Genome-Wide Identification of Essential Genes in the Invasive Streptococcus anginosus Strain
Abstract
Background
Streptococcus anginosus, part of theStreptococcus anginosusgroup (SAG), is a human commensal increasingly recognized as an opportunistic pathogen responsible for abscesses formation and infections, also invasive ones. Despite its growing clinical importance, the genetic determinants of its pathogenicity remain poorly understood.
Objectives
This study aimed to identify essential genes inS. anginosus980/01, a bloodstream isolate, under optimal laboratory conditions using a transposon mutagenesis combined with Transposon-Directed Insertion Site Sequencing (TraDIS).
Methods
A mutant library was generated using the ISS1transposon deliveredviathe thermosensitive plasmid pGh9:ISS1. Following transposition, insertions were mapped using Illumina sequencing and analyzed. Essential genes were identified based on the absence of insertions and statistical filtering.
Results
The library exhibited 98% genome saturation with over 130,000 unique insertion sites. Among 1,825 genes, 348 (19.1%) were essential, 1,446 non-essential, and 30 non-conclusive. Comparative analyses were performed withS. pyogenesMGAS5005 andS. agalactiaeA909. Similarly to the latter, essential genes were enriched in functions related to translation, transcription, and cell wall biosynthesis. However, 40 genes uniquely essential toS. anginosus980/01 were identified, suggesting unique survival strategies inS. anginosus.
Conclusions
This study presents the first genome-wide identification of essential genes forS. anginosus980/01, highlighting conserved and unique essential genes. These findings provide a basis for understanding its pathogenic potential and for identifying novel antimicrobial targets.
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