Calcium Carbonate Mineralization: Involvement of Extracellular Polymeric Materials Isolated from Calcifying Bacteria

Department of Basic and Applied Biology, University of L'Aquila, 67010 L'Aquila, Italy.
Microscopy and Microanalysis (Impact Factor: 1.88). 06/2012; 18(4):829-39. DOI: 10.1017/S1431927612000426
Source: PubMed


This study highlights the role of specific outer bacterial structures, such as the glycocalix, in calcium carbonate crystallization in vitro. We describe the formation of calcite crystals by extracellular polymeric materials, such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) isolated from Bacillus firmus and Nocardia calcarea. Organic matrices were isolated from calcifying bacteria grown on synthetic medium--in the presence or absence of calcium ions--and their effect on calcite precipitation was assessed. Scanning electron microscopy observations and energy dispersive X-ray spectrometry analysis showed that CPS and EPS fractions were involved in calcium carbonate precipitation, not only serving as nucleation sites but also through a direct role in crystal formation. The utilization of different synthetic media, with and without addition of calcium ions, influenced the biofilm production and protein profile of extracellular polymeric materials. Proteins of CPS fractions with a molecular mass between 25 and 70 kDa were overexpressed when calcium ions were present in the medium. This higher level of protein synthesis could be related to the active process of bioprecipitation.

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Available from: Claudia Ercole, Jan 03, 2015
    • "Concerning CaCO 3 -precipitating bacteria and stone environments, to the authors' knowledge only one study has reported the effect of calcium on EPS production. In this study, the presence of 4 mM calcium ions in the culture medium increased biofilm formation by strains of Bacillus firmus and Nocardia calcarea isolated from an Italian karst cave (Ercole et al. 2012). The amounts of EPS and capsular polysaccharides (CPS) extracted from these strains were higher in the presence of calcium. "
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    ABSTRACT: Heterotrophic CaCO3-precipitating bacteria were isolated from biofilms on deteriorated ignimbrites, siliceous acidic rocks, from Morelia Cathedral (Mexico) and identified as Enterobacter cancerogenus (22e), Bacillus sp. (32a) and Bacillus subtilis (52g). In solid medium, 22e and 32a precipitated calcite and vaterite while 52g produced calcite. Urease activity was detected in these isolates and CaCO3 precipitation increased in the presence of urea in the liquid medium. In the presence of calcium, EPS production decreased in 22e and 32a and increased in 52g. Under laboratory conditions, ignimbrite colonization by these isolates only occurred in the presence of calcium and no CaCO3 was precipitated. Calcium may therefore be important for biofilm formation on stones. The importance of the type of stone, here a siliceous stone, on biological colonization is emphasized. This calcium effect has not been reported on calcareous materials. The importance of the effect of calcium on EPS production and biofilm formation is discussed in relation to other applications of CaCO3 precipitation by bacteria.
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    • "Broadly speaking, differences in crystal morphology occur because of the presence and different concentrations of xanthan and amino acids. Experiments have also shown a direct relationship between cell growth and the presence of capsular polysaccharides (which compose a structural component of biofilms) [35] which may also help explain the structural network patterns found in our B. pasteurii sample. One of the reasons for this effect is likely to be that complex molecules found in the EPS bind to the surface of the crystal, either prompting or inhibiting crystal formation across specific faces of the crystal over specific times. "
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    ABSTRACT: This paper discusses the role that material ecologies might have in the emerging engineering paradigm of Synthetic Biology (hereafter SB). In this paper we suggest that, as a result of the paradigm of SB, a new way of considering the relationship between computation and material forms is needed, where computation is embedded into the material elements themselves through genetic programming. The paper discusses current trends to conceptualize SB in traditional engineering terms and contrast this from design speculations in terms of bottom up processes of emergence and self organization. The paper suggests that, to reconcile these positions, it is necessary to think about the design of new material systems derived from engineering living organisms in terms of a state space of production. The paper analyses this state space using the example of biomineralization, with illustrations from simple experiments on bacteria induced calcium carbonate. The paper suggests a framework involving three interconnected state spaces defined as: cellular (the control of structures within the cell structures within a cell, and specifically DNA and its expression through the process of transcription and translation); chemical (considered to occur outside the cell, but in direct chemical interaction with the interior of the cell itself); physical (which constitutes the physical forces and energy within the environment). We also illustrate, in broad terms, how such spaces are interconnected. Finally the paper will conclude by suggesting how a material ecologies approach might feature in the future development of SB.
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    • "The biofilm structure seems to be largely determined by the production of slime like matrix of EPS, which provides structural support for the biofilm. Ercole et al. 2012 also reported that deposition of carbonate crystals is promoted by EPS. "
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