President Miler is in a panic. Students have complained about an awful smell ema
ID: 62889 • Letter: P
Question
President Miler is in a panic. Students have complained about an awful smell emanating from Gibson Lake. The smell seems to be the resulting from a mysterious growth on the lake. Having heard of your expertise in microbiology, President Miller has a task for you. He wants you isolate the organism. Describe 2 methods and how they work by which you plan to identify individual colonies of bacteria and quantify the number and appearance of bacteria present in Gibson Lake other than through the use of a Petroff-Hausser Chamber.Explanation / Answer
The release of organic wastes from industries, agriculture, and urban communities into the lake allows the rapid growth of algal blooms. The rapid growth of algal blooms results in increase of organic matter compared to the capacity of microorganisms in water that are involved in breakdown and recycling of organic matter. The dead algae further add to the organic waste of the water body and water becomes deficient of oxygen.
Thus, to degrade the organic waste the anaerobic organisms are involved. This results in increase in population of anaerobic organisms. The anaerobic organisms degrade the organic waste and release the gases like methane and hydrogen sulphide, which affect the life of aerobic organisms. Hence, the foul-smell comes from the lake.
Isolation of organisms from lake is as follows:
The sample is collected in sterilized bags or bottles and has to be stored in refrigerator at 40C till further processing.
By using inoculation needle the sample is streaked for growth of isolated bacteria on agar medium. The inoculated plates are incubated at 370C for 24 hours.
The different colonies of bacteria can be identified with their morphology (size, shape, or color). Gram staining can be used to differentiate gram positive bacteria from gram negative. Selective medium can be used to identify the specific colony of bacteria.
The different methods used to quantify the number and appearance of bacteria is as follows:
Direct cell count- total cell count
Viable cell count- plate count
Measuring biomass- turbidity
Measuring cell products is done indicators such as acids etc.
In manual cell counting procedure, apart from Petroff-Hausser counting chamber, plating and CFU counting can be used to quantify the number of bacteria.
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