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Name: Prabhjot
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: 2002


Question:
Do microorganisms such as bacteria and yeast have a definite life span and die after attaining a particular age? If yes give life span of some bacterial species.



Replies:
Well this is hard to say, because bacteria reproduce asexually; therefore they split in half. Most bacteria have a very short generation time-from the time they are "born" until they split again. So it is hard to keep track of which bacteria are what age. You can keep a bacterial culture growing indefinitely if you provide it with the nutrients and conditions it needs. However, if the culture is growing in a closed environment, eventually their own waste will build up, poisoning them, and nutrients will run out because of the sheer numbers. They will eventually all die. Again this depends on the generation time of the organisms. It would be very difficult to keep track of one organism to see how long it lived if it was not able to divide and it had enough food, etc. to just die of "old age".

vanhoeck


This is an interesting question. Bacteria grow as individual cells that divide themselves to produce offspring. Thus, it is sometimes difficult to say what is one cell, what is a dividing cell, and what is a 'baby cell'. I guess your question regards a single cell, from division till it divides itself. Then their age can vary from a few hours to a few days. After that the cell either divides and has become two new individuals, or it degenerates and dies. An exception are bacteria that can build spores. These are fastidious 'mini-cells' that form when the conditions do not favor growth. They have a very low metabolism (compare this to hibernation) but they can come back to life if the conditions improve. Spores can remain viable for long periods, months to years. Some bacterial species, like Bacillus anthracis (causing Anthrax) can build spores that survive tens of years.

Trudy Wassenaar



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