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KMID : 0613820150250020237
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Journal of Life Science
2015 Volume.25 No. 2 p.237 ~ p.242
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Assessment of Bio-corrosive Effect and Determination of Controlling Targets among Microflora for Application of Multi-functional CFB on Cement Structure
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Park Jong-Myong
Park Sung-Jin
Kim Sa-Youl
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Abstract
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The use of calcite-forming bacteria (CFB) in crack remediation and durability improvements in construction materials creates a permanent and environmentally-friendly material. Therefore, research into this type of application is stimulating interdisciplinary studies between microbiology and architectural engineering. However, the mechanisms giving rise to these materials are dependent on calcite precipitation by the metabolism of the CFB, which raises concerns about possible hazards to cement-based construction due to microbial metabolic acid production. The aim of this study was to determine target microorganisms that possibly can have bio-corrosive effects on cement mortar and to assess multi-functional CFBs for their safe application to cement structures. The chalky test was first used to evaluate the CaCO3 solubilization feature of construction sites by fungi, yeast, bacterial strains. Not all bacterial strains are able to solubilize CaCO3, but C. sphaerospermum KNUC253 or P. prolifica KNUC263 showed CaCO3 solubilization activity. Therefore, these two strains were identified as target microorganisms that require control in cement structures. The registered patented strains Bacillus aryabhatti KNUC205, Arthrobacter nicotianae KNUC2100, B. thuringiensis KNUC2103 and Stenotrophomonas maltophilia KNUC2106, reported as multifunctional CFB (fungal growth inhibition, crack remediation, and water permeability reduction of cement surfaces) and isolated from Dokdo or construction site were unable to solubilize CaCO3. Notably, B. aryabhatti KNUC205 and A. nicotianae KNUC2100 could not hydrolyze cellulose or protein, which can be the major constituent macromolecules of internal materials for buildings. These results show that several reported multi-functional CFB can be applied to cement structures or diverse building environments without corrosive or bio-deteriorative risks.
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KEYWORD
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Bio-deterioration, CaCO3 solubilization, cement mortar, calcite-forming bacteria (CFB), microbially induced CaCO3 precipitation (MICP)
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