Extremophilic microbes have adapted to thrive in ecological niches characterized by harsh chemical/physical conditions such as, for example, very low/high temperature. Living organisms inhabiting these environments have developed peculiar mechanisms to cope with extreme conditions, in such a way that they mark the chemical-physical boundaries of life on Earth. Studying such mechanisms is stimulating from a basic research viewpoint and because of biotechnological applications.

Pseudoalteromonas species are a group of marine gamma-proteobacteria frequently isolated from a range of extreme environments, including cold habitats and deep-sea sediments. Since deep-sea floors constitute almost 60% of the Earth's surface and cold temperatures represent the most common of the extreme conditions, the genus Pseudoalteromonas can be considered one of the most important model systems for studying microbial adaptation. Particularly, among all Pseudoalteromonas representatives, P. haloplanktis TAC125 has recently gained a central role. This bacterium was isolated from seawater sampled along the Antarctic ice-shell and is considered one of the model organisms of cold-adapted bacteria. It is capable of thriving in a wide temperature range and it has been suggested as an alternative host for the soluble overproduction of heterologous proteins, given its ability to rapidly multiply at low temperatures.

In this review, we will present an overview of the recent advances in the characterization of Pseudoalteromonas strains and, more importantly, in the understanding of their evolutionary and chemical-physical strategies to face such a broad array of extreme conditions. A particular attention will be given to systems-biology approaches in the study of the above-mentioned topics, as genome-scale datasets (e.g. genomics, proteomics, phenomics) are beginning to expand for this group of organisms. In this context, a specific section dedicated to P. haloplanktis TAC125 will be presented to address the recent efforts in the elucidation of the metabolic rewiring of the organisms in its natural environment (Antarctica).

极端微生物已经适应在以苛刻的化学/物理条件为特征的生态位中茁壮成长，例如非常低/高温。居住在这些环境中的生物体已经形成了应对极端条件的特殊机制，它们标志着地球上生命的化学-物理边界。从基础研究的角度和生物技术的应用来看，研究这种机制是令人兴奋的。

假交替单胞菌属是一组海洋γ-变形菌，经常从一系列极端环境中分离出来，包括寒冷的栖息地和深海沉积物。由于深海海底几乎占地球表面的 60%，而寒冷的温度代表了最常见的极端条件，因此假交替单胞菌属可以被认为是研究微生物适应的最重要的模型系统之一。特别是，在所有Pseudoalteromonas代表中，P. haloplanktisTAC125 最近获得了核心作用。这种细菌是从沿南极冰壳采集的海水中分离出来的，被认为是适应寒冷的细菌的模式生物之一。它能够在很宽的温度范围内繁衍生息，并且由于其在低温下快速繁殖的能力，它已被建议作为异源蛋白质可溶性过量生产的替代宿主。

在这篇综述中，我们将概述假交替单胞菌菌株表征的最新进展，更重要的是，了解它们面对如此广泛的极端条件的进化和化学物理策略。由于基因组规模的数据集（例如基因组学、蛋白质组学、表型组学）开始针对这组生物进行扩展，因此在上述主题的研究中将特别关注系统生物学方法。在这种情况下，将介绍一个专门讨论P. haloplanktis TAC125 的部分，以解决最近在阐明生物在其自然环境（南极洲）中的代谢重新布线方面所做的努力。