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Low-cost cultivation and sporulation of alkaliphilic Bacillus sp. strain AK13 for self-healing concrete.
Hong, Minyoung; Kim, Wonjae; Park, Woojun.
Afiliación
  • Hong M; Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
  • Kim W; Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
  • Park W; Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
J Microbiol Biotechnol ; 29(12): 1982-1992, 2019 Dec 28.
Article en En | MEDLINE | ID: mdl-31650771
ABSTRACT
The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 108 and 1.25 ± 0.12 × 108 CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 109 CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.40.4 ratio compared to 0.40.25 (the original ratio of the B4 medium) and 0.40.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 106 CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bacillus / Carbonato de Calcio / Técnicas de Cultivo de Célula / Medios de Cultivo Tipo de estudio: Health_economic_evaluation / Prognostic_studies Idioma: En Revista: J Microbiol Biotechnol Año: 2019 Tipo del documento: Article

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bacillus / Carbonato de Calcio / Técnicas de Cultivo de Célula / Medios de Cultivo Tipo de estudio: Health_economic_evaluation / Prognostic_studies Idioma: En Revista: J Microbiol Biotechnol Año: 2019 Tipo del documento: Article
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