Microorganisms in Permafrost Ice Wedge and their Resuscitation Promoting Factor
Katayama Taiki and Michiko Tanaka
from: Cold-Adapted Microorganisms (Edited by: Isao Yumoto). Caister Academic Press, U.K. (2013)
Bacteria and fungi preserved for long periods at sub-zero temperatures in Alaskan and Siberian permafrost ice wedge were reactivated on agar by aerobic cultivation at 15°C. Culturable bacteria differed among ice samples, but several phylogenetic groups were closely related to those in other frozen environments. Incubation under controlled temperatures and the Arrhenius profiles of bacterial isolates from the Alaskan ice wedge indicated that they could grow at temperatures below 0°C without remarkable alterations in their cellular process. The novel ice wedge isolates, Glaciibacter superstes AHU1791T and Tomitella biformata AHU1821T, increased membrane fluidity at lower to subzero temperatures by modulating the fatty acid composition of the cytoplasmic membrane. Reactivating the non-culturable state of ice wedge isolates using resuscitation promoting factor (Rpf) and culturing melted ice wedge with Rpf provided indirect evidence that non-culturable bacteria exist within the ice wedge in situ. Bacteria in ice wedges can change their membrane fatty acid composition and/or structure to survive, but may then lose the ability to grow under laboratory conditions, as a final adaptation to long periods in a frozen natural environment read more ...