Diversity of cyanobacteria on stone monuments and building facades of India and their phylogenetic analysis

• Biofilms occurring on Indian monuments mainly composed of cyanobacteria.
• They principally belong to the genera under Nostocales and Stigonematales.
• Cyanobacteria from Indian monuments formed a genera-wise monophyletic clade.
• Cyanobacteria from India clustered differently with those from temperate regions.

Many archaeologically important stone temples, caves, mortar monuments with artistic expression as well as building facades of India are now disfigured due to colonization of cyanobacterial biofilms leading to weathering of the substratum. They are composed of species principally belonging to the genera Hassallia, Tolypothrix, Scytonema, Lyngbya and Calothrix, which appeared soon after wetting of the biofilms. Several other species of genera Aulosira, Nostoc, Camptylonema, Dichothrix, Chlorogloeopsis and Westiellopsis occurred as associated organisms as they appeared upon prolonged culture of the biofilms. Molecular phylogenetic analysis based on 16S rRNA partial gene sequencing of all these 24 cyanobacteria species under 11 genera isolated from the surfaces of monuments and building facades of India along with those of other species isolated from stone surfaces in subaerial habitats and hypogeal environments in different regions of the globe showed that those species from tropical regions were clustered together, quite different from cyanobacteria of the genera Chroococcidiopsis, Leptolyngbya, Phormidium, Nostoc, Rexia, Symphyonemopsis, Scytonema, Tolypothrix and Calothrix occurring in the temperate regions.