Characteristics of a phylogenetically ambiguous, arsenic-oxidizing Thiomonas sp., Thiomonas arsenitoxydans strain 3As(T) sp nov

C.N.R.S., Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, Laboratoire de Chimie Bactérienne, UPR9043, 31 chemin Joseph Aiguier, 13402, Marseille, France.
Archives of Microbiology (Impact Factor: 1.67). 03/2011; 193(6):439-49. DOI: 10.1007/s00203-011-0684-y
Source: PubMed

ABSTRACT A moderately acidophilic, facultative chemoautotrophic, As(III)-oxidizing Thiomonas sp. (strain 3As(T)) was previously shown, on the basis of comparative 16S rRNA gene sequences, to be closely related to both Tm. perometabolis DSM 18570(T) and Tm. intermedia DSM 18155(T). While it had shared many physiological traits with Tm. intermedia (T), a mean DNA-DNA hybridization value (DDHV) of 47.2% confirmed that strain 3As(T) was not a strain of Tm. intermedia, though the situation with regard to Tm. perometabolis (DDHV previously determined as 72%) was more ambiguous. A comparative physiological and chemotaxonomic study of strain 3As(T) and Tm. perometabolis (T) was therefore carried out, together with multilocus sequence analysis (MLSA) of all three bacteria. Differences in fatty acid profiles and utilization of organic substrates supported the view that strain 3As(T) and Tm. perometabolis are distinct species, while MLSA showed a closer relationship between strain 3As(T) and Tm. intermedia (T) than between strain 3As(T) and Tm. perometabolis (T). These apparent contradictory conclusions were explained by differences in genome of these three bacteria, which are known to be highly flexible in Thiomonas spp. A novel species designation Thiomonas arsenitoxydans is proposed for strain 3As(T) (DSM 22701(T), CIP 110005(T)), which is nominated as the type strain of this species.

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Available from: Violaine Bonnefoy, Jul 18, 2014
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    • "Because the narGHJI operon was detected in the T. arsenitoxydans genomic sequence (Arsene-Ploetze et al. 2010), this electron acceptor could be nitrate, as already observed in other bacteria (Rhine et al. 2006; Hoeft et al. 2007; Oremland et al. 2009; Sun et al. 2010; Huang et al. 2012). Another possibility is that Cyc2 transfers the electrons to the NDH-1 complex via the bc 1 complex to reconstitute the reducing power necessary for anabolic processes, in particular CO 2 fixation, because T. arsenitoxydans is a facultative autotroph (Duquesne et al. 2008; Slyemi et al. 2011). The orf1 gene belonging to the aioBA operon is predicted to encode an ArsR/SmtB metal(loid)-responsive regulator. "
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    ABSTRACT: Thiomonas arsenitoxydans is an acidophilic and facultatively autotrophic bacterium that can grow by oxidizing arsenite to arsenate. A comparative genomic analysis showed that the T. arsenitoxydans aioBA cluster encoding the two subunits of arsenite oxidase is distinct from the other clusters, with two specific genes encoding a cytochrome c and a metalloregulator belonging to the ArsR/SmtB family. These genes are cotranscribed with aioBA, suggesting that these cytochromes c are involved in arsenite oxidation and that this operon is controlled by the metalloregulator. The growth of T. arsenitoxydans in the presence of thiosulfate and arsenite, or arsenate, is biphasic. Real-time PCR experiments showed that the operon is transcribed during the second growth phase in the presence of arsenite or arsenate, whereas antimonite had no effect. These results suggest that the expression of the aioBA operon of T. arsenitoxydans is regulated by the electron donor present in the medium, i.e., is induced in the presence of arsenic but is repressed by more energetic substrates. Our data indicate that the genetic organization and regulation of the aioBA operon of T. arsenitoxydans differ from those of the other arsenite oxidizers.
    Extremophiles 08/2013; 17(6). DOI:10.1007/s00792-013-0573-1 · 2.31 Impact Factor
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    • "Microbes primarily metabolize inorganic arsenic either for resistance or for energy generation. The transformations may involve oxidation, reduction, methylation or demethylation (Slyemi et al. 2011). "
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    ABSTRACT: Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H(2), H(2)S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels.
    Extremophiles 05/2012; 16(3):523-38. DOI:10.1007/s00792-012-0452-1 · 2.31 Impact Factor
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    • "and several amino acids, and are able to use fructose as a unique carbon source (Arsène-Ploetze et al., 2010; Slyemi et al., 2011). Interestingly, most of the secreted compounds contained nitrogen, which may have a key role in the ecosystems where E. mutabilis is found. "
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    ABSTRACT: Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited.
    The ISME Journal 01/2012; 6(7):1391-402. DOI:10.1038/ismej.2011.198 · 9.30 Impact Factor
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