Biology subjects

Nezam-Abadi, N.

Publications and source records attributed to Nezam-Abadi, N..

2 recordsLinked to original sources

bioRxiv2026

Ratatoskr: A tool for automated retrieval of taxonomic type strain sequences and metadata

Bacterial taxonomic type strains anchor species names to physical and genomic reference material, making them essential for reproducible and comparable prokaryotic research. While reference strains are often well-characterised through curated metadata, nomenclature histories, and sequence records, no single database holds up-to-date information on all these aspects, resulting in fragmented information. Gathering the complete set of information for a type strain is further complicated by inconsistencies in nomenclature between sources due to the often-numerous synonyms that can describe a single strain. As a result, collecting type strain data for taxonomic proposals and emendations can be an onerous task requiring extensive manual curation. To address this issue, we introduce Ratatoskr, a Python-based tool that automates the retrieval of sequences and metadata for bacterial taxonomic type strains. Ratatoskr facilitates this by collecting the latest type strain information of the List of Prokaryotic names with Standing in Nomenclature (LPSN) and using this information to query the BacDive and NCBI databases. By applying known taxonomic synonym information Ratatoskr is able to resolve cross-database inconsistencies and streamline the retrieval process. We show that through its use, Ratatoskr can obtain metadata and sequence data for type strains of bacteria within minutes to seconds, depending on the number of members within the requested taxon. By automating this retrieval, Ratatoskr provides fast, accurate, and readily shareable starting points for studies involving the use of taxonomic type strains and data, such as new taxonomic proposals or emendations. Data summaryRatatoskr was developed using Python 3 and is freely available at https://github.com/Fabian-Bastiaanssen/Ratatoskr under a GPL-3.0 licence.

bioinformatics↗

bioRxiv2023

Temperate gut phages are prevalent, diverse, and predominantly inactive

Large-scale metagenomic and data mining efforts have uncovered an expansive diversity of bacteriophages (phages) within the human gut1-3. These insights include broader phage populational dynamics such as temporal stability4, interindividual uniqueness5,6 and potential associations to specific disease states7,8. However, the functional understanding of phage-host interactions and their impacts within this complex ecosystem have been limited due to a lack of cultured isolates for experimental validation. Here we characterise 125 active prophages originating from 252 diverse human gut bacterial isolates using seven different induction conditions to substantially expand the experimentally validated temperate phage-host pairs originating from the human gut. Importantly, only 17% of computationally predicted prophages were induced with common induction agents and these exhibited distinct gene patterns compared to non-induced predictions. Active Bacteroidota prophages were among the most prevalent members of the gut virome, with extensive use of diversity generating retroelements and exhibiting broad host ranges. Moreover, active polylysogeny was present in 52% of studied gut lysogens and led to coordinated prophage induction across diverse conditions. This study represents a substantial expansion of experimentally validated gut prophages, providing key insights into their diversity and genetics, including a genetic pathway for prophage domestication and demonstration that differential induction was complex and influenced by divergent prophage integration sites. More broadly, it highlights the importance of experimental validation alongside genomic based computational prediction to enable further functional understanding of these commensal viruses within the human gut.

microbiology↗