Tolerance of thermophilic and hyperthermophilic microorganisms to desiccation

Abstract

We examined short- and long-term desiccation tolerance of 31 strains of thermophilic and hyperthermophilic Archaea and thermophilic phylogenetically deep-branching Bacteria. Seventeen organisms showed a significant high ability to withstand desiccation. The desiccation tolerance turned out to be species-specific and was influenced by several parameters such as storage temperature, pH, substrate or presence of oxygen. All organisms showed a higher survival rate at low storage temperatures (-20 degrees C or below) than at room temperature. Anaerobic and microaerophilic strains are influenced negatively in their survival by the presence of oxygen during desiccation and storage. The desiccation tolerance of Sulfolobales strains is co-influenced by the pH and the substrate of the pre-culture. The distribution of desiccation tolerance in the phylogenetic tree of life is not domain specific. Surprisingly, there are dramatic differences in desiccation tolerance among organisms from the same order and even from closely related strains of the same genus. Our results show that tolerance of vegetative cells to desiccation is a common phenomenon of thermophilic and hyperthermophilic microorganisms although they originated from quite different non-arid habitats like boiling acidic springs or black smoker chimneys.

Survival of thermophilic and hyperthermophilic microorganisms after exposure to UV-C, ionizing radiation and desiccation

“…Such a correlation was indeed reported for Halobacterium salinarum NRC-1 (Kish et al 2009), Ustilago maydis (Holloman et al 2007), and bdelloide rotifers (Gladyshev and Meselson 2008). Since a surprisingly high tolerance of vegetative (hyper-) thermophilic Bacteria and Archaea to desiccation could be shown (Beblo et al 2009), in this study the resistance against ionizing and non-ionizing radiation of several (hyper-) thermophilic Bacteria and Archaea was investigated. Main goal was the determination of whether a correlation between desiccation tolerance and radiation resistance could also be found in this group of organisms.…”

“…The desiccation tolerance of Sulfolobales species is partly influenced by the growth substrate and pH (Beblo et al 2009). As a consequence Metallosphaera sedula, Sulfolobus metallicus and S. solfataricus were exposed to ionizing radiation after cultivation on different growth substrates (ore; elemental sulfur; knallgas) and after neutralization.…”

“…Desiccation under oxic conditions was performed as described previously (Beblo et al 2009). For the irradiation experiments, the cells were spread evenly on glass slides and dried under oxic conditions at room temperature.…”

“…Composition of the specific ore mixtures was pyrite, sphalerite, chalcopyrite, 33% w/v each (grain size \0.125 mm), or pyrite, sphalerite, 50% w/v each (grain size\0.125 mm) (Huber et al 1989). Neutralization by the addition of CaCO 3 was performed as described by Beblo et al 2009. In this study, it was observed that the survival rate of cells of Sulfolobus strains upon (periods of) water loss is increased if the media was neutralized before desiccation treatment.…”

Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection

“…Detailed resistance studies of vegetative thermophilic and hyperthermophilic Archaea have unexpectedly revealed tolerances against desiccation, vacuum and radiation (UV and g, Beblo et al, 2009). It is unclear however, whether these organisms could cope with the problematic and extremely harsh conditions during space travel, or lack of nutrients and low temperatures in extraterrestrial environments.…”