Change Is Good: Variations in Common Biological Mechanisms in the Epsilonproteobacterial Genera Campylobacter and Helicobacter

摘要

Among the currently described eubacterial phyla, the Proteobacteria represent the largest and one of the most diverse groups of organisms (237). This phylum consists of over 200 genera and contains the majority of Gram- negative species (237). The group consists of five subdivisions: Alpha-, Beta-, Gamma-, Delta-, and Epsilonproteobacteria. Although the subdivisions evolved from a common ancestor, the estimated divergence dates indicate that individual proteobacterial subdivisions branched separately and in a particular order, with the delta subdivision having branched first, approximately 2.38 billion years ago, followed by the epsilon, alpha, beta, and gamma subdivisions (237, 536).