ABSTRACT

Many microorganisms are capable of inducing carbonate mineral precipitation under certain conditions. Not to be confused with structured biomineralization in eukaryotes for bones and shells, bacteria can indirectly cause precipitation, being a by-product of alkalinity increasing metabolisms, such as photosynthesis, urea hydrolysis, sulfate reduction, nitrate reduction, and iron reduction. The geologic record holds many examples of microbially produced carbonates, and presently the process is being utilized to manipulate porous media properties (De Muynck et al., 2010; Riding, 2000). Applications in porous media are numerous but can generally be divided into either increasing the material strength or reducing permeability (Phillips et al., 2013). The microbiology

26.1 Introduction .......................................................................................................................... 891 26.2 Biological Processes ............................................................................................................. 893

26.2.1 Alkalinity-Producing Metabolisms in the Subsurface ............................................. 893 26.2.1.1 Urea Hydrolysis .......................................................................................... 895 26.2.1.2 Denitriœcation ............................................................................................ 895 26.2.1.3 Sulfate Reduction ....................................................................................... 896 26.2.1.4 Iron Reduction ...........................................................................................897