EARTH SCIENCES SEMINAR ROOM Tuesday 8th April - 4.00 pm
Javier Cuadros, Department of Earth Sciences, Natural History Museum, London
Confinement appears to be essential at the mineral-microbial interface and has an effect on both, microbial development and mineral formation. The role of confinement starts before life itself. Prebiotic molecules had to be concentrated from water or gas and "confined", possibly within clay interlayers, where they could react, be protected from adverse physical and chemical conditions, and perhaps also where specific reactions were catalysed.
Microorganisms frequently confine themselves within organic or inorganic walls for a number of reasons such as protection and feeding. They build exopolysaccharide capsules, burrow into mineral grains, etc. Close contact or confinement within mineral grains is arguably the habitat of the largest portion of existing microorganisms.
Microbial confinement has a feed-back effect on minerals. Microbes burrowing into mineral grains contribute to mineral weathering. Confined spaces inhabited by microorganisms, such as burrows, biofilms, exoskeletons of dead microbial algae, have chemical conditions different from the surrounding environment and impact mineral crystallization. For example, glauconite originates largely in connection to biological decay within marine shells. Microbial activity can thus control to some extent the chemistry, mineralogy and formation rate of the neoformed phases. Clay minerals are obviously affected by microbially-mediated confinement of mineral-solution systems, as they are typically formed in the range of conditions in which these processes take place.
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