Microbial growth Flashcards
list the physical requirments for growth
Temperature, pH and osmotic pressure
list the chemical requirments for microbial growth
Supply of NCHOPS, supply of trace elements and organic growth factors
Classify microbes into five groups, based on preferred temperature range
-10 - 20 (Psychrophiles)
0 - 30 (Psychrotrophs)
10-50 (Mesophiles)
40 - 70 (Thermophiles)
70 - 110 (Hyperthermophiles)
what is the prefered tempreture for Psychrophiles
-10 to 20
what is the prefered tempreture for Psychrotrophs
0 - 30
what is the prefered tempreture for Mesophiles
10 - 50
what is the prefered tempreture for Thermophiles
40 - 70
what is the prefered tempreture for Hyperthermophiles
70 - 110
what organsims grows in -10 - 20 degrees
Psychrophiles
what grows in tempretures 70 - 110 degrees
Hyperthermophiles
Identify why the pH of culture media is controlled
Majority of acids grow 6.5 - 7.5, fungi and yeasts prefer 5 - 6, therefore controlling the pH can restrict some growth.
Explain the importance of osmotic pressure to microbial growth
There are three type of osmotic pressure: isotonic, hypertonic and hypotonic environments, most microorganisms are inhibited by high sat and sugar environments.
there are some exceptions:
Halophiles - grow in high salt environments
Saccharoplies - grow in high sugar environments
Describe a use for each of the six elements NCHOPS in microbial growth
Nitrogen: synthesis of amino acids, DNA, RNA and proteins
Carbon: key for organic matter (catabolism and anabolism)
Hydrogen: Counter ion examples - OH and -COOH
Oxygen: Terminal electron acceptor in respiration
Phosphorus: Needed for ATP, NADP, DNA and RNA
Sulphur: Needed for the animal acids M&C and cofactors
list the six trace elements needed for microbial growth and what they do
Iron: Required for cytochromes in electron transport
Magnesium: Counter ion for nucleotides and ATP. Is also a cofactor to a number of enzymes.
Zinc: Controls hormonal regulation of cell division
Cobalt: Cofactor/part of vitamin B12
Copper: Cofactor in ATP production
Molybdenum: protein production and detoxification
how do aerobes avoid damage from toxic O2 species
Enzymes are able to break down the toxic oxygen through superoxide dismutase which breaks it down to H2O2 and oxygen. Then catalase produces water and oxygen, finally peroxide produces water.
list the three enzyme which break down toxic oxygen and their products
superoxide dismutase - H2O2
catalase - H2O + O2
peroxide - H2O
list the three enzyme which break down toxic oxygen
superoxide dismutase
catalase
peroxide
list the types of microbes classified by their oxygen requirments
Obligate Aerobes: grows with air
Facultative Anaerobes:Facilitates air to grow faster
Obligate Anaerobes: grows without air
Aerotolerant anaerobes: can tolerate air
Microaerophile: loves a small portion of air
Explain the purpose of organic growth factors annd their significance.
These are requirements for microbial growth hence they cannot be used or studied without sufficient growth factors.
list the six diffrent types of growth media (bacterial)
Agar - a compex polysaccharide made from not metabolised seeweed it liquifies at 100.
Chemically defined media - we know the exact chemial make up
Complex media -not all componenets are defined
Differential media - an indicatior in the media dectes certain traits
Selective media - supress unwanted grown and encourages others
Enrichment media - encourages growth of microbes
define anaerobic technique
reactive chemicals are added that remove oxygen, this allow for anerobic microbes to grow
describe candel jars
The candle inside the jar will extinguish when all of the oxygen has been depleted. These are crucial for studying canophiles (high carbon dioxide)
descripe the anaerobic jar
A jar which has machine attached that remove all of the oxygen present.
descride the Anaerobic chamber
atmosphere is stripped using chemicals and the are port are used for work.
Define colony and colony forming unit
Colony - population of cells arising from a single cell or spore or from a group of attached cells.
Colony forming unit (CFU) - Measure of the number of living (viable) cells in a sample that will grow, divide and form colonies, the streak plate method is used to isolate pure cultures.
Describe how single colonies can be isolated by using the streak plate method
The loop is sterilised to ensure pure culture is made, the streaking method is made to create a concentration gradient, the first streak is heavily concentrated and everytime the loop is sterilised and done the concentration lessens.
Define bacterial growth, including binary fission
Bacteria growth: binary fission is how bacterial growth occurs.
Binary fission: how bacteria reproduce, the DNA replicates, then the plasma membrane begins to cleave and finally the cell is split with cross walls and the cells separate.
describe the phases of microbial growth
Lag phase - is comparing the growth factors and feeding itself, (minimal growth occurs)
Exponential /log phase: rapid growth occurs
Stationary phase: bacterial growth is equal to bacterial deaths
Death phase: where cell lysis occurs (also in log phase)
Describe four methods of measuring cell growth
Plate count: The growth is diluted a number of record times, when it is possible to count the number is multiplied by the amount of dilution done.
Membrane filtration: water sample is filtered then grown on an agar plate.
Direct microscope count: glass slides with groves, are counted each box and an average is calculated.
Turbidity: spectrophotometer is used and the light that was able to shown through is able to be reverse engineered into an average.
