Bacterial calcium carbonate formation and its application for self-healing concrete

다국어 초록 (Multilingual Abstract)

Microbially induced calcium carbonate precipitation (MICP) has been widely explored and applied in the fields of Microbiology and Environmental Engineering over the last decade. CaCO3 is naturally precipitated as a byproduct of various microbial metabolic activities under the presence of calcium, while biological function of Ca2+ among prokaryotes is far from clear. Physiology and ecology of CaCO3 precipitating (CCP) bacteria are also poorly illuminated given the fact that they prevail in environment. MICP has been extensively examined for applications in self-healing concrete. Biogenic crack repair helps mitigate the high maintenance costs of concrete in an eco-friendly manner. In this paper, metabolic pathways that result in conditions favorable for CaCO3 precipitation, current and potential applications in concrete, and the remaining biological challenges are reviewed. Moreover, a novel CCP bacterium Lysinibacillus boronitolerans YS11 that induced an alkaline environment by non-ureolytic mechanism is characterized. Then, coculture between strain YS11 and alkaliphilic Bacillus sp. AK13 was conducted to unravel interspecies interaction of alkali generating CCP bacteria. Alkalization by YS11 facilitated the growth of AK13, which enabled co-occurrence of two species. Enhanced Biofilm and attached CaCO3 formation in coculture was observed using confocal laser scanning microscopy. CaCO3 analyzed by field emission scanning electron microscopy showed compact morphology in coculture compared to YS11 alone. Finally, using L. boronitolerans YS11 as a model species for CCP bacteria, whole genome sequencing and transcriptomics in Ca2+ poor and rich conditions were conducted as to understand genetic characteristic and differential gene expressions during CaCO3 precipitation. Genes involved in branched chain amino acid and branched chain fatty acid syntheses were highly upregulated with multi-drug efflux pump and membrane protein related genes when in provided with Ca2, suggesting modification in membrane during Ca2+ contact. Various phenotypes; growth, biofilm formation, sporulation, swimming motility, and stress response, were altered under Ca2+ provision. The results provide comprehensive insight into CCP bacteria; from its molecular physiology and ecology to application in self-healing concrete.

목차 (Table of Contents)

• Abstract i
• Abstract in Korean iv
• Acknowledgment vi
• Author’s Information viii
• Index x
• List of Tables xiii
• List of Figures xiv
• Chapter 1. General Introduction: Current challenges and future directions for bacterial self-healing concrete 1
• 1.1. Abstract 2
• 1.2. Introduction 4
• 1.3. Microbially induced calcium carbonate precipitation 11
• 1.4. Applications of calcium carbonate-precipitating bacteria in concrete 18
• 1.5. Limitations 39
• 1.6. Concluding remarks 47
• 1.7. References 49
• Chapter 2. Non-ureolytic calcium carbonate precipitation by Lysinibacillus sp. YS11 isolated from the rhizosphere of Miscanthus sacchariflorus 63
• 2.1. Abstract 64
• 2.2. Introduction 66
• 2.3. Materials and Methods 69
• 2.4. Results 76
• 2.5. Discussion 96
• 2.6. References 101
• Chapter 3. Dual species calcium carbonate-biofilm formation by alkali generating Lysinibacillus boronitolerans YS11 and alkaliphilic Bacillus sp. AK13 109
• 3.1. Abstract 110
• 3.2. Introduction 112
• 3.3. Materials and Methods 117
• 3.4. Results 124
• 3.5. Discussion 154
• 3.6. References 157
• Chapter 4. Transcriptional and phenotypic responses to calcium in CaCO3 precipitating Lysinibacillus boronitolerans YS11 165
• 4.1. Abstract 166
• 4.2. Introduction 167
• 4.3. Materials and Methods 169
• 4.4. Results and Discussion 171
• 4.5. References 200