Preliminary investigation on a novel bacterium from a hydrothermal vent for biocementation of soils

¹ Department of Engineering, University of Palermo, Viale delle Scienze, Bd. 8, 90128, Palermo, Italy
² Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Viale delle Scienze, Bd. 16, 90128, Palermo, Italy
³ NBFC National Biodiversity Future Center, Piazza Marina, 61, 90133 Palermo, Italy

^* Corresponding author: marco.rosone@unipa.it

Abstract

This study presents the results of a multi-step investigation aimed at identifying and testing a novel bacterial strain for applications in soil biocementation via Microbially Induced Calcium Carbonate Precipitation. A total of 61 bacterial strains were isolated from a hydrothermal vent in Sicily (Italy) and screened for ureolytic activity and calcium carbonate production. Through progressive quantitative and qualitative evaluations, strain UB-59 was selected as the most effective candidate. The biocementation potential of the selected strain was investigated through a series of multi-scale laboratory tests, ranging from microscopic observations to sample-scale experiments under both static and flow conditions. Results demonstrated significant CaCO₃ precipitation in small-scale tests, with a marked reduction in efficiency at larger volumes due to non-uniform distribution, leading to crust formation primarily at the sample edges. Microscopical observations and chemical analyses confirmed the presence of calcium carbonate coatings filling the voids between sand grains in the outer regions, while inner portions remained poorly cemented. Although there is the need for protocol optimization, thorough quantification of the hydro-mechanical behaviour of the treated samples, and complete genome sequencing of UB-59, these findings highlight the potential of the selected strain for soil biocementation.