Halophiles 2010: Life in Saline Environments

摘要

The world of halophilic microorganisms is highly diverse. Microbes adapted to life at high salt concentrations are found in all three domains of life: Archaea , Bacteria , and Eucarya . In some ecosystems salt-loving microorganisms live in such large numbers that their presence can be recognized without the need for a microscope. The brines of saltern crystallizer ponds worldwide are colored pink-red by Archaea ( Haloquadratum and other representatives of the Halobacteriales ), Bacteria ( Salinibacter ), and Eucarya ( Dunaliella salina ).Hypersaline environments such as saltern pond brines and natural salt lakes present the ecologist with relatively simple ecosystems with low diversity and high community densities. In such systems fundamental questions of biodiversity, selection, biogeography, and evolution in the microbial world can be investigated much more conveniently than in the far more complex freshwater and marine systems. The sediments of such water bodies, however, are often inhabited by extremely diverse, still incompletely explored microbial communities. Different types of halophiles have solved the problem how to cope with salt stress (and often with other forms of stress as well) in different ways, so that the study of microbial life at high salt concentrations can answer many basic questions on the adaptation of microorganisms to their environments. Most known halophiles are relatively easy to grow, and genera such as Halobacterium , Haloferax , and Haloarcula have become popular models for studies of the archaeal domain as they are much simpler to handle than methanogenic and hyperthermophilic Archaea . Some halophilic and halotolerant microorganisms have found interesting biotechnological applications as well, as shown in the last section of this report.