Biology subjects

Stach, T. L.

Publications and source records attributed to Stach, T. L..

5 recordsLinked to original sources

bioRxiv2026

Automated refinement of metagenomic bins and estimation of binning success using itBins

Most prokaryotic genomes in public databases are genomes reconstructed from metagenomes, forming a compendium of multiple contiguous sequences (contigs) assembled from shotgun sequencing data. Binning algorithms for assigning contigs to metagenome assembled genomes (MAGs) are manifold and continuously improving in accuracy. However, binning errors, i.e. the incorrect assignment of a contig and coding sequence to a MAG, often propagate through various databases and confound taxonomic, metabolic and/or evolutionary analyses. Here we present itBins, a fully automated python-based software that enables ultra-fast refinement of metagenomic bins using a rule-based approach harnessing information from %GC content (%GC for brevity), coverage, and taxonomy of individual contigs. When applied to the low, medium, and high complexity data of the Critical Assessment of Metagenome Interpretation (CAMI I) challenge [1], itBins produced higher F1 scores (the harmonic mean of precision and recall) for all levels compared to other automated refinement tools, i.e., MDMcleaner and Rosella. Compared to manual refinement via uBin, itBins performed similarly well across all three complexity levels of the CAMI I dataset. With an average speed of 61 ms per bin, itBins is faster than all other refinement tools by at least three orders of magnitude when input data is accordingly available (%GC, coverage, and taxonomy), and was similarly fast when input data preparation was included in the processing time. Application to 64 real-world metagenomes from highly complex river mesocosms resulted in 259 medium-quality and 19 high-quality MAGs refined by itBins, while the other automated refinement tools failed in generating output at all or within 5000 hours of runtime. Finally, itBins also utilizes marker genes to determine the overall binning success for individual metagenomes, providing a crucial benchmark for the user to estimate the ecological relevance of their binned data. The herein introduced software itBins is broadly applicable to any type of metagenome data, integrates well with other software like DASTool, and enables swift and reliable refinement of genomes from metagenomes along with estimation of the overall binning success. itBins is distributed via EUPL 1.2 license and available at Codeberg (codeberg.org/JMK/itBins), GitHub (github.com/ProbstLab/itBins) and through Bioconda [2](bioconda.github.io/recipes/itbins/README.html).

bioinformatics↗

bioRxiv2025

A uniform stress response of stream microbiomes in the hyporheic zone across North America

BackgroundStream hyporheic zones represent a unique ecosystem at the interface of stream water and surrounding sediments, characterized by high heterogeneity and accelerated biogeochemical activity. These zones are increasingly impacted by anthropogenic stressors and environmental changes at a global scale, directly altering their microbiomes. Despite their importance, the current body of literature lacks a systematic understanding of active nitrogen and sulfur cycling across stream sediment and surface water microbiomes, particularly across geographic locations and in response to environmental stressors. ResultsBased on previously published and unpublished datasets, 363 stream metagenomes were combined to build a comprehensive MAG and gene database from stream sediments and surface water including a full-factorial mesocosm experiment which had been deployed to unravel microbial stress response. Metatranscriptomic data from 23 hyporheic sediment samples collected across North America revealed that microbial activity in sediments was distinct from the activity in surface water, contrasting similarly encoded metabolic potential across the two compartments. The expressed energy metabolism of the hyporheic zone was characterized by increased cycling of sulfur and nitrogen compounds, governed by Nitrospirota and Desulfobacterota lineages. While core metabolic functions like energy conservation were conserved across sediments, temperature and stream order change resulted in differential expression of stress response genes previously observed in mesocosm studies. ConclusionsThe hyporheic zone is a microbial hotspot in stream ecosystems, surpassing the activity of overlaying riverine surface waters. Metabolic activity in the form of sulfur and nitrogen cycling in hyporheic sediments is governed by multiple taxa interacting through metabolic handoffs. Despite the spatial heterogeneity of streams, the hyporheic sediment microbiome encodes and expresses conserved stress responses to anthropogenic stressors, e.g., temperature, in streams of separate continents. The high number of uncharacterized differentially expressed genes as a response to tested stressors is a call-to-action to deepen the study of stream systems.

microbiology↗

bioRxiv2024

Complex compositional and cellular response of river sediment microbiomes to multiple anthropogenic stressors

Rivers face constant anthropogenic stressors, resulting in significant changes in microbial community composition. What remains unclear is whether these changes render the microbiome better adapted to the stressed environment. Here, by subjecting 64 river-connected mesocosms to multiple stressors, we show that sediment microbiomes of small lowland rivers are highly sensitive to lowered flow velocity resulting in substantially altered community compositions not fully capable of compensating for the stressor effect within two weeks albeit having stable functions encoded in metagenomes. Transcriptomics revealed a systematic heat shock response in the community and a highly active, previously unknown anaerobic key stone species with great metabolic versatility. Increases in temperature (+3.5 {degrees}C) or salinity (+0.5 mS/cm) were outcompeted by lowered flow and elicited only minor responses at community or transcriptomic level with, e.g., upregulation of the photosystem of chloroplasts. Following a two-week recovery period, transcriptomic stress responses vanished completely compared to control mesocosms, exemplifying the river microbiomes resilience. We conclude that, given the complex community responses at both the cellular and compositional level, maintaining natural river flow is vital to preventing energy loss and reduced microbiome activity in river sediments.

ecology↗

bioRxiv2023

Virus-host dynamics in archaeal groundwater biofilms and the associated bacterial community composition

Lytic viruses can be prevalent in deep groundwater, yet their spatial and temporal distribution in such an ecosystem remains unexplored. Here, we tackle this gap of knowledge by studying viral infections in individual, archaea-dominated biofilm flocks sampled from deep anoxic groundwater over a period of three years. Using virusFISH whose detection efficiency for individual viral particles was 15%, we show a significant and steady increase of virus infections between the years 2019 and 2022. Based on various fluorescence micrographs of individual biofilm flocks, we determined different stages of viral infections in biofilms for single sampling events, demonstrating the progression of infection of biofilms in deep groundwater. Biofilms associated with many host cells undergoing lysis showed a substantial accumulation of filamentous microbes around infected cells probably feeding off host cell debris. Using 16S rRNA gene sequencing across ten individual biofilm flocks from one sampling event, we determined that the associated bacterial community remains relatively constant and was dominated by Desulfobacterota. Given the stability of the virus-host interaction in these deep groundwater samples, we postulate that the virus-host dynamics of Ca. Altiarchaeum hamiconexum and its abundant virus Altivir_l_MSI described herein represent a suitable model system for studying deep biosphere virus-host interactions in future research endeavors.

microbiology↗

bioRxiv2020

uBin - a manual refining tool for metagenomic bins designed for educational purposes

Resolving bacterial and archaeal genomes from metagenomes has revolutionized our understanding of Earths biomes, yet producing high quality genomes from assembled fragments has been an ever-standing problem. While automated binning software and their combination produce prokaryotic bins in high-throughput, their manual refinement has been slow and sometimes difficult. Here, we present uBin, a GUI-based, standalone bin refiner that runs on all major operating platforms and was specifically designed for educational purposes. When applied to the public CAMI dataset, refinement of bins was able to improve 78.9% of bins by decreasing their contamination. We also applied the bin refiner as a standalone binner to public metagenomes from the International Space Station and demonstrate the recovery of near-complete genomes, whose replication indices indicate active proliferation of microbes in Earths lower orbit. uBin is an easy to install software for bin refinement, binning of simple metagenomes and communication of metagenomic results to other scientists and in classrooms. The software is open source and available under https://github.com/ProbstLab/uBin.

genomics↗