Microbes experience various forms of stress, including chemical stress from toxic compounds, physical stress like heat, and nutrient limitations. Microbes have developed stress responses to temporarily increase their tolerance limits. Stress responses can help bacteria transition from free-living to host-invading pathogens. Osmotic stress occurs when there are sudden changes in the solute concentration around a cell, causing changes in water movement across the cell membrane. Bacteria experience osmotic stress under variable, extremely low, or extremely high osmotic pressures in their environment.

1. MICROBIALSTRESS
RESPONSE
PRAGYA TYAGI
MICROBIOLOGY

2.  Just like human beings, microbes have to deal with continuous stress. However, stress
 for microbes is different from the stress humans are used to-it causes damage to
 macromolecules, membranes, proteins and nucleic acids.
 It can be chemical stress, caused by toxic and harmful compounds, or physical stress.
 For example heat.

3. • A limited supply of nutrients can also be regarded as stress. Microbes have developed stress responses,
to temporarily increase tolerance limits.
• Some stress responses facilitate bacterial transition from a free living organism to a host-invading
pathogen.
• When supplied with sufficient nutrients and optimal growth temperature, pH ,Oxygen levels and solute
concentrations, will grow at a maximum growth rate characteristics for the organisms.
• Variations in these parameters can affect the maximum growth rate and thus, can represent an
environmental stress for the microbe.
• As a result, bacteria live in a constant state of stress.

4. • Cells respond to hypoosmotic environment by sudden rapid cell swelling, but within
minutes, they start to return to their original volume

5. • Osmotic stress-----
• Bacteria experience osmotic stress when the osmotic pressure of their
environment is variable, extremely low, or extremely high.
• Osmotic stress tolerance mechanisms determine whether bacteria survive or
grow because osmotic stress profoundly affects the structure, physics, and
chemistry of bacterial cells.
• Water flows out of cell as their medium become more concentrated and into
cells as their medium becomes more dilute.
• Bacteria attenuates such water fluxes by accumulating and releasing electrolytes
and small organic solutes.

6. Basically Osmotic stress is a sudden change in the solute
concentration around a cell, causing change in the movement of
water across its cell Membrane.
OSMOTIC STRESS
HYPEROSMOTIC HYPOOSMOTIC

7. THANKYOU