Quiz 3 Flashcards
Quiz 3
Psychrophiles
0-20°C
Psychrotrophs
0-35°C
Mesophiles
15-45°C
Thermophiles
45-80°C
Hyperthermophiles
65-113°C
Cardinal temperatures
Rage that a particular bacterium grows in. Minimum, optimum and maximum temperatures.
Prodigiosin
Pigment on Serratia marcescens that changes depending on temperatures. (red)
What are the major effects that heat may have on a cell?
It can disrupt membranes and transport systems by melting the lipids in the membrane.
What is Botulism and name a bacteria that can cause it
Deadly form of food poisoning
Clostridium botulinum. It exists in either spores or vegetative cells.
pH
measure of acidity.
The lower its value the more acid the food.
Acid foods contain enough acid to block the growth of bacteria or destroy them more rapidly when heated.
Citric Acids
Added to foods in an effort to lower their pH and prevent spoilage or toxin formation.
Acidophiles
pH 0-5.5
Ferroplasnma spp
Neutrophiles
pH 5.5-8.0
E.coli
Alkaliphiles
pH 8.0-11.5
Bacillus alcalophilus
Buffer
Chemical added to growth media to prevent shifts in the pH of the media
osmosis
Net movement of water molecules across semi-permeable membrane, from low solute to high solute.
Hypertonic
More solutes outside of the cell
Water will move out of the cell in order to create equal osmotic pressure.
Plasmolysis
Cell shrinkage in a hypertonic solution.
Water moves out of the cell so it shrinks
Hypotonic
More solutes inside the cell.
Water will move into the cell.
Lysis
During a hypotonic solution. Water moves into the cell causing it to expand = lysis.
Isotonic
Balanced solute concentration on both sides. In and out of cell.
Halophiles
Will grow in higher than 3% NaCl
Extreme halophiles
Require very high salt concentration. Up to 30%.
Found in the Dead Sea etc.
Osmotolerant
Bacteria that have adapted mechanisms to survive in a wider range of osmotic environments.
Aerobes
Require oxygen
Anaerobes
Cannon survive in the presence of oxygen.
Facultative anaerobes
Can grow with or without oxygen.
Microaerophiles
Prefer a reduced oxygen atmosphere.
Aerotolerant
Do not use oxygen, but are not killed by it.
Fluid Thioglycollate Medium
FTM
It permits growth of anaerobic bacteria
Growth patterns can help distinguish aerotolerance and oxygen requirements of bacteria.
Thioglycollate is the oxygen reducing agent
Resazurin
The chemical indicator in FTM. The pinkish color indicates presence of oxygen.
Anaerobe Jar System
Permits the growth of anaerobic and facultative bacteria.
The sachet reduces oxygen in the container and produces carbon. The plates are put in the jar. The sachet is opened, and oxygen indicator is placed in the jar and then jar is immediately closed.
Mannitol Salt Agar
MSA is a selective and differential media. Contains 7% NaCl. very high salt concentration.
It makes it selective for bacteria that can grow at higher salt.
GPCs
It also has sugar mannitol, which some bacteria use via fermentation. A by-product of fermentation is acid which has a low pH. So the phenol red pH indicator in the MSA will turn yellow if the bacteria utilized the mannitol.
Used for id of Staphylococcus aureus (BSL2)
Phenol red
pH indicator in MSA media. Its yellow at low pH and red at high pH. So, bacteria that produced acid (formations by using the mannitol) will turn the media yellow. Bacteria that can grow in salt will grow but the media will remain red. Bacteria that can grow in in high salt and use the mannitol will turn the media yellow. So, S. aureus will turn the MSA media yellow.
MacFarland
Standard method that uses a prepared test tube of a specific turbidity. Then, you would prepare a broth of the bacterium to be tested to the same turbidity.
Sensitive
Resistance
Intermediate
The diameter of the zone of inhibition is measures and the size determines if the bacteria is S, R or I.
The size and interpretation is specific to each bacteria-antibiotic pair and is references in a chart.
Aerobe from stock bacteria
Pseudomonas flourescens
Facultative anaerobic from lab
Escherichia coli
Produced prodigiosin during lab
Serratia marcescens
Bacterium that is Halophilic
Staphylococcus aureus
New stock bacteria
o Alcaligenes viscolactis (GNR)
o Citrobacter freundii (GNR)
o Enterobacter aerogenes (GNR)
o Moraxella catarrhalis (GNC)
Turbidity
Absorbance or Optical Density of the sample
Bacteriostatic
Stops bacterial growth
Bacteriocidal
Kills bacteria
Antiseptic
Stops or slows down growth.
On the body
Disinfectant
Kills, slow growth. May not kill spores, viruses or fungi
On nonliving surfaces
Sterile
Free from ALL bacteria or other living organisms
Sanitizer
To reduce disease-causing microbes to safe levels.
Phenol coefficient
Measure of the disinfecting power of a germicidal solution in relation to phenol. 1.0 means the chemical agent is as effective as phenol.
