Unraveling the microbiomes contributing to biodeterioration dynamics of limestone heritage at the Longmen Grottoes archeological site.

backgroundThe Longmen Grottoes archeological site is a representative of the UNESCO World Heritage. Unfortunately, the long-term exposure to the outdoor environment has caused severe damage to the limestone heritage at this archeological site due to microbial colonization and biodeterioration. However, a lack of understanding of the microbiomes and mechanisms involved in biodeterioration processes has largely restricted the development of sustainable conservation of the heritage there.

resultsHere, we systematically compared physicochemical characteristics between the low and high biodeterioration caves, identified the keystone microbial communities and functions that shape the biodeterioration dynamics, and explored the biogeochemical cycles of carbon, nitrogen, and sulfur that drive the biodeterioration divergence. As a result, physicochemical parameters of the bio-deteriorated rocks of the caves suggest a substantial divergence of biodeterioration. Microbial community structures and functions revealed that the metabolic potential of carbon fixation, nitrification, and denitrification processes shape the biodeterioration dynamics. The results strongly suggest that nitrification is a major contributor to the observed biodeterioration divergence.

conclusionsWe revealed that cyanobacteria, as the main organic carbon producer, support the development of microbiomes that drive the biogeochemical cycles of carbon, nitrogen, and sulfur. Importantly, corrosion of minerals by microbial acids through ammonia oxidation and nitrification is the main consequence of the biodeterioration dynamics. Our findings will provide a basis for sustainable conservation of outdoor stone heritage from microbially induced biodeterioration. Video Abstract.