Protocols for the Study of Microbe–Mineral Interactions in Modern Microbialites

Abstract

Microbialites are organo - sedimentary structures formed by the direct or indirect action of microorganisms . Fossil stromatolites (laminated microbialites) constitute the oldest reliable traces of life , a fact that generates considerable interest in how these structures are formed and what biogenic traces can be preserved . Although found extensively in the fossil record , these structures are restricted today to a few marine and freshwater settings . Microbialites have a dual nature , where mineral and microbial roles are highly imbri - cated . This attribute poses a serious challenge for study from both a biological and mineralogical point of view . Here we detail protocols for sampling design , collection , fixation , and storage , propose a flowchart to carry out molecular surveys of microbialite microbial communities , and review a variety of correlative microscopies (light , confocal laser scanning , and electron and X -ray microscopies) to analyze the mineral - ogy and spatial distribution of microbialite components . These protocols are accompanied by potential solutions to problems related to the complexity of these systems .