Genes, smoking, and treatment response

Abstract

Stable alkaline conditions are caused by an unusual combination of climatic, geological, and topological conditions. Soda lakes represent the most stable high-pH environments on Earth and commonly have pH values above 11.5. These environments are characteristically associated with a low Mg2+, Ca2+ geology together with rates of evaporation that exceed any inflow. Such environments are found in arid and semi-arid areas of tropical or subtropical rain-shadow deserts such as in North America or in the continental interiors of Asia. Other examples are found in areas of tectonic rifting such as the East African Rift Valley. Despite apparently hostile conditions, these caustic lakes are the most productive aquatic environments in the world, with productivity rates an order of magnitude greater than the mean rate for all aquatic environments on Earth. Alkaliphilic cyanobacteria drive these systems, providing fixed carbon that is utilized by a vast range of alkaliphilic aerobic and anaerobic chemo-organotrophs, notably halomonads, bacilli and clostridia methanogens. There is also active cycling of nitrogen and sulfur in the lakes, brought about by novel alkaliphilic groups.