Microbial divergence and evolution. The case of anammox bacteria

Area of Science:

• Microbial Evolution
• Bacterial Phylogenetics
• Biogeochemical Cycles

Background:

• Understanding species differentiation and microbial evolution is key to Earth's past and future.
• Anammox (anaerobic ammonium oxidation) bacteria, within Phylum Planctomycetota, represent a unique and ancient physiological group with limited known species.
• The hydrazine dehydrogenase (HDH) enzyme is central to the anammox pathway.

Purpose of the Study:

• To analyze the evolutionary trajectory of anammox bacteria using HDH as a model.
• To investigate the relationship between gene evolution, genome diversification, and species diversification in this group.
• To understand the phylogenetic origin and diversification patterns of anammox bacteria.

Main Methods:

• Phylogenetic analysis of hydrazine dehydrogenase (HDH) and 16S rRNA genes.
• Phylogenomic analysis, including GC content and codon usage profiling.
• Examination of bacterial consortia and potential for monospecific cultivation.

Main Results:

• HDH and 16S rRNA phylogenies support a monophyletic origin for anammox bacteria.
• Evolution of HDH genes correlates with the diversification of anammox clades, genomes, GC content, and codon usage.
• Anammox bacteria exhibit paralleled genome, gene, and species diversification from a common ancestor.

Conclusions:

• Microbial evolution in anammox bacteria demonstrates an ordered, vertical diversification throughout Earth's history.
• This group provides a clear model for understanding bacterial evolution, often obscured by complex prokaryotic phylogenies.
• Future microbial speciation may follow similar ordered diversification patterns observed in anammox bacteria.