Lithophytic Cyanobacteria on Indian Stone Temples and Monuments

India is rich in lithic (stone-built) temples and monuments which epitomize our rich cultural heritage and contribute significantly to the tourism and economy of the country. The light-exposed surfaces of temples and monuments are readily colonized and inhabited by various species, belonging to different genera, of lithophytic (lithobiontic) cyanobacteria (blue-green algae). Lithophytic cyanobacteria possess remarkable adaptability and tolerance to various abiotic stresses, such as desiccation, high light intensity, high levels of solar UV radiation and high temperature which they often encounter on exposed rock surfaces and external walls of lithic temples, monuments and buildings. They are primary colonizers of nutrient-poor lithic substrata. Lithophytic cyanobacteria can grow both as epiliths and endoliths. They comprise major component of sub-aerial biofilms or crusts on exposed surfaces.The colonization and growth of lithophytic cyanobacteria can affect stone-built temples, monuments and buildings directly or indirectly in various ways, ultimately resulting in their biodeterioration that is manifested as both aesthetic and structural damage. Biodeterioration of stone-built monuments and buildings is a serious problem globally. The article provides an overview of the occurrence and diversity of lithophytic cyanobacteria on Indian stone-built temples and monuments and their potential effects.