Psychrophiles-Cold-adapted hydrocarbon-degrading microorganisms.

Throughout the year a high percentage of the biosphere, about 85%, is permanently exposed to temperatures below 5 C. Despite the inhospitable nature of low-temperature environments they are successfully colonized by cold-adapted microorganisms (both psychrophiles and psychrotolerant). Microbiological investigation in cold habitats have primarily focused on the assessment of microbial biodiversity and community structure prior to human contamination. However, the biotechnological potentialities of psychrophilic and psychrotolerant microorganisms deriving from their cold-adaptation has been investigated more and more. An example of which is the decontamination of hydrocarbon-polluted cold environments. A wide variety of autochthonous microorganisms have been proven to possess the ability to degrade aliphatic and aromatic hydrocarbons at low temperatures, thus playing a significant role in the in situ biodegradation process. In this context, the aim of the chapter is to present an overview of psychrophilic and psychrotolerant hydrocarbon-degrading bacteria inhabiting cold habitats, spanning from Alpine sites to deep ocean and Polar climates to groundwaters of temperate areas. Taxonomic, physiological, and genetic features of hydrocarbon-degrading isolates (mainly bacteria, but also fungi and yeasts) will be summarized alongside a discussion of ecological aspects.