Microbial interactions during carbonate biomineralization via urea hydrolysis metabolic pathway

Abstract

Due to its versatile applications, microbially induced carbonate precipitation (MICP) via urea hydrolysis has gained considerable interest in diverse fields, ranging from soil sciences, applied microbiology, geomicrobiology to civil and environmental engineering. The present study aims to elucidate the interactions by which microbial cells are mediating the MICP process. To this end, MICP soil column experiments were performed and bio-cemented samples were preserved for field emission scanning electron microscopy imaging. Our results and observations show that microbial cells act as nucleation sites for calcite crystal precipitation, often undergoing cell entombment during calcite crystal growth. However, the surviving bacterial cells present on the surface of precipitated calcite crystals interact to form a network of bacterial chains resulting in interconnectivity between different calcite crystals which directs the growth of these crystals. This growth occurs on the surface of soil particles as well as in the formation of cementation bonds at inter-particle contacts, controlling the morphology of precipitated calcite crystals, coated soil particle roughness, and stiffness of bio-cemented soil. These microbial interactions have significant influence on biologically induced mineralization processes in geomicrobiology.