Bacteriology lecture 02 Growth and death of bacteria
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- In what temperature range do most pathogens grow
- 30-42 degrees C
- What are psychrophiles
- Bacteria that replicate well at cool, refrigerator temperature, such as Listeria monocytogenes
- What are obligate aerobes
- Require O2 for growth, do not ferment
- What are obligate anaerobes
- O2 is toxic, use fermentative metabolism
- What are Microaerophilic bacteria
- Grow best with small amounts of O2. Conduct respiration and fermentation
- What are facultative anaerobes
- Grow in the presence or absence of O2. Conduct respiration and fermentation
- What are aerotolerant anaerobes
- Can tolerate small amounts of O2. Use fermentation only
- What does it mean to have a CO2 requirement
- Capnophilic organisms grow best with elevated CO2 (pulmonary pathogens)
- What are some enzymes that inactivate toxic forms of oxygen
- Superoxide dismutase, Catalase, Peroxidase
- Is moisture required for all bacteria
- Universal requirement for vegetative growth, but not for endospores and some stationary phase cells
- What nutrients are required for bacteria
- Carbon, Nitrogen mainly; also iron, sulfur, phosphorus, and trace elements
- What does it mean for a pathogen to be fastidious
- They require additional nutrients from host, such as hemin or vitamins
- What are the characteristics of fermentation
- Does not require O2; molecules are reduced to pyruvate; pyruvate is reduced to organic acids, alcohol, and gases
- What are the characteristics of oxidative metabolism
- Produces more energy than fermentation; pyruvate enters the TCA cycle and generates 4CO2, 1FADH2, 6NADH, 2GTP; Aerobic respiration follows, generating a total of 38 moles of ATP per glucose
- What is anaerobic respiration
- A modified electron transport cascade that utilizes an alternative molecule as the terminal electron acceptor
- What is cultivation
- Most pathogenic bacteria can be grown in synthetic media
- What are the growth phases of bacteria
- Lag phase, Exponential phase, Stationary phase, Decline phase
- How is bacterial growth measured
- Viable cell counts; Optical density; Detection of metabolic by-products
- Define sterilization
- Use of physical or chemical means to destroy all microbial forms, including vegetative cells and spores
- Define Pasteurization
- Use of heat at high temperatures to rid potable liquids of vegetative bacterial cells
- Define disinfection
- Use of physical or chemical means to destroy most bacterial cells and spores. Not as thorough as sterilization
- Define antisepsis
- Use of chemical agents on the skin or other tissues to remove or inhibit bacterial agents
- If you hoped to assess whether a particular strain of bacteria produced spores, in what phase of growth would you attempt to detect them
- The decline phase
- Why do you suppose a culture of fermentative bacteria smells so foul after several hours of incubation
- Pyruvate is reduced to organic acids, alcohol, and gases