Bacterial and diesease
- Created by: Hazel99
- Created on: 22-09-16 17:43
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- Measuring the growth of bacterial cultures
- Haemocytometer
- Specialised thick microscope slide with a rectangle chamber that holds a standard volume of liquid.
- 0.1mm3
- Specialised thick microscope slide with a rectangle chamber that holds a standard volume of liquid.
- the sample of nutrient broth is diluted by half with an equal volume of tryan blue
- A dye that stains dead cells
- So you can identify the living cells
- measurements at regular time intervals throughout the life of a bacterial colony.
- 16 squares is usually counted and the mean calculated
- A dye that stains dead cells
- Optical methods
- Measuring the number of cells in a culture is by Turbidimetry
- A specialised form of colorimetry
- As the number of bacterial cells in a culture increase it becomes increasingly cloudy looking or turbid
- Turbid = absorbs more light
- Colorimeter measures how much light passes through
- A relationship between the turbity of the culture and the number of bacterial cells present.
- Dilution plating
- Total viable cell count
- Not possible to workout individual colonies
- Problem solved by diluting the original culture in stages until a point is reached the colonies can be counted.
- Two or more plates where individual colonies can reach a mean.
- Accuracy = checked using a haemocytometer
- Area and mass of fungi
- Measure diameter of the patches of mycelium
- Compare growth rates in different conditions
- Can find optimum temperature to grow.
- Test the dry mass of the Microorganism
- Best done in liquid broth removed at regular intervals and separated in a centrifugation or filtering
- Material dried so no more mass is lost.
- The conditions which produce the greatest dry mass of fungus are the optimum ones for growth.
- Material dried so no more mass is lost.
- Best done in liquid broth removed at regular intervals and separated in a centrifugation or filtering
- Haemocytometer
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