Microbial Growth and It's Control Flashcards
increase in number not size
Microbial Growth
Enumerate the process of Bianry Fissions
- Cell elongate and DNA is replicated
- Plasma Membrane begins to construct and new wall is made
- Cross-wall forms, completely separating the two DNA copies.
- Cell separate
time required for a cell to divide (and its population to double)
Generation time
What are the phases of growth of bacteria
Lag Phase
Log Phase
Stationary Phase
Death Phase
Intense activity preparing for population growth, but no increase in population
Lag Phase
Logarithmic, or exponential, increase in population
Log Phase
Period of equilibrium; microbial deaths balance production of new cells
Stationary Phase
Population is decreasing at a logarithmic rate
Deathphase
What are requirement for microbial growth for PHYSICAL REQUIREMENT
Temperature
pH
Osmotic pressure
What are requirement for microbial growth for CHEMICAL REQUIREMENT
C
N, S, P
Trace Elements
O2
Orgranic growth factors
What is the rate of growth of microbial with a temperature of -10 to 20 Celsius
Psychrophiles
What is the rate of growth of microbial with a temperature of 0 to 30 degree Celsius
Psychrotrophs
What is the rate of growth of microbial with a temperature of 10 to 50 degree Celsius
Mesophiles
What is the rate of growth of microbial with a temperature of 40 to 70 degree Celsius
Thermophiles
What is the rate of growth of microbial with a temperature of 70 to 110 degree Celsius
Hyperthermophiles
Temperatures in this range destroy most microbes, although lower temperatures take more time
70 to 130 degree celsius or 160 to 260 Fahrenheit
Very slow bacterial growth
50 to 60 degree celsius or 120 to 140 Fahrenheit
Rapid growth of bacteria; some may produce twins
20 to 50 degree celsius or 60 to 120 Fahrenheit
Many bacteria survive; some may grow
5 to15 degree celsius or 40 to 60 Fahrenheit
Refrigerator tempratures; may allow slow growth of spoilage of bacteria, very few pathogens
0 to 5 degree celsius or 10 to 40 Fahrenheit
No significant growth below freezing
-30 to 0 degree celsius or -20 Fahrenheit to 10 Fahrenheit
What is the pH of most Bacteria
6.5-7.5
even up to 1 pH
acidophiles
wider range, usually 5 - 6 pH
Fungi
What is used when cultured bacteria produce acids that inhibit growth?
Buffers
Hypertonic
High osmotic pressure
Hypotonic
Low osmotic pressure
Swelling
Low osmotic pressure
Plasmolysis (shrinkage)
High osmotic pressure
Adding salt can presrve food
High osmotic pressure
Can grow at high sal concentrations
Extreme halophiles
Under these conditions, the solute concentration in the cell is equivalent to a solute concentration of 0.85% sodium chloride (NaCl).
Cell in isotonic solution
If the concentration of solutes such as NaCl is higher in the surrounding medium than in the cell (the environment is hypertonic), water tends to leave the cell. Growth of the cell is inhibited.
Plasmolyzed cell in hypertonic solution
