microbial metabolism

• What do microorganisms need energy for?

  To grow, move, reproduce, and defend
• What is required to produce energy in microorganisms?

  Nutrients and enzymes
• What happens to yeast in the presence of air?

  A larger amount of yeast is formed
• How do most microbes gain energy when oxygen is available?

  Via respiration
• What do anaerobes use to gain energy in the absence of oxygen?

  Fermentation
• What is fermentation?

  Conversion of carbohydrates to acids and alcohols
• What does yeast convert maltose into?

  Alcohol
• What do lactobacilli convert lactose into?

  Lactic acid
• What follows glycolysis in aerobic respiration?

  Pyruvate is oxidized to acetyl CoA
• What are the by-products of aerobic respiration?

  ATP and CO2
• What is the theoretical yield of ATP from one glucose molecule in aerobic respiration?

  38 ATP molecules
• What happens to pyruvate in anaerobic respiration?

  It is reduced to lactate or alcohol
• What is the theoretical yield of ATP from one glucose molecule in anaerobic respiration?

  2 ATP molecules
• What are obligate aerobes?

  Microbes that cannot survive without oxygen
• What are facultative anaerobes?

  Microbes that can respire using oxygen
• What is an example of an obligate anaerobe?

  Clostridium perfringens
• What is an example of a facultative anaerobe?

  Staphylococcus aureus
• What do microaerophilic organisms require?

  Oxygen in very small amounts
• What is an example of a capnophilic organism?

  Neisseria gonorrhoeae
• What is the main source of carbon for most cells?

  The atmosphere and organic compounds
• How do heterotrophs acquire carbon?

  From amino acids, sugars, and organic acids
• How do autotrophs acquire carbon?

  From CO2
• What are the modes of nutrition in microorganisms?

  • Photoautotrophic
  • Photoheterotrophic
  • Chemoautotrophic
  • Chemoheterotrophic
• What is an example of a photoautotrophic organism?

  Rhodospirillum rubrum
• What is an example of a chemoheterotrophic organism?

  Lactobacillus acidophilus
• What role do trace elements play in microbial nutrition?

  Essential for enzyme production
• What are siderophores?

  Iron binding molecules
• How do microbes use siderophores?

  To harvest iron from other bacteria
• What is the role of erythritol in Brucella abortus pathogenesis?

  Triggers virulence mechanisms in placental tissue
• What does the urease test detect?

  Presence of urease enzyme in bacteria
• What does a positive urease test indicate?

  Ammonia production changes pH to pink
• What does the citrate-utilisation test detect?

  Ability of bacteria to use citrate
• What indicates a positive citrate-utilisation test?

  Agar changes from green to blue
• What does the lactose test measure?

  Acid and/or gas production from lactose
• What indicates a positive lactose test?

  Broth changes from amber to pink
• What is mannitol salts agar used for?

  Detection of presumptive pathogenic staphylococci

  
• What do presumptive pathogens do on mannitol salts agar?

  Ferment mannitol and appear yellow

  
• What is Xylose lysine deoxycholate agar (XLD) used for?

  Detection of Salmonella
• How does Salmonella appear on XLD agar?

  Based on nutrient usage order

  
• What are the beneficial uses of microbial fermentation?

  • Production of wine
  • Production of vinegar
  • Production of lactic acid