Molecular Systematics of the Genus Acidithiobacillus: Insights into the Phylogenetic Structure and Diversification of the Taxon

The genus Acidithiobacillus, which we covered earlier in our blog, has been subject of study by researchers all over the world for almost 100 years now. Although A. ferrooxidans is probably the best known member of the group, it is A. thiooxidans who was first described 1. Originally characterized in 1922, this sulfur-oxidizing microorganism is the type species of the group, which now comprises seven validated species, the last one formally described last year 2.

Members of the genus have been isolated all around the world in a great variety of natural and industrial settings, including acid rock drainages, sulfur springs, sulfidic caves, ore concentrates, leaching mine solutions, and so on. These sites are characterized by a varying range of physicochemical characteristics, including redox potentials, heavy metal concentrations and pH, among others. Hence, Acidithiobacillus isolates exhibit a wide set of phenotypic adaptations and distinctive genetic traits that make it really interesting to study them.

Over the years the number of strains and sequence clones that have been obtained has raised steadily, making their analysis somewhat difficult. In fact, many isolates remain unclassified at the species level and several conflicting specific assignments have been detected in public databases. This raised the necessity of further scrutiny of the current status of taxon and the evolutionary relations among its members.

In our last paper, we revise the phylogenetic relationships within this species complex and determine the phylogenetic species boundaries using three different typing approaches with varying degrees of resolution: 16S rRNA gene-based ribotyping, oligotyping, and multi-locus sequencing analysis (MLSA). Our work acknowledges their inherent diversity of the taxon, suggests the existence of unrecognized species (and probably also a new genus), and provides a new phylogenetic framework for those fond of the acidithiobacilli.

Harold Nuñez, Ana Moya-Beltrán et. al. Molecular Systematics of the Genus Acidithiobacillus: Insights into the Phylogenetic Structure and Diversification of the Taxon. Front. Microbiol. January 2017.

 

Post by Harold Nuñez

Edited by Raquel Quatrini


References

  1. Waksman, S. A., and Joffe, J. S. Microorganisms concerned in the oxidation of sulfur in the soil: Thiobacillus thiooxidans, a new sulfur-oxidizing organism isolated from the soil. J. Bacteriol. 7, 239–256 (1922). Back to text
  2. Falagán, C., and Johnson, D. B. Acidithiobacillus ferriphilus sp. nov., a facultatively anaerobic iron- and sulfur-metabolizing extreme acidophile. Int. J. Syst. Evol. Microbiol. 66, 206 (2016). doi: 10.1099/ijsem.0. 000698. Back to text
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