Source of sterile practice media Source of sterile practice media Once you obtai

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Source of sterile practice media
Source of sterile practice media

Once you obtained isolation at a particular dilution, did you continue to have isolation on subsequent dilution plates? Is this what you would expectt Why or whry not? What is the primary negative consequence of not spreading the inoculsam evenly over the agar surfacet 4 To get isolated colonies on a plate, omly about 300 cells cam be in the inocuham. What will bappen if the cell density of the inoculam significanthy exceeds this namber 5 Suppose you have tvo organisms in a micture and Organism A is 1,000 times more abundant than Organism B. Will you (without counting on good luck!) be able to isolate Organism B using the spread plate technique? Explain your answer

Explanation / Answer

1   2. Isolation is a separation of a particular microorganism from the mixed populations that exist in nature.

Here we need to make serial dilutions and the blank.

Then we need to transfer 1 ml from each dilution on the agar plates.

Here we can observe more diluted plates will have lesser number of colonies which will be ditributed more or less sparsely in the plates which may be transferred (subcultured) to other media or agar slants for further study.

Hence once we have isolated on a particular dilution, we need not go for subsequent dilutions only our intention is is isolation of microorganisms.

or else, if our intention is to calcuate the organisms in different dilutions, then we need to go for subsequent dilutions.

3. If the inoculum is not spreading evenly over the agar surface, we will not get the isolated colonies. The theory behind spread-plate technique is that petri dish spuns, at some stage, single cells will be deposited with the bent glass rod on to the agar surface. Some of these cells will be separated from each other by a distance sufficient to allow the colonies that develop to be free from each other.

4. The original sample is usually diluted so that the number of colonies developing on the plate will fall in the range of 30 - 300. Within this range the count be accurate, and the possibility of interference of the growth of one organism with that of another is minimized.

5.Yes. If we two organisms, Oaganism A and organism B, and the one is more abundant than the other, we can isolate organism B using spread plate technique.

The colonies of organism can be selected and diluted . Then it can be spread on agar plates to get isolated colonis. or else, if we cannot differentiate the oranism A from organism B, then also we can take mixture of colonies and can can be diluted further and then spread on agar plates to get isolated colonis.

3 1. Overstaining the bacterial smear may cause the cell wall disruption or totally destroy the cell wall which results in the loss of true morphological characteristics of the bacterial cell. Over-staining must be avoided, as this is an intense stain, and prolonged application colours the cell protoplasm in addition to nuclei and bacteria.

2. In understaining, the cells may lose the stain when washed with alcohol or water.

3. We can write this after your observation in laboratory.

4 a. The coccus would be better suited for a dry environment than rod. A sphere has less surface area for thevolume, as such, less moisture will be lost by osmosis in a dry environment.

b. In a moist environment, the higher surface area to volume ratio of a rod shaped bacterium will allow greater efficiency in transferring water and solutes.

2 1. Floculent - d. Membrane at the top

Sediment - c. Growth at the bottom

Ring - b. Growth at the top around the edge

Pellicle - e. Suspended chunks or pieces

Uniform fine turbidity - a. Evenly cloudy throughout

2. The factors would be incubation temperature, Growth medium and atmosphere (aerobic or anaerobic).

Incubation temperature plays very important role. Different microorganisms need different optimum temperature for their growth.

In growth medium, different components will be added in a measured quantity. If quantity differes here, it affects the growth.

Oxygen- if it is present, allows aerobic oranisms. if it is absent allows anaerobic microorganisms.  

2 1. Filiform - 5. Rough texture with crusty appearence

Spreading edge - 3. Solid growth seeming to radiate at th edge

Transparent - 4. Almost invisible, or easy to see light through

Pigmented - 2. smooth texture solid edge

2. 1. On agar plates, we can isolate the microorganisms from mixed culture or from any other sample.

2.Easy to identify microorganisms base on thie colony characteristics and pigmntation.

3. we can count the bacteria based on viable count.

3. Agar slants better suited for maintainig stock cultures. Agar slants provide more surface area for growth to the microorganisms. These are easier to store and transport then petriplates. In a slant, it is easier to streak than a horizontal surface. Thay are also less readily contaminated.

4. Fig not given here.

  

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