Experimental Research on the Treatment of Saline-Alkali Diseases of Murals in Arzhai Grottoes With Salt-Tolerant Mineralizing Bacteria

Abstract

The degradation of cave murals due to saline-alkali conditions still poses a formidable challenge in the realm of cultural heritage conservation. This research proposes a novel methodology grounded in microbial mineralization technology. By leveraging Bacillus oceanicus, a newly isolated strain, calcium carbonate precipitation is induced under saline-alkali conditions, forming a protective layer. Experimental outcomes demonstrate that, in contrast to the conventional strain Bacillus pasteurii, B. oceanicus showcases exceptional salt tolerance. Its salt tolerance level in an identical saline environment is twice as high as that of B. pasteurii. Additionally, B. oceanicus can significantly enhance the mechanical properties of specimens. When compared with B. pasteurii, the unconfined compressive strength experiences a 47.9% increment, the cohesion increases by 83.18%, and the internal friction angle rises by 29.06%. In the simulation experiments addressing the saline-alkali-related pathologies of murals, compared to the untreated samples, the efflorescence height, efflorescence powder volume, and salt crust thickness of the samples treated by MICP (microbially induced calcite precipitation) decrease by 29.1%, 45.0%, and 36.4%, respectively. These findings accentuate the potential of B. oceanicus as an efficient and environmentally-friendly solution for the preservation of murals in saline-alkali settings, offering a fresh research perspective for cultural heritage conservation.