| Congresso Brasileiro de Microbiologia 2023 | Resumo: 128-1 | ||||
Resumo:Reinforced concrete structures often face durability challenges due to harsh weather conditions and ongoing human activities, resulting in crack formation and reduced lifespan. To overcome these issues, several technologies have emerged, focusing on self-healing properties in cement-based materials. One notable advancement involves the utilization of bacteria to facilitate microbiologically induced calcium carbonate precipitation (MICP). Incorporating bacteria within the cementitious matrix, along with essential nutrients, is crucial for promoting the healing process. However, this is particularly challenging due to the matrix's alcaline pH and the salinity of marine structures like oil platforms. This study aimed to prospect marine bacteria with potential applications in bioconcrete. Bacteria isolated from the São Pedro and São Paulo archipelago, as part of a parallel research project conducted by our research group, were assessed for their halotolerance and alkalitolerance. The experiment encompassed a total of eight distinct conditions in LB medium, including three variations of alkalinity (pH 8, pH 9, and pH 10) and four levels of salinity (2%, 4%, 8%, and 12% NaCl), with the control being only LB medium. The resistance of the bacteria under these conditions was determined by quantifying the colony forming units (CFUs) at specific time points: 15, 24, 48, 72, and 120 hours. The CFU counts were performed in triplicate by drop plate method, with an OD600 set to 0.1. Additionally, their genomes were analyzed via KofamKOALA in Kegg Pathways to identify metabolic pathways associated with established bioconcrete nutrient sources. Out of the 22 tested bacteria, 50% exhibited maximum resistance either to alkalinity or salinity. Intriguingly, the commonly used standard bacteria Bacillus subtilis and Sporosarcina pasteurii displayed comparably lower resistance levels. The genomes of the top 10 most resistant bacteria were analyzed to identify metabolic pathways involved in the metabolization of Nitrogen, Starch, and Lactate. Through a comprehensive evaluation of stress resistance tests and metabolic pathways of each bacterium, the three most promising candidates were identified: Vibrio diabolicus, Brachybacterium avium, and Stutzerimonas frequens.
Palavras-chave: bioconcrete, marine bacteria screening, halotolerance, alkalitolerance, metabolic repertoire Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Pesquisa e Desenvolvimento (CNPq) | |||||