Host-bacteria interactions: ecological and evolutionary insights from ancient, professional endosymbionts

Area of Science:

• Microbiology
• Evolutionary Biology
• Ecology

Background:

• Eukaryotic host-bacterial symbiont interactions are fundamental to ecological and evolutionary processes.
• Endosymbionts typically exhibit genome reduction and stable host relationships, though environmental factors can alter this dynamic.
• Deep-branching Intracellular Gammaproteobacteria (DIGs) represent an ancient and diverse group of endosymbionts.

Purpose of the Study:

• To review the effects of environmental changes on Deep-branching Intracellular Gammaproteobacteria (DIGs).
• To explore the distribution, genomic features, and ecological interactions of DIGs.
• To highlight the role of omics technologies in understanding DIGs.

Main Methods:

• Literature review of existing studies on DIGs and their hosts.
• Analysis of reported distribution patterns and abundance of DIGs in various biomes.
• Examination of the prevalence and variation of the type IVB secretion system in DIGs.

Main Results:

• DIGs are globally distributed but typically found at low abundance, predominantly in aquatic environments.
• Most DIGs possess a type IVB secretion system, crucial for host adaptation, with structural variations observed.
• Various microbial interactions in diverse environments can influence DIG populations.

Conclusions:

• Environmental changes play a significant role in shaping host-bacterial symbiosis, particularly for ancient groups like DIGs.
• The type IVB secretion system is a key adaptation in DIGs, though its specifics vary.
• Future omics research will enhance our understanding of DIGs from ecological, molecular, and evolutionary viewpoints.