Microbial metabolism Flashcards
Lag phase?
- Initial period of adaptation to a new environment2. Increase in metabolic activity3. Sensitive to antimicrobials4. Little to no cell division
During what stage(s) are bacteria susceptible to antimicrobials?
- Lag2. Exponential
Exponential phase
- Rapid multiplication by binary fission2. Most susceptible to antibiotics
Stationary phase
- Nutrients depleted, waste products accumulate2. Decreased growth rate3. Spore forming bacteria initiate sporulation
During what growth phase do spore forming bacteria begin sporulation?
Stationary phase
Decline phase
More bacteria die than are generated
Obligate aerobe
Bacteria that require oxygen and metabolize by respiration
Obligate anaerobe
Bacteria that are inhibited or killed by oxygen and utilize fermentation exclusively for energy production
Facultative anaerobe
- Bacteria that grow well under aerobic or anaerobic conditions. If oxygen is available they respire, if not they use fermentation2. Majority of bacteria
Microaerophilic
Require 5-10% oxygen for optimal growth
What does catalase (or peroxidase) do?
Breaks down H2O2 into O2 and H2O
What does superoxide dismutase do?
Detoxifies O2- to H2O and O2
What must bacteria synthesize to make nucleic acids, making it a target for antibiotics?
Folate
What do quinolones target?
DNA gyrase
What drug class targets DNA gyrase?
Quinolones
What does rifampin target?
Bacterial DNA-dependent RNA polymerase
What is the precursor subunit of peptidoglycan?
UDP-N-acetyl muramic acid
Where is UDP-N-acetyl muramic acid synthesized?
Bacterial cytoplasm
What is added to the 3rd carbon of UDP-N-acetyl glucosamine to make UDP-N-acetyl muramic acid?
Lactyl group
What occurs once UDP-NAM is made?
5 amino acids are added to it
What happens to the UDP-NAM-pentapeptide after it is formed?
Transferred from UDP to bactoprenol phosphate at membrane surface
What happens to bactoprenol-NAM-pentapeptide to form the final disaccharide-pentapeptide precursor product?
NAG is transferred from UDP-NAG to it
How are the peptide side chains linked together?
Transpeptidation
What is transpeptidation?
- Cross linking of peptide chains by peptide bond exchange2. Occurs on outer leaflet of plasma membrane
Where does transpeptidation occur?
Outer leaflet of plasma membrane