What is it about?
Bacterially induced calcium carbonate precipitation of a Cupriavidus metallidurans isolate was investigated to develop an environmentally friendly method for restoration and preservation of ornamental stones. Biomineralization performance was carried out in a selected growth medium via a Design of Experiments (DoE) approach using, as design factors, the temperature, growth medium concentration, and inoculum concentration. The optimum conditions were determined with the aid of consecutive experiments based on response surface methodology (RSM) and were successfully validated thereafter. Analytical methods provided an insight to the biomineral characteristics. Sonication tests proved the efficiency and consolidating effect of vaterite deposition. At the final stage of implementation, the bacteria were sprayed onto a marble surface under non-sterile conditions to study its bioconsolidation effects. Our isolate could create a solid novel layer of vaterite on marble substrate withstanding sonication forces. Statistical analysis can be utilized as a tool for screening bacterial bio-precipitation as it considerably reduces the experimental time and effort needed for bacterial evaluation. DoE assisted in predicting the optimum conditions for biomineral formation while spraying minimum amount of inoculated media on marble substrate, which showed that sufficient biomineralization may occur under conditions close to an in situ application.
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Why is it important?
Our strain Cupriavidus metallidurans has been deposited in a publicly accessible belonging to the Greek collection of bacteria of Agricultural University of Athens culture collection - Laboratory of Dairy Research and has taken the collection number ACA-DC 4073. To the best of our knowledge, this is the first study considering a C. metallidurans isolate and its prospects in stone conservation. Vaterite’s stability under different nutrient and temperature conditions was demonstrated; a notion that has gradually become more apparent in recent research. Our results showed that it was stable under the interaction with cell membranes during high metabolic activity.
Perspectives
Color differentiations, and comparison with ancient marble samples, stress that further investigation could be conducted to obtain results that balances adequate biomineralization and the least adverse aesthetic effects that shall satisfy restoration intervention. C. metallidurans ACA-DC 4073 could be considered as a candidate for future interventions or exploited if detected among stone microflora.
Professor Fotis Rigas
National Technical University of Athens
Read the Original
This page is a summary of: Cupriavidus metallidurans biomineralization ability and its application as a bioconsolidation enhancer for ornamental marble stone, Applied Microbiology and Biotechnology, April 2014, Springer Science + Business Media,
DOI: 10.1007/s00253-014-5753-0.
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