Limits...
Thiomonas sp. CB2 is able to degrade urea and promote toxic metal precipitation in acid mine drainage waters supplemented with urea.

Farasin J, Andres J, Casiot C, Barbe V, Faerber J, Halter D, Heintz D, Koechler S, Lièvremont D, Lugan R, Marchal M, Plewniak F, Seby F, Bertin PN, Arsène-Ploetze F - Front Microbiol (2015)

Bottom Line: The urease activity of Thiomonas sp.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire Génétique Moléculaire, Génomique et Microbiologie, UMR7156, Université de Strasbourg - Centre National de la Recherche Scientifique, Institut de Botanique Strasbourg, France.

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.

No MeSH data available.


Related in: MedlinePlus

Analysis of precipitates' composition. SEM photographs and microanalytical X-ray graphs of precipitates. These were obtained with AMD-impacted water supplemented (A) with 1 g.L−1 urea after incubating CB2 for 4 days and (B) after incubating 10 U of urease in AMD-impacted water supplemented with 1 g.L−1 urea for 1 day, respectively. White arrows on the photographs show spots on which the X-ray microanalyses were conducted to obtain the graphs presented below. Since the magnesium X-ray K lines interfered with the arsenic L lines around 1250–1300 eV, the presence of As was confirmed by checking its K lines at higher energy levels. Silicon in the second graph and carbon in the first and third ones originate from the supports used in these studies. Pictures and graphs are representative of at least three points analyzed. These graphs show that aluminum is present in the precipitate only under the conditions where urea degradation activity was possible. Controls were also performed with (C) urea added alone, (D) no urea added (E) with inactivated urease, and (F) with urease but no urea.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4585258&req=5

Figure 8: Analysis of precipitates' composition. SEM photographs and microanalytical X-ray graphs of precipitates. These were obtained with AMD-impacted water supplemented (A) with 1 g.L−1 urea after incubating CB2 for 4 days and (B) after incubating 10 U of urease in AMD-impacted water supplemented with 1 g.L−1 urea for 1 day, respectively. White arrows on the photographs show spots on which the X-ray microanalyses were conducted to obtain the graphs presented below. Since the magnesium X-ray K lines interfered with the arsenic L lines around 1250–1300 eV, the presence of As was confirmed by checking its K lines at higher energy levels. Silicon in the second graph and carbon in the first and third ones originate from the supports used in these studies. Pictures and graphs are representative of at least three points analyzed. These graphs show that aluminum is present in the precipitate only under the conditions where urea degradation activity was possible. Controls were also performed with (C) urea added alone, (D) no urea added (E) with inactivated urease, and (F) with urease but no urea.

Mentions: The pH increase observed here may have induced the co-precipitation of other metals together with Fe under these experimental conditions. Using inductively coupled plasma-mass spectrometry (ICP-MS, Table 2) and X-ray microanalysis (Figure 8), we established that in samples where urea degradation had occurred (samples inoculated with CB2 in the presence of urea), the soluble iron, arsenic, and aluminum concentrations were lower than in the other samples tested. In addition, high amounts of these elements were detected in the precipitates obtained from these samples (Table 2; Figure 8). Fe(III) precipitation probabaly causes the co-precipitation of arsenic, as previously found to occur in AMD-impacted waters (Casiot et al., 2003; Morin et al., 2003; Duquesne et al., 2008). Previous studies have shown that Thiomonas strains express arsenite oxidases in AMD-impacted creek waters (Bertin et al., 2011). As(III) may be oxidized into As(V), which is less soluble and precipitates with Fe(III) more efficiently than As(III) under these conditions (Casiot et al., 2003; Morin et al., 2003; Cheng et al., 2009; Maillot et al., 2013). Thiomonas sp. CB2 oxidizes As(III) in the presence of organic compounds (Bryan et al., 2009), and we observed in the present study that this bacterium is also able to oxidize As(III) in the presence of urea in m126 medium (Figure 9). Therefore, to test whether CB2 is able to oxidize arsenite in AMD-impacted water, the concentrations of As(III) and As(V) present in the soluble fraction were measured using ICP-AES or GC-MS. The concentrations of these two forms of arsenic decreased under all the conditions tested (Figure 10). No As(V) accumulation was observed in the soluble phase because As(V) is more efficiently adsorbed by Fe precipitates than As(III) in AMD-impacted water (Morin et al., 2003; Cheng et al., 2009; Maillot et al., 2013). These explanations are consistent with results obtained in previous studies on the geochemical processes underlying iron and arsenic solubility in AMD (Cheng et al., 2009; Klein et al., 2014). All in all, the present findings indicate that As(III) may be oxidized into As(V) and precipitated with iron more readily when urease activity is possible.


Thiomonas sp. CB2 is able to degrade urea and promote toxic metal precipitation in acid mine drainage waters supplemented with urea.

Farasin J, Andres J, Casiot C, Barbe V, Faerber J, Halter D, Heintz D, Koechler S, Lièvremont D, Lugan R, Marchal M, Plewniak F, Seby F, Bertin PN, Arsène-Ploetze F - Front Microbiol (2015)

Analysis of precipitates' composition. SEM photographs and microanalytical X-ray graphs of precipitates. These were obtained with AMD-impacted water supplemented (A) with 1 g.L−1 urea after incubating CB2 for 4 days and (B) after incubating 10 U of urease in AMD-impacted water supplemented with 1 g.L−1 urea for 1 day, respectively. White arrows on the photographs show spots on which the X-ray microanalyses were conducted to obtain the graphs presented below. Since the magnesium X-ray K lines interfered with the arsenic L lines around 1250–1300 eV, the presence of As was confirmed by checking its K lines at higher energy levels. Silicon in the second graph and carbon in the first and third ones originate from the supports used in these studies. Pictures and graphs are representative of at least three points analyzed. These graphs show that aluminum is present in the precipitate only under the conditions where urea degradation activity was possible. Controls were also performed with (C) urea added alone, (D) no urea added (E) with inactivated urease, and (F) with urease but no urea.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585258&req=5

Figure 8: Analysis of precipitates' composition. SEM photographs and microanalytical X-ray graphs of precipitates. These were obtained with AMD-impacted water supplemented (A) with 1 g.L−1 urea after incubating CB2 for 4 days and (B) after incubating 10 U of urease in AMD-impacted water supplemented with 1 g.L−1 urea for 1 day, respectively. White arrows on the photographs show spots on which the X-ray microanalyses were conducted to obtain the graphs presented below. Since the magnesium X-ray K lines interfered with the arsenic L lines around 1250–1300 eV, the presence of As was confirmed by checking its K lines at higher energy levels. Silicon in the second graph and carbon in the first and third ones originate from the supports used in these studies. Pictures and graphs are representative of at least three points analyzed. These graphs show that aluminum is present in the precipitate only under the conditions where urea degradation activity was possible. Controls were also performed with (C) urea added alone, (D) no urea added (E) with inactivated urease, and (F) with urease but no urea.
Mentions: The pH increase observed here may have induced the co-precipitation of other metals together with Fe under these experimental conditions. Using inductively coupled plasma-mass spectrometry (ICP-MS, Table 2) and X-ray microanalysis (Figure 8), we established that in samples where urea degradation had occurred (samples inoculated with CB2 in the presence of urea), the soluble iron, arsenic, and aluminum concentrations were lower than in the other samples tested. In addition, high amounts of these elements were detected in the precipitates obtained from these samples (Table 2; Figure 8). Fe(III) precipitation probabaly causes the co-precipitation of arsenic, as previously found to occur in AMD-impacted waters (Casiot et al., 2003; Morin et al., 2003; Duquesne et al., 2008). Previous studies have shown that Thiomonas strains express arsenite oxidases in AMD-impacted creek waters (Bertin et al., 2011). As(III) may be oxidized into As(V), which is less soluble and precipitates with Fe(III) more efficiently than As(III) under these conditions (Casiot et al., 2003; Morin et al., 2003; Cheng et al., 2009; Maillot et al., 2013). Thiomonas sp. CB2 oxidizes As(III) in the presence of organic compounds (Bryan et al., 2009), and we observed in the present study that this bacterium is also able to oxidize As(III) in the presence of urea in m126 medium (Figure 9). Therefore, to test whether CB2 is able to oxidize arsenite in AMD-impacted water, the concentrations of As(III) and As(V) present in the soluble fraction were measured using ICP-AES or GC-MS. The concentrations of these two forms of arsenic decreased under all the conditions tested (Figure 10). No As(V) accumulation was observed in the soluble phase because As(V) is more efficiently adsorbed by Fe precipitates than As(III) in AMD-impacted water (Morin et al., 2003; Cheng et al., 2009; Maillot et al., 2013). These explanations are consistent with results obtained in previous studies on the geochemical processes underlying iron and arsenic solubility in AMD (Cheng et al., 2009; Klein et al., 2014). All in all, the present findings indicate that As(III) may be oxidized into As(V) and precipitated with iron more readily when urease activity is possible.

Bottom Line: The urease activity of Thiomonas sp.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire Génétique Moléculaire, Génomique et Microbiologie, UMR7156, Université de Strasbourg - Centre National de la Recherche Scientifique, Institut de Botanique Strasbourg, France.

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.

No MeSH data available.


Related in: MedlinePlus