Identifying essential genes in Schaalia odontolytica using a saturated transposon library

Area of Science:

• Microbiology and Genomics
• Oral Microbiome Research
• Bacterial Genetics

Background:

• The obligate epibiotic-parasitic relationship between Schaalia odontolytica (XH001) and Nanosynbacter lyticus (TM7x) is poorly understood due to limited genetic tools for TM7x.
• Previous research focused on genomic and transcriptomic analyses of XH001 post-infection, lacking direct genetic dissection of the interaction.
• XH001 is an early colonizer of oral biofilms, and understanding its interaction with TM7x is crucial for oral microbiome dynamics.

Purpose of the Study:

• To expand the genetic toolset for S. odontolytica (XH001) to facilitate deeper investigation of its relationship with N. lyticus (TM7x).
• To develop and apply high-throughput transposon insertion sequencing (Tn-seq) for genetic screening in XH001.
• To identify putatively essential genes in XH001 under laboratory conditions.

Main Methods:

• Generation of a highly saturated transposon insertion sequencing (Tn-seq) library for S. odontolytica (XH001), comprising nearly 660,000 unique insertion mutations.
• Application of Tn-seq to screen for genes essential for XH001 growth under laboratory conditions.
• Bioinformatic analysis to identify putatively essential genes based on transposon insertion patterns.

Main Results:

• A comprehensive Tn-seq library was successfully constructed, achieving high saturation with insertions every 2-3 nucleotides.
• A total of 203 genes, representing 10.5% of the XH001 genome, were identified as putatively essential.
• The developed Tn-seq methodology provides a powerful tool for future genetic studies in XH001.

Conclusions:

• The developed Tn-seq library and methodology enable efficient screening for essential genes in S. odontolytica (XH001).
• Identification of essential genes provides insights into XH001's basic growth requirements.
• This genetic toolset will be instrumental in future research to elucidate the molecular mechanisms underlying the dependence of N. lyticus (TM7x) on its basibiont XH001.