Geetanjali Geet -- I have not worked with stone deterioration, but I will try to give you some possible ideas. First, it would help if you could give a little insight into the type of stone you want to study - natural rocks, statues, buildings, cave insides..... Is the stone porous? I have worked a bit with bacteria in sand, so maybe looking at the bacterial community in porous stone could help. Otherwise I recommend sampling the microbiome from the stone. Culture as many types of the bacteria as possible. Find the acids and other metabolites. Which ones can degrade the stone? Do they do better in combination? Do the metabolites from several of the different species in the microbiome do more degradation? Hope this gives you some ideas.