Microscopic view of Shigella sonnei (Public Domain)


 Factors of Survival
Shigella sonnei is susceptible to Where Shigella lives in the human body (Public Domain)multiple environmental factors that do not make it possible to live outside the human body for long. One of the environmental factors is the dryness of the habitat. In the human intestinal tract it is very moist, and outside a human body it is not very successful finding such a moist place. Another environmental factor is the temperature that Shigella sonnei needs to survive, which is about 37 degrees Celsius. If this bacterial disease does not find a habitat with the proper temperature it will die.  The last major environmental factor is the acid level or the pH of the habitat. Shigella sonnei can survive in a pH ranging from 7 to 7.5. Any pH lower or higher than that will cause death to the bacterial infection. When the bacteria are excreted from the human body, it can only survive for a mere 30 minutes in the human feces because the pH decreases to 6.5 or 6. The human body is nearly the only environment that can provide all the conditions that Shigella sonnei needs to survive.
 Shigella sonnei growth plate (Permission Granted)
Structural Function
Shigella sonnei cannot be considered motile because it does not have flagella, but it facilitates movement by using a polymerizing actin. This motile movement is not recognizable to the human body and it saves energy for the bacteria. Shigella sonnei did develop a gene through evolution from E. coli that makes this bacterial infection non-lactose ferment. This bacterial infection is rod shaped which helps uptake nutrients into the cytoplasm better than other shapes because of its surface-to-volume ratio.

Now that you have explored why Shigella sonnei is only viable in the human body, take a look at what it likes to consume inside of you! GO!

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