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27 Cards in this Set
- Front
- Back
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What types of pathogenic bacteria have higher optimal growth temp?
What types of pathogenic bacteria have lower optimal growth temp? |
- pyrogenic bacteria = fever-producing
- Cutaneous pathogens |
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What type of environment do pathogenic bacteria require to replicate?
Sporeformers are “designed” for survival outside host by becoming more resistant to? |
- aqueous environment
- drying, heat, disinfection |
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What do obligate (strict) aerobes require?
MOA? Do they ferment substrates? |
- O2 for growth
- use aerobic respiration, oxidative pathways - NO |
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How do obligate (strict) anaerobes? respond to O2?
How does it metabolize? |
- it’s toxic to them
- fermentative metabolism |
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How do facultative anaerobes react to O2?
MOA? Which MOA allows them to grow faster? |
- grow in the presence or absence of O2
- use aerobic respiration and fermentation - grow FASTER aerobically than anaerobically. |
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How do microaerophilic aerobes react to O2?
MOA? |
- Need O2 - BUT TOO MUCH CAN KILL
- use aerobic respiration, not fermentation |
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How do aerotolerant anaerobes react to O2?
MOA? |
- Tolerate a small amount of O2
- use fermentation |
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What common enzymes do aerobes, facultative anaerobes, and aerotolerant anaerobes have?
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- Superoxide dismutase, (catalase or peroxidase)
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What is the rxn involved with superoxide dismutase (SOD)
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2O2 2-· + 2H+ --> O2 + H2O2
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What is the rxn involved with catalase?
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2H202 --> 2H20 + 02
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What is the rxn involved with peroxidase?
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H2O2 + 2H+ --> 2H2O
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What are capnophilic organisms?
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- “CO2-loving” pathogens
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What are essential nutrients for pathogenic bacteria?
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- Carbon (for carbs, ptns, fats), Nitrogen (ptn and nucleic acid synthesis), essential amino acids, vitamins, sulfur, phosphorus, trace elements, and iron
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One mole of glucose yields?
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- 2 moles of ATP (“substrate-linked phosphorylation” ) and 2 moles of reduced NAD (NADH)
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What does each pyruvate yield through the citric acid cycle?
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- 1 ATP, 3 NADH, 1 FADH2
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During aerobic respiration, what does each NADH oxidized produce?
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- 3 ATP
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What is the terminal electron acceptor for anaerobic respiration?
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- NO 3-, SO4 2-, CO2, NOT O2
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MOA of bacteria reproduced by binary fission?
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- non-growing cell in stationary phase -> origin replicates -> one Ori (origin of replication) migrates across cell -> DNA replication continues around circle -> Ori replicates, starting new round -> septum divides cell
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What are the growth phases of bacteria in culture?
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- Lag phase -> logarithmic phase -> stationary phase -> death
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What is doubling time?
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- Generation time of bacteria population increasing by doubling
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What are problems in measuring bacterial growth?
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- requires uniform suspension
- not useful for low conc of bacteria <10^4 colonies per ml |
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What is targeted for bacterial killing?
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- Membrane disruption or ptn denaturation
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What is sterilization?
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- Autoclave (inc P inc steam temp) or Ethylene oxide gas (kill bact w/o elevated heat) to destroy all microbial forms (vegetative cells and spores).
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What is disinfection?
Why is disinfectant bad? |
- Use of physical or chemical means to destroy most bacterial cells and spores on surfaces and objects.
- b/c it destroys only 99.9%, which means that there is still enough for infection (i.e. infectious dose of E. coli O157 = 10 organisms |
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What is pasteurization?
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- Heat treatment between 62oC and 74oC for seconds to minutes to kill vegetative bacterial cells without altering nature of food product.
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What is antisepsis?
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- Use of chemical agents on skin or other tissues to remove or inhibit bacterial agents.
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How do you measure bacterial growth?
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- Viability counts (w/ serial 10-fold dilutions) or optical density (w/ spectrophotometer) of broth cultures measure bacterial growth.
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