Limits...
The role of Carboxydothermus hydrogenoformans in the conversion of calcium phosphate from amorphous to crystalline state.

Haddad M, Vali H, Paquette J, Guiot SR - PLoS ONE (2014)

Bottom Line: The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm.Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor.The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process.

View Article: PubMed Central - PubMed

Affiliation: Energy, Mining and Environment Portfolio, National Research Council Canada, Montreal, Quebec, Canada ; Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada.

ABSTRACT
Two previously unknown modes of biomineralization observed in the presence of Carboxydothermus hydrogenoformans are presented. Following the addition of NaHCO3 and the formation of an amorphous calcium phosphate precipitate in a DSMZ medium inoculated with C. hydrogenoformans, two distinct crystalline solids were recovered after 15 and 30 days of incubation. The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm. The second solid occurred as 30-50 nm nanorods that were found scattered among the organic products of bacterial lysis. The biphasic mixture of solids was clearly dominated by the first phase. The X-ray diffractometry (XRD) peaks and Fourier transform infrared spectroscopy (FTIR) spectrum of this biphasic material consistently showed features characteristic of Mg-whitlockite. No organic content or protein could be identified by dissolving the solids. In both cases, the mode of biomineralization appears to be biologically induced rather than biologically controlled. Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor. The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process.

Show MeSH

Related in: MedlinePlus

TEM imaging of the inoculated DSMZ medium sampled after 6 days of culture.A to D show magnification of cell lysis and spatial association of the lysed vesicle of C. hydrogenoformans and the interpreted HAP.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3935887&req=5

pone-0089480-g010: TEM imaging of the inoculated DSMZ medium sampled after 6 days of culture.A to D show magnification of cell lysis and spatial association of the lysed vesicle of C. hydrogenoformans and the interpreted HAP.

Mentions: Ultrathin sections of samples obtained from the time course experiment shed additional light on the evolution of the amorphous precipitate. Because of its high solubility, the only evidence of the solid granules produced in the sterile DSMZ medium were holes left in the epoxy matrix (Figure 9, A). The granules were dissolved during the sectioning process, which exposed them to low-pH water. After 3 days of C. hydrogenoformans growth, a nanocrystalline phase composed of 30–50 nm rod-like crystals, distinct from the previously characterized whitlockite, was observed (Figure 10, D). These nanorods resembled hydroxyapatite produced by bacteria and mammalian cells such as bone and calcified tissue [35]. In this sample, well-preserved bacteria were observed (Figure 9, B). Backscatter analysis was carried out on the cutting face of the epoxy blocks used for the sectioning. Distribution and chemical composition of the amorphous CaP precursor confirmed the results previously obtained with TEM and SEM analysis (Figure 11, A, B). No traces of CaP material were detected in the epoxy matrix for the sample recovered after 15 days from the sterile DSMZ medium (Figure 11, C). The backscatter analysis of the blocks containing the sample recovered after 15 days of incubation in an inoculated DSMZ medium (Figure 11, D) revealed a presence both larger crystals and the chemical signature of a CaP material dispersed throughout the matrix, which could be mixture of disaggregated granular whitlockite and nanorods (Figure 11, E, F). With time, there was increasing visible evidence for bacterial lysis (Figure 10) and the nanorods were always associated with those degraded bacterial remnants (Figure 10, C, D). Disruption of cytoplasmic membrane led to the formation of vesicles that could have served as nucleation site for the precipitation of hydroxyapatite (Figure 10, A, B).


The role of Carboxydothermus hydrogenoformans in the conversion of calcium phosphate from amorphous to crystalline state.

Haddad M, Vali H, Paquette J, Guiot SR - PLoS ONE (2014)

TEM imaging of the inoculated DSMZ medium sampled after 6 days of culture.A to D show magnification of cell lysis and spatial association of the lysed vesicle of C. hydrogenoformans and the interpreted HAP.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3935887&req=5

pone-0089480-g010: TEM imaging of the inoculated DSMZ medium sampled after 6 days of culture.A to D show magnification of cell lysis and spatial association of the lysed vesicle of C. hydrogenoformans and the interpreted HAP.
Mentions: Ultrathin sections of samples obtained from the time course experiment shed additional light on the evolution of the amorphous precipitate. Because of its high solubility, the only evidence of the solid granules produced in the sterile DSMZ medium were holes left in the epoxy matrix (Figure 9, A). The granules were dissolved during the sectioning process, which exposed them to low-pH water. After 3 days of C. hydrogenoformans growth, a nanocrystalline phase composed of 30–50 nm rod-like crystals, distinct from the previously characterized whitlockite, was observed (Figure 10, D). These nanorods resembled hydroxyapatite produced by bacteria and mammalian cells such as bone and calcified tissue [35]. In this sample, well-preserved bacteria were observed (Figure 9, B). Backscatter analysis was carried out on the cutting face of the epoxy blocks used for the sectioning. Distribution and chemical composition of the amorphous CaP precursor confirmed the results previously obtained with TEM and SEM analysis (Figure 11, A, B). No traces of CaP material were detected in the epoxy matrix for the sample recovered after 15 days from the sterile DSMZ medium (Figure 11, C). The backscatter analysis of the blocks containing the sample recovered after 15 days of incubation in an inoculated DSMZ medium (Figure 11, D) revealed a presence both larger crystals and the chemical signature of a CaP material dispersed throughout the matrix, which could be mixture of disaggregated granular whitlockite and nanorods (Figure 11, E, F). With time, there was increasing visible evidence for bacterial lysis (Figure 10) and the nanorods were always associated with those degraded bacterial remnants (Figure 10, C, D). Disruption of cytoplasmic membrane led to the formation of vesicles that could have served as nucleation site for the precipitation of hydroxyapatite (Figure 10, A, B).

Bottom Line: The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm.Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor.The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process.

View Article: PubMed Central - PubMed

Affiliation: Energy, Mining and Environment Portfolio, National Research Council Canada, Montreal, Quebec, Canada ; Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada.

ABSTRACT
Two previously unknown modes of biomineralization observed in the presence of Carboxydothermus hydrogenoformans are presented. Following the addition of NaHCO3 and the formation of an amorphous calcium phosphate precipitate in a DSMZ medium inoculated with C. hydrogenoformans, two distinct crystalline solids were recovered after 15 and 30 days of incubation. The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm. The second solid occurred as 30-50 nm nanorods that were found scattered among the organic products of bacterial lysis. The biphasic mixture of solids was clearly dominated by the first phase. The X-ray diffractometry (XRD) peaks and Fourier transform infrared spectroscopy (FTIR) spectrum of this biphasic material consistently showed features characteristic of Mg-whitlockite. No organic content or protein could be identified by dissolving the solids. In both cases, the mode of biomineralization appears to be biologically induced rather than biologically controlled. Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor. The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process.

Show MeSH
Related in: MedlinePlus