Lecture 5 Microbial Growth And Physiology Flashcards
Boiling is what temperature and how long
•100 degrees celcius
•30 minutes
Autoclave is at what temperature and for how long
120 degrees celcius
30 minutes
Dry heat is at what temperature and for how long
•150 degrees celcius
•120 minutes
What process do bacteria divide by
Binary fission
When the chromosome divides during binary fission what does it produce
Two identical copies
Is Bacterial growth described as exponential
Yes the generation time (time for bacterial mass to double) can be as fast as 20 minutes
What temperature does agar melt as
100 degrees celcius
What temperature does agar solidify at
40 degrees celcius
How is Agar sterilised
By Autoclaving
What do bacteria grow as on agar
As Colonies
How many cells/ml for growth in a liquid medium
10^9 cells/ml
For growth in a liquid medium what is position for incubation
Standing or Agitated
What are the growth phases of a Bacterial Culture
•Lag
•Log
•Stationary
•Death
Describe each of the growth phases of a Bacterial Culture
•Lag
Adaption
•Log
Cells multiply at the maximum rate
•Stationary
Lack of nutrients and build up of toxic metabolic intermediates means multiplication is balanced by cell death
•Death
Describe the two direct measurements of Bacterial growth
•Total Cell Count
Using microscope and counting chamber
•Total Viable Count
Cells in culture are diluted and spread on nutrient agar plates
Total viable count is a serial ___ -fold dilution
10
Name the indirect measurement of bacterial growth
•Turbidity
•Cloudiness
•Measure live and dead cells
What is the nm of a filter or prism in a Spectrophotometer
•540nm
In a Chemostat culture what is cell density controlled by
Nutrient Concentration
What is Growth rate controlled by in a Chemostat culture
By the flow rate of nutrient
What does Growth require
•Energy
•Building blocks required for construction of cellular machinery
•Appropriate environmental conditions
Name the nutrient requirements for Growth
– Water
– Carbon (carbohydrate)
– Nitrogen (protein)
– Inorganic salts Iron - siderophores – Oxidation of organic compounds
– (carbohydrates, lipids, proteins)
What temperature is required for Growth
20-110 degrees celcius
What pH is required for Growth
4.0-9.0
What type of Atmosphere for growth
O2/ No O2
What is Energy derived from
The enzymatic breakdown of organic substrates (carbohydrates,lipids or proteins) in a process called CATOBOLISM
What is Energy generated from CATABOLISM used to synthesise
Cellular constituents in a process called ANABOLISM
Catabolism + Anabolism =
Metabolism
Other than carbohydrates,lipids and proteins where else can bacteria derive energy from
•Plastic
•Rubber
•Toxic compounds like Phenol
What are Auxotrophs
The ability of individual bacterial species to produce their own cellular components will dictate its nutritional requirement
Obligate Aerobes grow only in the presence of what
O2
Obligate Anaerobes grown only in the absence and are killed by
O2
Facultative Anaerobes grow in the presence and absence and of
O2
What are Psychrophile bacteria
•Cold loving bacteria
•10-20 degrees Celsius
What are Mesophile bacteria
•Human body temperature
•Pathogens
•Opportunists
•20-40 degrees Celsius
What are Thermophile Bacteria
•Heat loving
•>60 degrees Celsius
Some bacteria can grow / survive in what ph
•acid
•alkali
