Evolutionary histories of microbial calcification-associated genes across the tree of life.

High-sequence-coverage calcyanin homologs are restricted to oxygenic cyanobacteria and fit vertical inheritance within seven families, suggesting a possible origin in a Cyanobacteriia ancestor.

• Why it matters: Microbial calcification shapes carbonate mineral formation and the global carbon cycle, but the genetic basis and deep evolutionary history of calcification-associated genes across Bacteria and Archaea remain unclear.
• What they did: A large-scale survey analyzed an intracellular calcification marker (calcyanin) and two calcification-associated genes (carbonic anhydrase and urease) across Bacteria and Archaea using phylogenetic and structural analyses.
• The result: Carbonic anhydrase genes show independent origins of the α-, β-, and γ-classes with extensive inter-phylum and possible inter-domain HGT, while urease genes likely originated in Pseudomonadota or Cyanobacteriota.