Stone Metagenome Raw sequence reads
Rock art paintings represent fragile ecosystems that support complex microbial communities tuned to both the lithic substrate and climatic conditions. The composition and activity of these microbial communities associated with different weathering patterns affecting rock art sites remain unexplored. This work aimed to investigate how bacterial community ecological strategies differ based on the levels of weathering observed in stone walls that host prehistoric paintings. To investigate the link between weathering patterns and stone microbiome, SEM-EDS investigations coupled with 16S rRNA gene sequencing and PiCRUST analysis were applied on different weathered surfaces that affect African rock paintings. Metabolic pathways involved in carbon fixation, biogeochemical N, S, and P cycles, stress resistance, and various weathering processes such as metal uptake/regulation, siderophore biosynthesis, calcite precipitation, and oxalate degradation were predicted. The study demonstrated that low and high levels of weathering lead to bacterial communities dominated by k-strategist (oligotrophic) bacteria, while moderately-weathered surfaces exhibited higher biodiversity and favored r-strategist (copiotrophic) microorganisms. The ongoing degradation processes on moderately-weathered surfaces created a heterogeneous habitat that fostered higher alpha biodiversity and an increased presence of specialist bacteria compared to less and highly-weathered surfaces. While almost all samples have the genetic potential to cycle N, S and P, the bacterial communities in moderately-weathered samples were primarily engaged in processes potentially related to stone degradation, such as nitrification, sulfur oxidation, biomineralization, siderophore production, and metal uptake. Thus, bacterial communities displayed characteristic metabolic features essential for adaptability within diverse ecological niches formed by weathering processes.