The Significant Role of Different Magnesium: Carbonate Minerals Induced by Moderate Halophile <em>Staphylococcus epidermis</em> Y2

Abstract

Carbonate precipitation induced by microorganism has become a hot spot in the field of carbonate sedimentology, while the effect of different magnesium on biominerals has rarely been studied. Therefore, magnesium sulfate and magnesium chloride were used to investigate the significant role played on carbonate minerals. In this study, Staphylococcus epidermidis Y2 was isolated and identified by 16S rDNA homology comparison. The ammonia, pH, carbonic anhydrase, carbonate and bicarbonate ions were investigated. The mineral phase, morphology and elemental composition were analyzed by XRD and SEM-EDS. The ultrathin slices of bacteria were analyzed by HRTEM-SAED and STEM. The result showed that this bacterium could release ammonia and carbonic anhydrase to increase pH, and elevate the supersaturation via a large number of carbonate and bicarbonate ions released through carbon dioxide hydration catalyzed by carbonic anhydrase. The crystal cell density of monohydrocalcite was lower in magnesium chloride medium than that in magnesium sulfate medium. The crystal grew in a mode of spiral staircas in magnesium sulfate medium, while in a concentric circular pattern in magnesium chloride medium. There was no obvious intracellular biomineralization. This study may be helpful to further understand the biomineralization mechanism, may also provide some references for the reconstruction of paleogeological environment.

Heavy metals bioremediation and water softening using ureolytic strains Metschnikowia pulcherrima and Raoultella planticola

“…As observed from EDX profiles, strong signal peaks with considerable percentage of carbon, oxygen and calcium were detected at 0.277, 0.525 and 3.69 keV, respectively. Notably, Na and Cl peaks were also detected as small signals, suggesting them to be residuals from media ingredients incorporated in precipitated crystals during the ureolysis process as reported by Han et al 34 In addition, P and S peaks were observed at 2.013 and 2.3 keV, respectively, implying the biological origin of CaCO 3 crystals, both elements being building blocks of vital biomolecules such as proteins, nucleic acids, phospholipids and polysaccharides. 35,36 As suggested by Ghosh et al, 37 such elements could donate stabilization for biosynthesized precipitates.…”

Heavy Metals Bioremediation and Water Softening Using Ureolytic Metschnikowia Pulcherrima and Raoultella Planticola Strains

“…Notably, Na and Cl peaks were also detected in a small percentage, suggesting to be residuals from media ingredients that incorporated in precipitated crystals during ureolysis process as reported by Han et al, (2018). In addition, P and S peaks were observed at emission peaks 2.013 and 2.3 keV, correspondingly, implying the biological origin of CaCO3 crystals.…”