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Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats.

De Wit R, Gautret P, Bettarel Y, Roques C, Marlière C, Ramonda M, Nguyen Thanh T, Tran Quang H, Bouvier T - PLoS ONE (2015)

Bottom Line: Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses.Nucleic acid staining revealed that they contain DNA or RNA.In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 10(9) viruses per g of calcite.

View Article: PubMed Central - PubMed

Affiliation: Centre for Marine Biodiversity, Exploitation and Conservation (MARBEC),Université de Montpellier, CNRS, IRD, Ifremer, Place Eugène Bataillon, Case 093, 34095, Montpellier, France.

ABSTRACT
Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake "La Salada de Chiprana", Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>10(10) viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 10(9) viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as "nanobacteria" and that viruses may play a role in initiating calcification.

No MeSH data available.


Related in: MedlinePlus

Virus observed in different depth layers (see below) and different fractions of the microbial mat dominated by diatoms, Coleofasciculus chthonoplastes, and Chloroflexus-like bacteria (CLB), sampled in March 2007.Left panel (A): Virus counts in the extracted water fraction (pore water and water soaked into the extracellular polymer matrix). Right panel (B): Virus attached to solid organic and mineral matter. (circles = without acidification, squares = after 10 min of acidification, see Methods). Description of the different layers: I: the top layer from 0 to 0.8 ± 0.2 mm depth, comprised dense populations of diatoms of the genera: Frustula, Cymbella, Denticula, Nitzschia and few bundles of C. chthonoplastes and filaments of CLB; II: layer from 0.8 ± 0.2 mm to 1.5 ± 0.2 mm depth that separated very well from the top layer and comprised lesser densities of diatoms with high quantities biogenic high-Mg calcite grains (cf. Fig 3); III: locally a very fine layer was observed at 1.5 ± 0.3 mm depth that was particularly enriched in biogenic high-Mg calcite embedded in an organic matrix; IV: A layer located below the high densities of biogenic calcium carbonate crystals occurred layer B from 1.5 ± 0.3 mm to 2.6 ± 0.3 mm depth which comprising bundles of C. chthonoplastes and filaments of CLB; V: layer from 2.6 ± 0.3 mm to 4 ± 0.3 mm depth corresponded to a transition zone where large amounts of mineral particles sand grains and biogenic calcite occurred intertwined with of C. chthonoplastes and filaments of CLB; VI: layer comprising black coloured sediment ranging from 4 ± 0.3 mm to 6 ± 0.5 mm depth.
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pone.0130552.g001: Virus observed in different depth layers (see below) and different fractions of the microbial mat dominated by diatoms, Coleofasciculus chthonoplastes, and Chloroflexus-like bacteria (CLB), sampled in March 2007.Left panel (A): Virus counts in the extracted water fraction (pore water and water soaked into the extracellular polymer matrix). Right panel (B): Virus attached to solid organic and mineral matter. (circles = without acidification, squares = after 10 min of acidification, see Methods). Description of the different layers: I: the top layer from 0 to 0.8 ± 0.2 mm depth, comprised dense populations of diatoms of the genera: Frustula, Cymbella, Denticula, Nitzschia and few bundles of C. chthonoplastes and filaments of CLB; II: layer from 0.8 ± 0.2 mm to 1.5 ± 0.2 mm depth that separated very well from the top layer and comprised lesser densities of diatoms with high quantities biogenic high-Mg calcite grains (cf. Fig 3); III: locally a very fine layer was observed at 1.5 ± 0.3 mm depth that was particularly enriched in biogenic high-Mg calcite embedded in an organic matrix; IV: A layer located below the high densities of biogenic calcium carbonate crystals occurred layer B from 1.5 ± 0.3 mm to 2.6 ± 0.3 mm depth which comprising bundles of C. chthonoplastes and filaments of CLB; V: layer from 2.6 ± 0.3 mm to 4 ± 0.3 mm depth corresponded to a transition zone where large amounts of mineral particles sand grains and biogenic calcite occurred intertwined with of C. chthonoplastes and filaments of CLB; VI: layer comprising black coloured sediment ranging from 4 ± 0.3 mm to 6 ± 0.5 mm depth.

Mentions: The mat sampled in March 2007 corresponded to a very young microbial mat (less than two years, see Methods). Fig 1 describes depth profiles of viruses in the mat and the legend describes the composition of the different layers based on morphological light microscopy observations. The concentrations of the viruses suspended in extracted water fraction ranged between 2 and 10 × 109 viruses per mL and the values for the different layers are depicted in Fig 1A. Using these samples for testing the effect of the acidification procedure (10 min in 0.1 M HCl, see Methods), it was found that this treatment induced losses of on average 60% of free viruses (N = 10). Fig 1B shows the concentrations of viruses attached to the solid organic matter and mineral particles, which ranged from 2 to 9.5 × 109 per g dry weight observed in layers III and IV, respectively. This figure also shows the concentrations found after the 10 min acidification treatment. In the layers I and IV, which were dominated by diatom populations and by communities of C. chthonoplastes associated with CLB, respectively, the number of viruses was 40% lower than in the non-acidified control. This can be explained to a large extent by losses induced by acidification. In contrast, the layers II, III, V and VI showed significantly higher viruses numbers after acidification, which shows that viruses were liberated by dissolution of the (Ca,Mg)CO3 grains. The layers II and III, which were particularly rich in biogenic (Ca,Mg)CO3 grains, showed a 4.5 and 3.3 fold increase upon acidification. This indicates that a large part of the viruses associated with organic and mineral solids was actually included in the biogenic (Ca,Mg)CO3 grains.


Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats.

De Wit R, Gautret P, Bettarel Y, Roques C, Marlière C, Ramonda M, Nguyen Thanh T, Tran Quang H, Bouvier T - PLoS ONE (2015)

Virus observed in different depth layers (see below) and different fractions of the microbial mat dominated by diatoms, Coleofasciculus chthonoplastes, and Chloroflexus-like bacteria (CLB), sampled in March 2007.Left panel (A): Virus counts in the extracted water fraction (pore water and water soaked into the extracellular polymer matrix). Right panel (B): Virus attached to solid organic and mineral matter. (circles = without acidification, squares = after 10 min of acidification, see Methods). Description of the different layers: I: the top layer from 0 to 0.8 ± 0.2 mm depth, comprised dense populations of diatoms of the genera: Frustula, Cymbella, Denticula, Nitzschia and few bundles of C. chthonoplastes and filaments of CLB; II: layer from 0.8 ± 0.2 mm to 1.5 ± 0.2 mm depth that separated very well from the top layer and comprised lesser densities of diatoms with high quantities biogenic high-Mg calcite grains (cf. Fig 3); III: locally a very fine layer was observed at 1.5 ± 0.3 mm depth that was particularly enriched in biogenic high-Mg calcite embedded in an organic matrix; IV: A layer located below the high densities of biogenic calcium carbonate crystals occurred layer B from 1.5 ± 0.3 mm to 2.6 ± 0.3 mm depth which comprising bundles of C. chthonoplastes and filaments of CLB; V: layer from 2.6 ± 0.3 mm to 4 ± 0.3 mm depth corresponded to a transition zone where large amounts of mineral particles sand grains and biogenic calcite occurred intertwined with of C. chthonoplastes and filaments of CLB; VI: layer comprising black coloured sediment ranging from 4 ± 0.3 mm to 6 ± 0.5 mm depth.
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pone.0130552.g001: Virus observed in different depth layers (see below) and different fractions of the microbial mat dominated by diatoms, Coleofasciculus chthonoplastes, and Chloroflexus-like bacteria (CLB), sampled in March 2007.Left panel (A): Virus counts in the extracted water fraction (pore water and water soaked into the extracellular polymer matrix). Right panel (B): Virus attached to solid organic and mineral matter. (circles = without acidification, squares = after 10 min of acidification, see Methods). Description of the different layers: I: the top layer from 0 to 0.8 ± 0.2 mm depth, comprised dense populations of diatoms of the genera: Frustula, Cymbella, Denticula, Nitzschia and few bundles of C. chthonoplastes and filaments of CLB; II: layer from 0.8 ± 0.2 mm to 1.5 ± 0.2 mm depth that separated very well from the top layer and comprised lesser densities of diatoms with high quantities biogenic high-Mg calcite grains (cf. Fig 3); III: locally a very fine layer was observed at 1.5 ± 0.3 mm depth that was particularly enriched in biogenic high-Mg calcite embedded in an organic matrix; IV: A layer located below the high densities of biogenic calcium carbonate crystals occurred layer B from 1.5 ± 0.3 mm to 2.6 ± 0.3 mm depth which comprising bundles of C. chthonoplastes and filaments of CLB; V: layer from 2.6 ± 0.3 mm to 4 ± 0.3 mm depth corresponded to a transition zone where large amounts of mineral particles sand grains and biogenic calcite occurred intertwined with of C. chthonoplastes and filaments of CLB; VI: layer comprising black coloured sediment ranging from 4 ± 0.3 mm to 6 ± 0.5 mm depth.
Mentions: The mat sampled in March 2007 corresponded to a very young microbial mat (less than two years, see Methods). Fig 1 describes depth profiles of viruses in the mat and the legend describes the composition of the different layers based on morphological light microscopy observations. The concentrations of the viruses suspended in extracted water fraction ranged between 2 and 10 × 109 viruses per mL and the values for the different layers are depicted in Fig 1A. Using these samples for testing the effect of the acidification procedure (10 min in 0.1 M HCl, see Methods), it was found that this treatment induced losses of on average 60% of free viruses (N = 10). Fig 1B shows the concentrations of viruses attached to the solid organic matter and mineral particles, which ranged from 2 to 9.5 × 109 per g dry weight observed in layers III and IV, respectively. This figure also shows the concentrations found after the 10 min acidification treatment. In the layers I and IV, which were dominated by diatom populations and by communities of C. chthonoplastes associated with CLB, respectively, the number of viruses was 40% lower than in the non-acidified control. This can be explained to a large extent by losses induced by acidification. In contrast, the layers II, III, V and VI showed significantly higher viruses numbers after acidification, which shows that viruses were liberated by dissolution of the (Ca,Mg)CO3 grains. The layers II and III, which were particularly rich in biogenic (Ca,Mg)CO3 grains, showed a 4.5 and 3.3 fold increase upon acidification. This indicates that a large part of the viruses associated with organic and mineral solids was actually included in the biogenic (Ca,Mg)CO3 grains.

Bottom Line: Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses.Nucleic acid staining revealed that they contain DNA or RNA.In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 10(9) viruses per g of calcite.

View Article: PubMed Central - PubMed

Affiliation: Centre for Marine Biodiversity, Exploitation and Conservation (MARBEC),Université de Montpellier, CNRS, IRD, Ifremer, Place Eugène Bataillon, Case 093, 34095, Montpellier, France.

ABSTRACT
Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake "La Salada de Chiprana", Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>10(10) viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 10(9) viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as "nanobacteria" and that viruses may play a role in initiating calcification.

No MeSH data available.


Related in: MedlinePlus