Geomicrobiology of caves: A review

In this article, we provide a review of geomicrobiological interactions in caves, which are nutrient-limited environments containing a variety of redo x interfaces. Interactions of cave microorganisms and mineral environments lead to the dissolution of, or precipitation on, host rock and speleothems (secondary mineral formations). Metabolic processes of sulfur-, iron-, and manganese-oxidizing bacteria can generate considerable acidity, dissolving cave walls and formations. Examples of possible microbially influenced corr osion include corrosion residues (e.g., Lechuguilla and Spider caves, New M exico, USA), moonmilk from a number of caves (e.g., Spider Cave, New Mexico , and caves in the Italian Alps), and sulfuric acid speleogenesis and cave enlargement (e.g., Movile Cave, Romania, and Cueva de Villa Luz, Mexico). P recipitation processes in caves, as in surface environments, occur through active or passive processes. In caves, microbially induced mineralization i s documented in the formation of carbonates, moonmilk, silicates, clays, ir on and manganese oxides, sulfur, and saltpeter at scales ranging from the m icroscopic to landscape biokarst. Suggestions for future research are given to encourage a move from descriptive, qualitative studies to more experime ntal studies.