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Title: Bacterial Growth
Description: 1st year Undergraduate, Biomedical science Gram staining and requirements for growth
Description: 1st year Undergraduate, Biomedical science Gram staining and requirements for growth
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Bacterial Growth
Prokaryotic fission (Binary fission) → asexual reproduction → cells genetically identical
Depending on species and conditions, as quickly as 20 minutes
Gram staining
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Hans Christian Gram created a test to differentiate types of bacteria
...
Gram-positive bacteria, are stained by the violet dye because of a thick layer of
peptidoglycan
...
Compared with Gram-positive bacteria, Gram-negative bacteria are more resistant against
antibodies because of their impenetrable cell wall
These bacteria have a wide variety of applications ranging from medical treatment to
industrial use
...
Immunity (antibiotics)
Growth
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An increase in size
An increase in number
An increase in understanding
A Development of additional skills
Becoming more complex
The increase in cellular constituents and may result in an increase in a microorganisms size,
population numbers, or both
...
Time depends on species
and other environmental factors
...
Due less nutrient, toxins released critical
density, etc
Death – Limited nutrients and build up of toxins
...
Cells revert to
dormant stage or spore stage
...
Bacteria have selectively permeable membranes and therefore can be strongly affected my the
environment
...
If there is no water present then the bacteria can die
...
Water activity (aw) affected by temperature, pressure, and chemical environment
...
Why does Temperature have such an effect? High vs Low?
Psychrophiles (cryophiles) (0-20° C)
Most microorganisms are unicellular
Mesophiles (20 – 45° C)
Enzyme catalysed reactions
Lipid Bilayer
Thermophile (over 45° C)
pH
pH represents the amount of H ions present
every microorganism has a minimum, an optimum and a maximum pH for growth
...
0
Yeasts and moulds are generally more acid tolerant than bacteria and can grow at lower pH values
...
5 are usually not easily spoiled by bacteria but are more susceptible to
spoilage by yeasts and moulds
Title: Bacterial Growth
Description: 1st year Undergraduate, Biomedical science Gram staining and requirements for growth
Description: 1st year Undergraduate, Biomedical science Gram staining and requirements for growth