Some like it cold: understanding the survival strategies of psychrophiles

Abstract

Much of the Earth's surface, both marine and terrestrial, is either periodically or permanently cold. Although habitats that are largely or continuously frozen are generally considered to be inhospitable to life, psychrophilic organisms have managed to survive in these environments. This is attributed to their innate adaptive capacity to cope with cold and its associated stresses. Here, we review the various environmental, physiological and molecular adaptations that psychrophilic microorganisms use to thrive under adverse conditions. We also discuss the impact of modern "omic" technologies in developing an improved understanding of these adaptations, highlighting recent work in this growing field.

Figure 1. Distribution of psychrophile genomes and metagenomes in different cold ecosystems

(A) Pie chart of the relative proportions of sequenced psychrophile genomes per ecological niche. Psychrophile genome statistics were determined by key word search against the GOLD database. The geographic distribution of marine genomes is given in the chart. (B) Pie chart of the relative proportions of psychrophile metagenomes derived from different ecological niches. The psychrophile metagenomes include all datasets submitted to the MG-RAST database for which temperature data are available (lower than 15°C).

Figure 2

Common structural modifications of psychrophilic enzymes resulting in decreased thermostability, increased flexibility and increased specific activity.

Figure 3

Common physiological adaptations in a psychrophilic prokaryote.