Interactions between microorganisms and clay minerals: New insights and broader applications

Interactions between microorganisms and clay minerals are ubiquitous in nature and are involved in the formation and transformation of clay minerals and the global cycles of many elements. The fungi/actinomyces in microbes are also associated with clay minerals, but bacteria are more widely linked. These interactions are also involved in the adsorption and fixation of heavy metals and the decomposition of organic pollutants in soil. Knowledge of these interactions can be utilised for the refinement and purification of clay minerals in industry. This review provides an overview of recent studies and obtains insights into the interactions between microorganisms and clay minerals. Microorganisms can induce the nucleation and growth of clay minerals. The metabolism of microorganisms can also degrade and transform clay minerals. The interaction between microorganisms and clay minerals promots the transformation of smectite to illite (S-I) and vice versa (I-S). Such interactions significantly contribute to the global cycles of various elements, such as Al, Si, Mg, Fe, P, S, C, and N. Microorganisms and clay minerals can form complexes and composite materials that adsorb heavy metals such as Cu, Cr, Cd, Pb, Zn, Co, Ni, Ag, and Hg. Microorganism adhesion to clay minerals is involved in the synergistic adsorption and decomposition of organic pollutants in soil and water. This literature review indicates that knowledge of the interactions between microorganisms and clay minerals has been significantly deepened over recent years. However, the interaction between microorganisms and clay minerals under natural geological conditions and the inherent mechanisms involved are not yet well understood. Future work on interactions between microorganisms and clay minerals has great implications for handling atmospheric micro/nano particle pollutants, understanding the formation, alteration and diagenesis of clay minerals and other related minerals, tracking primitive life on Earth and exploring extraterrestrial planets.