Bacterial Physiology Flashcards
What two enzymes do bacteria require to utilize oxygen?
(1) Superoxide dismutase
(2) Catalase
What are aerobes?
Bacteria that require oxygen for growth.
What are anaerobes?
Bacteria that do not require oxygen for growth.
What are obligate aerobes? Give examples.
Bacteria that grow only in the presence of oxygen.
Examples: Pseudomonas, Bacillus.
What are facultative anaerobes? Give examples.
Bacteria that grow in trace amounts of oxygen.
Example: Listeria monocytogenes.
What are obligate anaerobes? Give examples.
Back: Bacteria that strictly grow in the absence of oxygen and may die on exposure to oxygen.
Examples: Clostridia, Bacteroides.
What does “capnophilic” mean?
Capnophilic refers to bacteria that require an excess amount of CO₂ for growth.
What are phototropic bacteria?
Phototropic bacteria require sunlight for growth.
What is symbiosis in microbiology? Give an example of symbiosis between bacteria.
◾ Symbiosis refers to a phenomenon whereby the growth of one organism favors the growth of another organism.
◾ Example: Staphylococcus aureus streaked across Haemophilus influenzae favors its growth.
What is antagonism in microbiology? Give an example of antagonism between bacteria.
◾ Antagonism is when the growth of one organism is detrimental to the growth of another.
◾ Pseudomonas hampers the growth of gonococci.
Describe the bacterial growth curve,
(1) Lag Phase
◾ During this phase, bacteria are growing in size, but they are not undergoing binary fission.
◾ Hence, there is no increase in cell number.
(2) Log Phase
◾ This phase is also referred to as the exponential phase because there is a logarithmic increase in cell number.
◾ During this phase, the conditions are optimal for growth and binary fission occurs.
(3) Stationery Phase
◾ There is no net increase or decrease in cell number in this stage. In other words, cell growth (division) equals cell death.
(4) Death phase
◾ This phase is characterized by an exponential death of cells.
[Diagram]
What is alpha hemolysis?
Alpha hemolysis is partial or incomplete hemolysis, resulting in a greenish or brownish discoloration around the bacterial colonies due to the oxidation of hemoglobin to methemoglobin.
Give an example of a bacterium that exhibits alpha hemolysis.
Streptococcus pneumoniae
What is beta hemolysis?
Beta hemolysis is complete hemolysis, resulting in a clear, colorless zone around the bacterial colonies due to the production of hemolysins that completely lyse the RBCs, releasing hemoglobin.
Give an example of a bacterium that exhibits beta hemolysis.
Streptococcus pyogenes
