Degradation of ancient Maya carved tuff stone at Copan and its bacterial bioconservation

Abstract Much stone sculptural and architectural heritage is crumbling, especially in intense tropical environments. This exemplified by significant losses on carvings made of tuff at the Classic Maya site Copan. Here we demonstrate that Copan primarily decays due to stress generated humidity-related clay swelling resulting spalling material loss, a damaging process appears be facilitated microbial bioweathering minerals (particularly feldspars). Such weathering not prevented traditional polymer- alkoxysilane-based consolidants applied past. As an alternative such unsuccessful conservation treatments, prove effectiveness bioconservation treatment based application sterile nutritional solution selectively activates stone´s indigenous bacteria able produce CaCO 3 biocement. The generates bond with original matrix significantly strengthen areas while unexpectedly, bacterial exopolymeric substances (EPS) impart hydrophobicity reduce swelling. environmentally-friendly effectively safely preserve fragile stones conditions, opening possibility for its widespread area, elsewhere.