# Carbonatogenic Bacteria in the Maros-Pangkep Karst: Protectors or Threat to Prehistoric Paintings?

## TL;DR

This study explores whether carbonatogenic bacteria in a karst region help preserve or threaten prehistoric cave paintings by producing calcium carbonate.

## Contribution

The study identifies and characterizes carbonatogenic bacteria from prehistoric cave paintings and evaluates their calcium carbonate precipitation potential.

## Key findings

- Two bacterial isolates showed high calcium carbonate precipitation, producing 2.45 mg/ml and 1.80 mg/ml respectively.
- The isolates were identified as Bacillus cereus strain bk and Bacillus sp. NCCP-428.
- The findings suggest potential applications in stone artwork conservation and strategies to prevent excessive calcium carbonate deposition.

## Abstract

The Maros-Pangkep karst region hosts prehistoric cave paintings recognized by UNESCO as a world cultural heritage site. The presence of calcium carbonate (CaCO3) on the surface of these artworks suggests the involvement of carbonatogenic bacteria, which facilitate CaCO3 production or deposition. While these bacteria have been explored for their potential in stone artwork conservation, their role in either preserving or obscuring prehistoric paintings remains unclear. This study aims to identify carbonatogenic bacteria associated with the Maros-Pangkep cave paintings and evaluate their CaCO3 precipitation potential. Bacteria were isolated using Calcium Carbonate Precipitation (CCP) medium, and their CaCO3 precipitation capacity was assessed by measuring precipitate mass and ammonia (NH3) levels. Molecular identification was conducted using 16S rRNA gene sequencing. Eighteen bacterial isolates were obtained from swab samples collected in Parewe and Bulu Sipong caves, ten of which were identified as carbonatogenic. Among these, two isolates exhibited the highest CaCO3 precipitation: Ps1-d produced 2.45 ± 0.07 mg/ml CaCO3 with 946.3 ± 26.3 mg/l NH3, while Ps8-b produced 1.80 ± 0.05 mg/ml CaCO3 with 763.4 ± 21.2 mg/l NH3. Molecular analysis identified Ps1-d as Bacillus cereus strain bk and Ps8-b as Bacillus sp. NCCP-428. These findings have significant implications for both (1) the potential application of carbonatogenic bacteria in the conservation and restoration of stone artworks and (2) the development of strategies to inhibit excessive CaCO3 deposition to prevent the obscuration of cultural heritage paintings.