Environmentally-driven gene content convergence and the Bacillus phylogeny

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Genomics

Background:

• Bacillus species inhabit diverse environments, but the link between their ecological niche and metabolic potential is underexplored.
• Previous research proposed a monophyletic aquatic Bacillus group, though this has not been fully substantiated.
• Investigating environmental influences on bacterial evolution and adaptation is crucial for understanding microbial diversity.

Purpose of the Study:

• To investigate the evolutionary origins of aquatic Bacillus species using phylogenetic and phylogenomic analyses.
• To determine if environmental isolation influences the genetic content of Bacillus bacteria.
• To test for convergence in gene content among aquatic Bacillus species from different evolutionary lineages.

Main Methods:

• Phylogenetic and phylogenomic reconstruction of Bacillus strains.
• Hierarchical clustering based on functional gene content (proteomes).
• Comparative analysis of evolutionary history and environmental adaptation.

Main Results:

• Phylogenetic analysis revealed that aquatic Bacillus strains originate from multiple distinct evolutionary lineages, challenging the monophyletic aquatic group hypothesis.
• Clustering based on functional gene content grouped bacteria according to their isolation environment, indicating environmental influence.
• A clade of exclusively aquatic Bacillus was identified, but it differed from previously reported groups.

Conclusions:

• Aquatic Bacillus species exhibit polyphyletic evolutionary origins.
• Despite diverse origins, Bacillus species show convergence in gene content, suggesting environmental adaptation.
• Environmental factors play a significant role in shaping the genetic makeup of bacteria, irrespective of their evolutionary history.