic baseline of ecological functions with selective enrichment of specific resistance mechanisms under anthropogenic pressure, and that genome-resolved approaches are able to quantify the relative contributions of each.

microbiology↗

bioRxiv2025

Comparison of picolyl azide-based BONCAT and microautoradiography for assessing the heterotrophic prokaryotic activity in the deep ocean

Prokaryotes play a central role in marine biogeochemical cycles, yet quantifying their activity requires sensitive methods due to low biomass and metabolic rates, particularly in the deep ocean. One recent method to determine single-cell activity of prokaryotes is bioorthogonal non-canonical amino acid tagging (BONCAT), which offers a non-radioactive approach to measure protein synthesis. However, direct comparisons between BONCAT and radioisotope-based techniques across ocean depth gradients remain limited, particularly for low-activity prokaryotic communities. To address this knowledge gap, we tested an optimised BONCAT protocol using picolyl azide fluorophores (BONCAT-pic) to assess single-cell heterotrophic activity in prokaryotic communities from surface to bathypelagic depths (1000-4000 m) in the Southern Ocean near the Kerguelen Islands. The method was first optimised using aged coastal and open-ocean seawater, and then compared to microautoradiography with 3H-methionine uptake. Statistical analysis shows that BONCAT-pic significantly improved detection sensitivity compared to standard azide reagents. BONCAT-pic consistently detected active cells in profiles over the open ocean water column, with cell proportions and fluorescence signals closely correlating with both microautoradiography (R2 = 0.9, p < 0.001) and bulk methionine incorporation (R2 = 0.6, p < 0.001). Our results demonstrate that BONCAT-pic is a reliable, fluorescence-based method for quantifying heterotrophic activity at the single-cell level, extending its applicability to prokaryotic communities in the deep ocean.

microbiology↗

bioRxiv2022

Impact of hydrostatic pressure on organic carbon cycling of the deep-sea microbiome

Deep-sea microbial communities are exposed to high hydrostatic pressure. While some of these deep-sea prokaryotes are adapted to high-pressure conditions, the contribution of piezophilic (i.e., pressure-loving) and piezotolerant prokaryotes to the total deep-sea prokaryotic community remains unknown. Here we show that the metabolic activity of prokaryotic communities is increasingly inhibited with increasing hydrostatic pressure. At 4,000 m depth, the bulk heterotrophic prokaryotic activity under in situ hydrostatic pressure was only about one-third of that measured on the same community at atmospheric pressure conditions. Only [~]5% of the bathypelagic prokaryotic community are piezophilic while [~]85% of the deep-sea prokaryotes are piezotolerant. A small fraction ([~]10%) of the deep-sea prokaryotes is piezosensitive (mainly members of Bacteroidetes, Alteromonas) exhibiting specific survival strategies at meso- and bathypelagic depths. These piezosensitive bacteria elevated their activity by more than 100-fold upon depressurization. Hence, the consistently higher bulk metabolic activity of the deep-sea prokaryotic community measured upon depressurization is due to a rather small fraction of the prokaryotic community. Overall, the heterotrophic prokaryotic activity in the deep-sea is substantially lower than hitherto assumed with major impacts on the oceanic carbon cycling.

ecology↗