The influence of external factors on bacteriophages—review

The ability of bacteriophages to survive under unfavorable conditions is highly diversified. We summarize the influence of different external physical and chemical factors, such as temperature, acidity, and ions, on phage persistence. The relationships between a phage’s morphology and its survival abilities suggested by some authors are also discussed. A better understanding of the complex problem of phage sensitivity to external factors may be useful not only for those interested in pharmaceutical and agricultural applications of bacteriophages, but also for others working with phages

Ace Lake: three decades of research on a meromictic, Antarctic lake

Ace Lake (Vestfold Hills, Antarctica) has been investigated since the 1970s. Its close proximity to Davis Station has allowed year-long, as well as summer only, investigations. Ace Lake is a saline meromictic (permanently stratified) lake with strong physical and chemical gradients. The lake is one of the most studied lakes in continental Antarctica. Here we review the current knowledge of the history, the physical and chemical environment, community structure and functional dynamics of the mixolimnion, littoral benthic algal mats, the lower anoxic monimolimnion and the sediment within the monimolimnion. In common with other continental meromictic Antarctic lakes, Ace Lake possesses a truncated food web dominated by prokaryote and eukaryote microorganisms in the upper aerobic mixolimnion, and an anaerobic prokaryote community in the monimolimnion, where methanogenic Archaea, sulphate-reducing and sulphur-oxidizing bacteria occur. These communities are functional in winter at subzero temperatures, when mixotrophy plays an important role in survival in dominant photosynthetic eukaryotic microorganisms in the mixolimnion. The productivity of Ace Lake is comparable to other saline lakes in the Vestfold Hills, but higher than that seen in the more southerly McMurdo Dry Valley lakes. Finally we identify gaps in the current knowledge and avenues that demand further investigation, including comparisons with analogous lakes in the North Polar region

Polar Microalgae: Functional Genomics, Physiology, and the Environment

Microalgae underpin most foodwebs in polar regions as terrestrial primary production is too limited to support these complex and productive ecosystems. The success of microalgae in these extreme and highly variable ecosystems is rooted in their evolution and adaptation. The recent application of omics approaches in addition to biochemical and physiological measurements enabled a step change in our understanding of how these important organisms are adapted to their environment and how they have evolved from non-polar anchestors. This chapter is focused on diatoms and green algae as both groups of microalgae are most prevalent in polar regions. First genomes, transcriptomes, and reverse genetic tools have recently become available for representative species from both groups. They serve as important platforms to advance studies on their ecology, evolution, and adaptation. We highlight some of the key findings from these studies and link them with biochemical and physiological data to give insights into how genes and their products have shaped important microalgae in their diverse polar environments such as oceans, sea ice, permanently frozen lakes, snow and glaciers. Data from these studies will pave the way for understanding how these key organisms and their communities are going to respond to global climate change. They already provide novel genetic resources for various different biotechnological applications