Effects of Osmotic Stress and Temperature on Microbial Growth
Effect of Osmotic Stress and Temperature on Microbial Growth
BIO 3400-002L – Microbiology Lab
1
Effect of Osmotic Stress and Temperature on Microbial Growth
Luiz Felipe Isidoro
ABSTRACT
Evolution allowed primitive forms of life to develop proteins and enzymes that made it possible for life to evolve under environments with hostile conditions, such as high salt and heat. More specifically, some bacteria selected genes that code for peptides with stronger intermolecular forces, coping with extreme heat, or for compatible solutes, which accumulate to compensate osmotic stress. The present study utilizes multiple bacterial strains to assess their ability to overcome unfavorable conditions and promote growth. To achieve this goal, three species of bacteria were incubated under different salt concentrations, and six were used in two separate procedures where incubation took place at various temperatures. These organisms were classified based on the observations made after the assays conducted.
INTRODUCTION
For the most primordial forms of life, osmotic stress and variations in temperature, when not fatal, were harmful for their growth. Nowadays, however, microorganisms can be found almost anywhere we can think of, independently of the conditions inherent to each of these places. It took billions of years of evolution to result in bacteria and archaea adapting to harsh conditions, such as extreme heat or
Effect of Osmotic Stress and Temperature on Microbial Growth
2
hypertonicity, for example. During this long period of time, novel proteins were positively selected according to each environment, whose nature would keep their function at their optimum.
In a high salt environment, there is a gradient of water flowing from the interior of a microbial cell to the medium, in order to establish isotonicity; conversely, in low salt enviroments, the water gradient is from the medium into the cell. Although both lead to alterations in the shape of
BIO 3400-002L – Microbiology Lab
1
Effect of Osmotic Stress and Temperature on Microbial Growth
Luiz Felipe Isidoro
ABSTRACT
Evolution allowed primitive forms of life to develop proteins and enzymes that made it possible for life to evolve under environments with hostile conditions, such as high salt and heat. More specifically, some bacteria selected genes that code for peptides with stronger intermolecular forces, coping with extreme heat, or for compatible solutes, which accumulate to compensate osmotic stress. The present study utilizes multiple bacterial strains to assess their ability to overcome unfavorable conditions and promote growth. To achieve this goal, three species of bacteria were incubated under different salt concentrations, and six were used in two separate procedures where incubation took place at various temperatures. These organisms were classified based on the observations made after the assays conducted.
INTRODUCTION
For the most primordial forms of life, osmotic stress and variations in temperature, when not fatal, were harmful for their growth. Nowadays, however, microorganisms can be found almost anywhere we can think of, independently of the conditions inherent to each of these places. It took billions of years of evolution to result in bacteria and archaea adapting to harsh conditions, such as extreme heat or
Effect of Osmotic Stress and Temperature on Microbial Growth
2
hypertonicity, for example. During this long period of time, novel proteins were positively selected according to each environment, whose nature would keep their function at their optimum.
In a high salt environment, there is a gradient of water flowing from the interior of a microbial cell to the medium, in order to establish isotonicity; conversely, in low salt enviroments, the water gradient is from the medium into the cell. Although both lead to alterations in the shape of
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