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Autotrophic, sulfur-oxidizing actinobacteria in acidic environments
Paul R Norris1, Carol S Davis-Belmar, Carly F Brown
1School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK. P.R.Norris@warwick.ac.uk
Extremophiles : Life Under Extreme Conditions
|February 11, 2011
Summary
Novel acidophilic actinobacteria, named "Acidithiomicrobium" species, were discovered in geothermal environments. These sulfur-oxidizing bacteria exhibit ferrous iron oxidation and possess unique Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gene lineages.
Area of Science:
- Microbiology
- Geochemistry
- Genetics
Background:
- Novel actinobacteria discovered in geothermal environments demonstrate autotrophic growth using sulfur as an energy source.
- These acidophilic bacteria, referred to as "Acidithiomicrobium" species, are phylogenetically related to Acidimicrobium ferrooxidans.
- Both "Acidithiomicrobium" and Acidimicrobium ferrooxidans share the capability for ferrous iron oxidation.
Purpose of the Study:
- To characterize novel sulfur-oxidizing actinobacteria from geothermal sources.
- To investigate the genetic basis of carbon dioxide fixation in these organisms, particularly the acquisition of Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) genes.
- To explore the evolutionary implications of horizontal gene transfer events.
Main Methods:
- Isolation and cultivation of novel actinobacteria from geothermal environments.
- Analysis of 16S rRNA gene sequences to determine phylogenetic relationships.
- Investigation of metabolic capabilities, including autotrophic growth on sulfur and ferrous iron oxidation.
- Identification and characterization of RuBisCO-encoding genes and their evolutionary origins.
Main Results:
- "Acidithiomicrobium" species were identified as novel, acidophilic, sulfur-oxidizing actinobacteria from geothermal environments.
- These bacteria possess RuBisCO genes closely related to those of Acidimicrobium ferrooxidans and Acidithiobacillus ferrooxidans, suggesting horizontal gene transfer.
- Evidence suggests that Acidimicrobium ferrooxidans acquired its RuBisCO genes from proteobacteria, such as Acidithiobacillus ferrooxidans.
- "Acidithiomicrobium" species possess additional, distinct RuBisCO gene lineages.
Conclusions:
- "Acidithiomicrobium" represents a new genus of sulfur-oxidizing, acidophilic actinobacteria.
- The study provides evidence for horizontal gene transfer of RuBisCO genes between proteobacteria and actinobacteria.
- The findings contribute to understanding microbial adaptation in extreme geothermal environments and the evolution of metabolic pathways.
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