Microbe – Erionite Intimacy or How to Survive When Things Get Tough

Growth experiments using Natrialba magadii, a haloalkaliphilic archaea isolated from the saline-alkaline brine of Lake Magadi in the East African Rift Zone, were conducted to investigate a hypothesized relationship between erionite, the most common zeolite mineral phase found in the trona producing areas of the lake, and the preservation of microbial cells during evaporation. Haloalkaliphilic archea accumulate K⁺ to maintain osmotic balance and, as erionite has a high cation exchange capacity with a strong affinity for K⁺ as well as a structure that contains exchangeable H₂O, N. magadii cultured in the presence of erionite may access this exchangeable K⁺ and H₂O in the erionite to maintain osmotic balance as evaporite mineral phases precipitate from the brine during evaporation.

Liquid media cultures of N. magadii, grown in the presence and absence of erionite, were allowed to evaporate to dryness under aseptic conditions in a laboratory incubator. Mineral precipitates were analyzed using scanning electron microscopy. Results indicate that microcosms consisting of both N. magadii and erionite contained preserved cells whereas no preserved cells were seen in microcosms comprised only of N. magadii in liquid media. This observed relationship between erionite and preserved microbial “fossils” suggests an intimate relationship between Natrialba magadii and erionite and specifically the association with potassium cycling.