Steering microbial activity by tailor-made media composition for stone conservation

The presence of water and its flow in the porous network of stone masonry are major drivers of weathering development. In this study we expect that the manipulation of the pore scale conditions of the stone material can reduce weathering and improve durability. Here, we focus on the potential of microorganisms for stone conservation through tailor-made media composition. Microorganisms attach to rock surfaces and can live inside pore systems. Their presence and metabolites might influence the stone’s durability in a positive way. Through bacterial phenomena such as bioclogging, biocement, and biogas production, the pore scale environment could be altered and thereby influencing the water flow. In this study, a bacterial denitrification metabolism will be engineered for creating these three phenomena. Here, we will present a quantitative model to predict the extent of nitrogen gas production, bacterial growth, and carbonate precipitation based on media composition. The model will be parameterized and validated based on batch experiments. The results of the model will be used to identify optimal media compositions to induce the desired processes to a desired extent inside the stone network. Hence, the model will create the basis to investigate in the future the consequences of microbially mediated reactions in the rock on water flow and, ultimately, stone conservation.