Saccharibacteria (TM7) in the Human Oral Microbiome.

Area of Science:

• Microbiology
• Oral Microbiome Research
• Bacterial Symbiosis

Background:

• Saccharibacteria (formerly TM7) are ubiquitous in the human oral microbiome but poorly understood due to cultivation challenges.
• Recent findings show high 16S rRNA diversity and associations with oral diseases.
• Their physiology, lifestyle, and role in health and disease remain largely elusive.

Purpose of the Study:

• To review current knowledge on the diversity and unique biology of Saccharibacteria.
• To highlight insights gained from the cultivation and characterization of Nanosynbacter lyticus TM7x.
• To explore the ecological impact of Saccharibacteria on the oral microbiome.

Main Methods:

• Review of existing literature on Saccharibacteria (TM7) and Nanosynbacter lyticus TM7x.
• Analysis of genomic data and observed interactions between TM7x and its host bacteria.
• Examination of the impact of TM7x on host physiology, growth, and abundance.

Main Results:

• Nanosynbacter lyticus TM7x is the first cultivated Saccharibacteria strain, an ultrasmall obligate parasite of oral bacteria.
• TM7x possesses a reduced genome, lacks essential biosynthetic pathways, and relies on its host.
• Dynamic reciprocal interactions occur between TM7x and its host, with potential for host cell killing under certain conditions.

Conclusions:

• Saccharibacteria significantly influence oral microbial ecology by modulating host bacteria.
• They impact microbiome structure, function, and host abundance through physiological changes and direct killing.
• Further research into diverse, uncharacterized Saccharibacteria is warranted given their prevalence and unique biology.