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


A moderately acidophilic, facultative chemoautotrophic, As(III)-oxidizing Thiomonas sp. (strain 3AsT) was previously shown, on the basis of comparative 16S rRNA gene sequences, to be closely related to both Tm. perometabolis DSM 18570T and Tm. intermedia DSM 18155T. While it had shared many physiological traits with Tm. intermedia
T, a mean DNA–DNA hybridization value (DDHV) of 47.2% confirmed that strain 3AsT 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 3AsT 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 3AsT and Tm. perometabolis are distinct species, while MLSA showed a closer relationship between strain 3AsT and Tm. intermedia
T than between strain 3AsT 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 3AsT (DSM 22701T, CIP 110005T), 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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    • "Although acid mine drainage (AMD) environments are highly toxic to most living organisms due to the acidic conditions and the presence of elements such as arsenic, a stable microbial community composed of bacteria, archaea, and protists has been known for several years to inhabit the AMD-impacted Reigous creek near Carnoulès (France; Bruneel et al., 2003, 2006, 2011; Duquesne et al., 2003, 2008; Bryan et al., 2009; Halter et al., 2011; Slyemi et al., 2011; Volant et al., 2012). Various Thiomonas bacteria isolated from this river were previously characterized, and it has been suggested that by oxidizing arsenite, Thiomonas strains may promote the sorption of arsenic by iron oxides and their coprecipitation, resulting in a natural process of arsenic attenuation (Bruneel et al., 2003; Morin et al., 2003; Duquesne et al., 2008; Bryan et al., 2009; Arsène-Ploetze et al., 2010; Egal et al., 2010; Slyemi et al., 2011, 2013). The survival of these Thiomonas bacteria probably involves several processes. "
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    ABSTRACT: The acid mine drainage (AMD) in Carnoulès (France) is characterized by the presence of toxic metals such as arsenic. Several bacterial strains belonging to the Thiomonas genus, which were isolated from this AMD, are able to withstand these conditions. Their genomes carry several genomic islands (GEIs), which are known to be potentially advantageous in some particular ecological niches. This study focused on the role of the "urea island" present in the Thiomonas CB2 strain, which carry the genes involved in urea degradation processes. First, genomic comparisons showed that the genome of Thiomonas sp. CB2, which is able to degrade urea, contains a urea genomic island which is incomplete in the genome of other strains showing no urease activity. The urease activity of Thiomonas sp. CB2 enabled this bacterium to maintain a neutral pH in cell cultures in vitro and prevented the occurrence of cell death during the growth of the bacterium in a chemically defined medium. In AMD water supplemented with urea, the degradation of urea promotes iron, aluminum and arsenic precipitation. Our data show that ureC was expressed in situ, which suggests that the ability to degrade urea may be expressed in some Thiomonas strains in AMD, and that this urease activity may contribute to their survival in contaminated environments.
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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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    • "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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