Adaptation of microorganism in environment- microbial ecology
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The document discusses how microorganisms adapt to various environments. It notes that microbes can adapt to changing conditions within and between hosts through various strategies. These include producing proteins and enzymes to adapt to different temperatures, pH levels, salt concentrations, and other environmental factors. The document also describes several types of extremophiles that have adapted to survive in extreme environments through strategies like accumulating salts to balance osmotic pressure.
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Adaptation of microorganism in environment- microbial ecology
- 1. Adaptation of microorganism in environment
- 2. • Microbial symbiotic associations, which are pervasive, can be beneficial (mutualistic), neutral (commensal), or harmful (pathogenic) to the host animal. • Within symbioses, microbes can exploit the host for space and nutrients or as a vector for dissemination to other environments. • Both within and between hosts, microbes experience changing environmental conditions to which they must adapt for optimal fitness and for maintenance of symbiotic associations. • SURVIVAL
- 3. • Microorganisms are adapted for optimum functioning in their normal physiological environments. • Any extreme change in environmental conditions from the optimum inflicts a stress on an organism. • The extent of the change will determine whether the organism is killed, ceases growth, or has an increased lag time and reduced growth rate. • Most bacteria are able to tolerate small changes in an environmental parameter and can adapt over the time scale of minutes, hours, or days (Hill and others 1995). • Microorganisms do this by both yielding to the stress conditions and making suitable provisions for survival or attempting to resist the stress (Herbert 1989). For most organisms, this tolerance can be pushed to maximum limits if the cell is provided with sufficient opportunity to sense and adapt to the deteriorating environment.
- 4. Microorganisms will produce proteins and enzymes to adapt to various environments • Entire groups of microorganisms such as psychrophiles, acidophiles, and halophiles have adapted their lifestyles to prefer these extreme environments. Psychrophiles are microorganisms that can grow at 0 °C and have an optimum growth temperature of 15 °C or less and a temperature maximum of around 20 °C. • Acidophiles are microorganisms that have their growth optimum between about pH 1.0 and 5.5, and halophiles are microorganisms that require high levels of sodium chloride for growth such as 2.8 molal and up to 6.2 molal for extreme halophiles. • Changes in environmental conditions away from the optimal value can cause the induction of many elaborate stress responses. • These strategies are generally directed at survival rather than growth.
- 5. Extreme Environments • Microorganisms are found in a wide range of environments that differ in pH, temperature, atmospheric pressure, salinity, water availability, and ionizing radiation. • In some environments, these conditions can be at either end of a continuum (e.g., very alkaline or acidic; extremely hot or cold). Such environments are called extreme environments. • The microorganisms that survive in such environments are described as extremophiles. • Although extreme environments are usually considered to have decreased microbial diversity, as judged by the microorganisms that can be cultured, with the increased use of molecular detection techniques, it appears that many contain a surprising diversity of microorganisms. • Work to establish relationships between the microorganisms that can be observed and detected by molecular techniques and culturable microorganisms is ongoing. • Many microbial genera have specific requirements for survival in extreme environments. For example, a high sodium ion concentration is required to maintain membrane integrity in many halophilic procaryotes, including members of the genus Halobacterium. Halobacteria require a sodium ion concentration of at least 1.5 M, and about 3 to 4 M for optimum growth.
- 6. • Microbial life at high salt concentrations is phylogenetically very diverse. Hypersaline environments with salt concentrations up to NaCl saturation are inhabited by halophilic and highly halotolerant representatives of all three domains of life: Archaea, Bacteria and Eukarya. • The mechanisms used by these salt-requiring or highly salt- tolerant microorganisms to withstand the high salt concentrations, and in many cases also to adapt their physiology to changes in the salt concentrations in their environments, are diverse as well. • Biological membranes are permeable to water. Therefore, water moves into and out of cells driven by differences in water activity between the cytoplasm and the outside medium.
- 8. • To maintain a high osmotic pressure inside the cells, different strategies can be used, which are as follows: • The ‘salt-in’ strategy where osmotic balance is achieved by accumulating high concentrations of inorganic salts in the medium. As Na+ ions are excluded as much as possible from cells in all three domains of life, the ‘salt-in’ strategy is based on KCl rather than on NaCl as the main intracellular salt.
- 9. • https://jb.asm.org/content/199/15/e00883-16 • https://onlinelibrary.wiley.com/doi/pdf/10.1111 /j.1541-4337.2004.tb00057.x • https://academic.oup.com/femsre/article/42/3/3 53/4909803 • Prescott Microbiology