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Why were you asked to incubate the plates at two different temperatures? Be specific....

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zorico91 | Honors

Posted May 29, 2012 at 2:25 AM via web

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Why were you asked to incubate the plates at two different temperatures? Be specific. What is the likely source (reservoir) of organisms that grew best at 37 degrees Celsius, and how do they survive at room temperature without nutrients?

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bandmanjoe | Middle School Teacher | (Level 1) Senior Educator

Posted May 29, 2012 at 8:28 PM (Answer #1)

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Any time you are asked to incubate bacteria at two differing temperatures, we are trying to figure out which temperature would provide an optimum environment in terms of bacterial production.  Since the 37 degree Celsius temperature had the better bacterial production between the two, I would be willing to bet the source of the bacterial cells was from somewhere on the interior of the human body.  If you do the conversion of 37 degrees Celsius to degrees Fahrenheit, you come up with 98.6 degrees Fahrenheit, which is the average temperature of the human body.  As to the last question, room temperature is significantly lower than the human body temperature of 98.6, so the bacteria will have to lower their metabolic rate to survive at all.  They will have a fairly hard time existing at room temperature with no nutrients, even at a reduced metabolic rate.

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vrmanoj | College Teacher | eNoter

Posted May 29, 2012 at 5:09 AM (Answer #2)

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a. Petri plates containing nutrients and inoculated with micro-organisms are generally incubated at two or more of different temperatures to ascertain their optimum temperature for growth.


b. The likely source (reservoir) of organisms that grew best at 37 degrees celsius must be traced back to where you inoculated the organisms from. Most likely, it could be from a sample taken from a human body (living) as the optimal temperature there is 37 degrees celsius.

 

c. They cannot survive at room temperature without nutrients. The organisms would enter the decline phase very fast as they cannot multiply without nutrients.

 

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