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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

Effect of urea degradation on cell viability. Viability and pH were measured during the growth of the Thiomonas strains in m126 medium in the absence and presence of urea. Error bars indicate standard deviations based on triplicate cultures.
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Figure 5: Effect of urea degradation on cell viability. Viability and pH were measured during the growth of the Thiomonas strains in m126 medium in the absence and presence of urea. Error bars indicate standard deviations based on triplicate cultures.

Mentions: The effects of urea degradation on acid tolerance were further tested in three strains, CB2, 3As, and K12. During the growth of these three strains in m126 in the absence of urea, the pH of the culture medium dropped to approximately 3.0 or less within 24 h, and stabilized after 50 h (Figure 5). The viability of the cells decreased rapidly, probably due to this pH decrease. In the presence of urea, the pH of the CB2 growth medium remained at a value of approximately 6 because of the production of ammonia and carbonic acid during the urea degradation process, whereas in both K12 and 3As, the pH dropped to 3 even in the presence of urea in the growth medium (Figure 5). CB2 cells were less viable when grown without than with urea (Figure 5). The viability of 3As and K12 was similar whether cells were grown in the presence or absence of urea, as well as being similar to that of CB2 cells grown without any urea (Figure 5). These data show that the urea degradation activity of CB2 in synthetic media contributed to preventing the acidification of the medium during cell growth and enabled CB2 to survive more efficiently than 3As and K12 under the conditions tested here. The acid resistance conferred on CB2 by urease activity may result from a similar mechanism to that found to occur in the human pathogen H. pylori, which resists acid in the human stomach by degrading urea into carbonic acid and ammonia, the deprotonated and protonated forms of which are in a state of equilibrium (Athmann et al., 2000). It was then proposed to test whether this activity played a role when this bacterium was incubated under AMD conditions.


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)

Effect of urea degradation on cell viability. Viability and pH were measured during the growth of the Thiomonas strains in m126 medium in the absence and presence of urea. Error bars indicate standard deviations based on triplicate cultures.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Effect of urea degradation on cell viability. Viability and pH were measured during the growth of the Thiomonas strains in m126 medium in the absence and presence of urea. Error bars indicate standard deviations based on triplicate cultures.
Mentions: The effects of urea degradation on acid tolerance were further tested in three strains, CB2, 3As, and K12. During the growth of these three strains in m126 in the absence of urea, the pH of the culture medium dropped to approximately 3.0 or less within 24 h, and stabilized after 50 h (Figure 5). The viability of the cells decreased rapidly, probably due to this pH decrease. In the presence of urea, the pH of the CB2 growth medium remained at a value of approximately 6 because of the production of ammonia and carbonic acid during the urea degradation process, whereas in both K12 and 3As, the pH dropped to 3 even in the presence of urea in the growth medium (Figure 5). CB2 cells were less viable when grown without than with urea (Figure 5). The viability of 3As and K12 was similar whether cells were grown in the presence or absence of urea, as well as being similar to that of CB2 cells grown without any urea (Figure 5). These data show that the urea degradation activity of CB2 in synthetic media contributed to preventing the acidification of the medium during cell growth and enabled CB2 to survive more efficiently than 3As and K12 under the conditions tested here. The acid resistance conferred on CB2 by urease activity may result from a similar mechanism to that found to occur in the human pathogen H. pylori, which resists acid in the human stomach by degrading urea into carbonic acid and ammonia, the deprotonated and protonated forms of which are in a state of equilibrium (Athmann et al., 2000). It was then proposed to test whether this activity played a role when this bacterium was incubated under AMD conditions.

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