Microbial Growth and Control

• Alcohols denature Proteins
• Antiseptics are less toxic than disinfectants
• Silver nitrate is used to prevent eye infections in newborns.
• Ethylene oxide must be applied in a special chamber because it is so reactive.
• If there is one bacteria at 12:00 noon, how many bacteria will there be at 3:00 if the generation time is 30 minutes?

  64
• Sterilize kills everything including spores
• A disinfectant kills most cells but not spores on surface
• An antisepsis reduces microbes on tissue
• An autoclave kills everything with high temperature and pressure
• Ultraviolent radiation uses thymine dimers, low penetrating power
• Ionizing radiation uses reactive molecules, high penetrating power
• Pasteurization kills pathogens and reduces spoilage organisms
• Filtration is used for heat senstive materials
• Alcohol disinfects with 10-15 minutes of soaking by denaturing proteins
• Phenols disrupt cell membranes and denatures proteins, e.g. Lysol
• Heavy metals bind to proteins and inactivates them
• Ethylene oxide is used for Pacemakers
• Chlorine oxidizes Proteins
• Phenolics are used as disinfectants
• Psychrotrophs will grow at room temperature
• Rank the following in the order of the temperatures they grow at starting at the highest going to the lowest.

  Hyperthermophile, Thermophile, Mesophile, & Psychrophile
• The stationary phase is always caused by a lack of nutrients. True or False

  False
• What are the cardinal growth temperatures?

  • Minimum
  • Maximum
  • Optimum
• What is the correct order for the phase of microbial growth?

  Lag, Log/exponential, Stationary, & Death
• Which pathogen will likely grow in your refrigerator?

  • Psychrotroph
  • Psychrophile
• Bacterial #'s don't change as they are damaged or dead, adjusting to the new medium components needed for growth

  Lag phase
• Bacterial #'s don't change. The nutrients may have run out or the # of dying equals the # or growing

  Stationary phase
• Bacteria are increasing in number

  Log or exponential phase
• Accumulation toxins cause bacteria number to go down

  Death phase
• ATP is directly made during glycolysis and the electron transport train
• Oxygen, carbon dioxide, and sulfur can act as terminal electron acceptors
• Pasteurization

  • Reduces spoilage organisms
  • Eliminates pathogens
• Glycolysis occurs during fermentation?
• Psychrotrophs can grow at room temperature and in the cold.
• When temperatures decrease, microbial growth slows until the minimum is reached due to enzyme denaturation. True or False

  False
• What are the products of glycolysis?

  • ATP
  • Pyruvate
  • NADH
• Carbon dioxide is made by the electron transport chain. True or False

  False
• Obligate Aerobe bacteria grow where in semi-solid media?

  Only at the top
• Facultative Aerobe bacteria grow where in semi-solid media?

  Throughout but mostly at the top
• Aerotolerant anaerobe bacteria grow where in semi-solid media?

  Evenly throughout the tube