A LABORATORY-SCALE ALKALINE-LAKE MODEL OF MICROBE-ZEOLITE INTERACTIONS
Within these biologically harsh fluctuating environments, microbial archaea maintain osmotic balance by adjusting their intracellular ion concentration through accumulation and discharge of K+. Erionite consists of a three-dimensional framework of (Si,Al)O4 tetrahedra linked to form channel structures. Substitution of Al3+ for Si4+ results in a net negative charge balanced by extra-framework cations such as Na+ or K+ held within the channel structures; erionite has a strong preference for K+. H2O molecules also occupy the channel structures. Extra-framework cations and H2O are mobile and may be added or removed during precipitation – desiccation cycles. It is hypothesized that as evaporation and desiccation progress, microorganisms may associate with erionite to exploit the mobile K+ ions and water, in a sense using the erionite as a lifeboat for survival.
To explore this hypothesis, Natrialba magadii, a microbial archaea isolate from Lake Magadi in East Africa, was cultured in the laboratory in the presence and absence of erionite. Samples where evaporated to dryness under aerobic conditions and resulting mineral phases and desiccated microbes were documented using scanning electron microscopy with energy dispersive x-ray analysis. Preliminary results reveal unique mineral morphologies developed in inoculated erionite-containing samples compared to sterile controls and non-erionite samples suggesting the erionite-microbial relationship influences mineral morphology.