An exploratory study on crack healing in cementitious matrices induced by Pythium aphanidermatum

The biomineralization of calcium carbonate (CaCO₃) mediated by microorganisms has been extensively studied for decades, with a predominant focus on bacteria, algae, and fungi. However, the functional and operational limitations of these species highlight the need to investigate new biological agents. This study aims to evaluate the biomineralization potential of Pythium aphanidermatum, an oomycete from the Chromista kingdom, for crack-healing applications in cement mortars. Its ureolytic capacity to accelerate CaCO₃ formation was analyzed, and liquid cultures with controlled concentrations of cells and calcium acetate were designed. Additionally, the microorganism's growth in alkaline media was evaluated. A surface application technique was adapted to determine the crack repair potential in cementitious matrices. Results demonstrated that P aphanidermatum does not necessarily require urea to form CaCO₃. A concentration of 10⁵ cells/mL and 100 mM of calcium acetate were optimal for microorganism development through surface application and CaCO₃ formation. It was also observed that P. aphanidermatum can tolerate alkaline environments (pH 11). Finally, its filamentous growth allowed partial filling of cracks in carbonated cement mortars. This work expands the scope of biomineralization by incorporating an organism from a previously unreported kingdom into this field, laying the foundation for sustainable and innovative applications in the construction industry.