Currently, Lagoa Vermelha has a depth of 1.0 m, with a small central core reaching a depth of 1.4 m, while Hohn et al. (1986) described a water column up to 1.70 m. In the present study, there was a greater tendency of accumulation of fine material, with little concentration of carbonates, at the highest depths. As expected, the accumulation of fine sediment was also associated with higher concentrations of organic matter. The results obtained in the bathymetric survey showed occurrence of a sedimentation process in this lagoon. Some physico-chemical parameters of the water column were determined by Hohn et al. (1986) during the years 1982 to 1984. At that time, dissolved oxygen saturation (102 to 125%) and pH (8.47 to 9.37) were higher than
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Thus, the comparison was made with samples from the water column of the nearest lagoon system (Guerra et al, 2011), whose mean was 106 cells.mL-1, three orders lower than the values found at Lagoa Vermelha. The high number of bacterial cells have ensure an efficient process of mineralization of the primary production in the water column connected to the eutrophic condition of Lagoa Vermelha. In the water-sediment interface of Lagoa Vermelha, the halovirus morphotypes are icosahedral with contractile tails of medium length (myovirus) or short non-contractile tails (sifovirus and podovirus), with predominance of the Myoviridae family (42%). They are represented by both archaeal and bacterial haloviruses (Atanasova et al 2015). In the microbial mats of the Lagoa Vermelha, 64% of the VLPs belonged to the Caudovirales family with the following distribution: Siphoviridae (50%), Myoviridae (35%) and Podoviridae (15%) as was also described by Pacton et al. …show more content…
The bacterial sulfate-reduction accounts for more than 80% of carbon oxidation (Canfield et al 1993) and can mediate microbial mineralization of dolomite under physiological temperatures and anoxic conditions (Warthmann et al 2000; van Lith et al 2003a,b; Warthmann et al 2005). Mineral precipitation may be a by-product of bacterial metabolism and the quality and quantity of exopolymeric substances (EPS) control the mineralogy and morphology of crystalline phases (Arp et al 2003; Braissant et al 2003, 2007; Tourney and Ngwenya 2009), resulting in the laminated structures produced by successive deposition of layers of microbial mats (Burne & Moore, 1987; Riding, 2000). The crust in both Highborne Cay stromatolites and hypersaline saltpan mats coincides with the location of maximum sulfate reduction and sulfate-reducing bacteria (Visscher et al., 2000). In the present study, microbial mat at Lagoa Vermelha still producing biominerals, mainly at the sulfate-reducing layer, even under the actual eutrophic conditions. The eutrophic condition is related to urbanization with inadequate land use, since the region of the hypersaline lagoons has approximately 124,940 inhabitants (IBGE 2016). These conditions intensify the introduction of several classes of organic and inorganic compounds that support
Thus, the comparison was made with samples from the water column of the nearest lagoon system (Guerra et al, 2011), whose mean was 106 cells.mL-1, three orders lower than the values found at Lagoa Vermelha. The high number of bacterial cells have ensure an efficient process of mineralization of the primary production in the water column connected to the eutrophic condition of Lagoa Vermelha. In the water-sediment interface of Lagoa Vermelha, the halovirus morphotypes are icosahedral with contractile tails of medium length (myovirus) or short non-contractile tails (sifovirus and podovirus), with predominance of the Myoviridae family (42%). They are represented by both archaeal and bacterial haloviruses (Atanasova et al 2015). In the microbial mats of the Lagoa Vermelha, 64% of the VLPs belonged to the Caudovirales family with the following distribution: Siphoviridae (50%), Myoviridae (35%) and Podoviridae (15%) as was also described by Pacton et al. …show more content…
The bacterial sulfate-reduction accounts for more than 80% of carbon oxidation (Canfield et al 1993) and can mediate microbial mineralization of dolomite under physiological temperatures and anoxic conditions (Warthmann et al 2000; van Lith et al 2003a,b; Warthmann et al 2005). Mineral precipitation may be a by-product of bacterial metabolism and the quality and quantity of exopolymeric substances (EPS) control the mineralogy and morphology of crystalline phases (Arp et al 2003; Braissant et al 2003, 2007; Tourney and Ngwenya 2009), resulting in the laminated structures produced by successive deposition of layers of microbial mats (Burne & Moore, 1987; Riding, 2000). The crust in both Highborne Cay stromatolites and hypersaline saltpan mats coincides with the location of maximum sulfate reduction and sulfate-reducing bacteria (Visscher et al., 2000). In the present study, microbial mat at Lagoa Vermelha still producing biominerals, mainly at the sulfate-reducing layer, even under the actual eutrophic conditions. The eutrophic condition is related to urbanization with inadequate land use, since the region of the hypersaline lagoons has approximately 124,940 inhabitants (IBGE 2016). These conditions intensify the introduction of several classes of organic and inorganic compounds that support