A novel microbial dissolution-reprecipitation pathway for bio-sintering of limestone for biocement production.

In nature, remarkable geological structures, such as stromatolites, thrombolites, and beachrocks, are formed through biocementation, a process involving the successive dissolution and reprecipitation of CaCO(3). This research demonstrates mimicking natural cement via bio-sintering of limestone, a process that involves successive dissolution and reprecipitation of limestone facilitated by bacteria under ambient environmental conditions. When the bacterium Acetobacter aceti (ATCC 15973) was introduced into a mixture of ethanol and limestone powder, the pH dropped rapidly, leading to the dissolution of limestone into calcium acetate. After ethanol was fully consumed, the pH gradually increased due to acetate oxidation, causing biocement crystals to precipitate. All reaction rates were measured, and the products characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, quantitative X-ray diffraction, and a particle size analyzer. The detailed characterization indicates that the precipitate is mainly calcite and that the dissolved calcium carbonate sinters microbially. This pathway offers new opportunities in biocementation research by using limestone as a direct calcium source, reducing the overall carbon footprint, and eliminating the need for urea or other chemical additives. The biocement produced shows potential for practical applications in soil stabilization, eco-concrete, and other sustainable construction solutions, providing a foundation for environmentally conscious alternatives in next-generation construction.  KEY POINTS: • Novel bio-sintering emulates natural CaCO(3) cementation via microbial action. • Acetobacter aceti mediates limestone dissolution and calcite precipitation. • The process forms calcite without urea or synthetic additives.