Phylogenetic and genetic variation among Fe(II)-oxidizing acidithiobacilli supports the view that these comprise multiple species with different ferrous iron oxidation pathways.
Autotrophic acidophilic iron- and sulfur-oxidizing bacteria of the genus Acidithiobacillus constitute a heterogeneous taxon encompassing a high degree of diversity at the phylogenetic and genetic levels, though currently only two species are recognized (Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivorans). One of the major functional disparities concerns the biochemical mechanisms of iron and sulfur oxidation, with discrepancies reported in the literature concerning the genes and proteins involved in these processes. These include two types of high-potential iron-sulfur proteins (HiPIPs): (i) Iro, which has been described as the iron oxidase; and (ii) Hip, which has been proposed to be involved in the electron transfer between sulfur compounds and oxygen. In addition, two rusticyanins have been described: (i) rusticyanin A, encoded by the rusA gene and belonging to the well-characterized rus operon, which plays a central role in the iron respiratory chain; and (ii) rusticyanin B, a protein to which no function has yet been ascribed. Data from a multilocus sequence analysis of 21 strains of Fe(II)-oxidizing acidithiobacilli obtained from public and private collections using five phylogenetic markers showed that these strains could be divided into four monophyletic groups. These divisions correlated not only with levels of genomic DNA hybridization and phenotypic differences among the strains, but also with the types of rusticyanin and HiPIPs that they harbour. Taken together, the data indicate that Fe(II)-oxidizing acidithiobacilli comprise at least four distinct taxa, all of which are able to oxidize both ferrous iron and sulfur, and suggest that different iron oxidation pathways have evolved in these closely related bacteria.
Amouric
Agnès
A
Laboratoire de Chimie Bactérienne, UPR-CNRS 9043, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 chemin Joseph Aiguier, 13009, Marseille, France.
Brochier-Armanet
Céline
C
Laboratoire de Chimie Bactérienne, UPR-CNRS 9043, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 chemin Joseph Aiguier, 13009, Marseille, France.
Johnson
D Barrie
DB
School of Biological Sciences, College of Natural Sciences, Bangor University, Bangor LL57 2UW, UK.
Bonnefoy
Violaine
V
Laboratoire de Chimie Bactérienne, UPR-CNRS 9043, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 chemin Joseph Aiguier, 13009, Marseille, France.
Hallberg
Kevin B
KB
School of Biological Sciences, College of Natural Sciences, Bangor University, Bangor LL57 2UW, UK.
D042763:Acidithiobacillus / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005296:Ferrous Compounds / Q000378:metabolism*; D023061:Gene Order; D020459:Genes, rRNA; D014644:Genetic Variation; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D009693:Nucleic Acid Hybridization; D010084:Oxidation-Reduction; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013455:Sulfur / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D005296:Ferrous Compounds; D013455:Sulfur