Premium
Spherical particles of halophilic archaea correlate with exposure to low water activity – implications for microbial survival in fluid inclusions of ancient halite
Author(s) -
Fendrihan S.,
DornmayrPfaffenhuemer M.,
Gerbl F. W.,
Holzinger A.,
Grösbacher M.,
Briza P.,
Erler A.,
Gruber C.,
Plätzer K.,
StanLotter H.
Publication year - 2012
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/j.1472-4669.2012.00337.x
Subject(s) - halite , haloarchaea , archaea , halophile , spheres , bacteria , biology , chemistry , biophysics , geology , paleontology , physics , gypsum , astronomy
Viable extremely halophilic archaea (haloarchaea) have been isolated from million‐year‐old salt deposits around the world; however, an explanation of their supposed longevity remains a fundamental challenge. Recently small roundish particles in fluid inclusions of 22 000‐ to 34 000‐year‐old halite were identified as haloarchaea capable of proliferation ( S chubert BA , L owenstein TK , T imofeeff MN , P arker MA , 2010, E nvironmental M icrobiology, 12, 440–454). Searching for a method to produce such particles in the laboratory, we exposed rod‐shaped cells of H alobacterium species to reduced external water activity (a w ). Gradual formation of spheres of about 0.4 μm diameter occurred in 4 m NaCl buffer of a w ≤ 0.75, but exposure to buffered 4 m LiCl (a w ≤ 0.73) split cells into spheres within seconds, with concomitant release of several proteins. From one rod, three or four spheres emerged, which re‐grew to normal rods in nutrient media. Biochemical properties of rods and spheres were similar, except for a markedly reduced ATP content (about 50‐fold) and an increased lag phase of spheres, as is known from dormant bacteria. The presence of viable particles of similar sizes in ancient fluid inclusions suggested that spheres might represent dormant states of haloarchaea. The easy production of spheres by lowering a w should facilitate their investigation and could help to understand the mechanisms for microbial survival over geological times.