The multifaceted life of microbes: Survival in varied environments

Abstract

The world of microorganisms comprises a vast diversity of living organisms, each with its individual set of genes, cellular components, and metabolic reactions that interact within the cell and communicate with the environment in many different ways. Microbes perform several key ecosystem functions. They provide a number of ecological services like soil formation, nutrient cycling, plant growth, bioremediation, source for pharmaceuticals, etc. Earth may be a home for more than 1012 microbial species. These species are present in varied environments, many of which for other life forms are extremely hostile. Microbes have been found in varied environments ranging from the tropics to the Arctic and Antarctica, from underground mines and oil fields to the stratosphere and the top of great mountains, from deserts to the Dead Sea, from aboveground hot springs to underwater hydrothermal vents. They can survive at pressures up to 110 MPa, at extreme acid (pH 0) to extreme alkaline (pH 12.8) conditions, at temperatures as high as 122 °C to as low as -20 °C, in toxic wastes, in organic solvents, heavy metals, guts of insects, roots of plants, low oxygen conditions, etc. These microorganisms are classified according to their habitats such as thermophiles/hyperthermophiles, psychrophiles, acidophiles and alkaliphiles, barophiles, and halophiles. Studies on microbial life, their diversity, physiology, genetics, ecology, and biochemistry can reveal a lot in terms of the characteristics of biological processes, such as biochemical limits to macromolecular stability and genetic instructions for constructing macromolecules. These organisms have also provided a number of clues to the origin and evolution of life. Further, a study of microbes in conflict environments has become vital in the field of research in astrobiology, since the microbes found in extreme environments may be analogous to potential life forms in other planets. In the present times of climate change, the study of microbes living at the edge of life has become even more important.