Fig. 4: Mechanistic map of artificial lights impacting the phototrophic microbiome on monuments in indoor environments.

In brief, Cyanobacteria govern community composition and ecological functions (involved in carbon fixation, denitrification, and dissimilatory sulfate reduction, as well as organic acid production) related to biodeterioration of the phototrophic microbiome on monuments under artificial lights. Due to the weak absorbance at ~530 nm of photosynthetic pigments, green light can decrease Cyanobacteria abundances and their functional traits, further influencing the compositional and functional profiles of its oriented heterotrophic microorganisms related to biodeterioration and finally weakening the biodeterioration potential of the whole phototrophic microbiome on monuments, all of which help for the long-term conservation of historical monuments worldwide.