Biology Forums - Study Force

Legionella pneumophila in hospital water distribution systems has been linked to nosocomial infections. As a result, hospitals are investigating methods for eradicating Legionella in their water systems. Plate counts were used to determine the effects of heat (50°C), ozone, and UV light area. Data are shown below. Which is the most effective method? If the rates continue, which methods(s) will kill all the bacteria in 320 minutes?

table attached, help please  lol

UV light exposure at 23 degree C kills most bacteria in less time compared to other methods. In 20 minutes, UV light brought down the load of bacteria from 1x107 to 1x103 . Other methods took longer time to achieve the same.

So, UV light treatment of water is the most efficient method among all these.

If the rate continues, all the 3 methods i.e; 50 degree C, Ozone at 23 and UV at 23 can completely kill all the bacteria at 320min.

The effectiveness of the method is determined by the reduction in the CFU level in the plate after the application of the method. The more is the reduction higher is the efficiency of the method under the given time period. From the table given above UV light at 23 C shows maximum reduction under the 20 minutes, UV light is the most effective method. If the experiment is allowed to run for 320 minutes the heating at 50 C will kill the maximum number of bacteria possible, as the reduction in the CFU level is gradually decreasing with the increase in the time. The reduction is by a factor of 10 for each time the time applied is doubled. The increase in the time to 320 minutes will kill the maximum number of bacteria by heat as compared to the other methods.

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Thx