Microbiology FINAL

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jl167968
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81488
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Microbiology FINAL
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2011-04-25 10:45:46
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Environmental Food Biology
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Chapters 27 & 28
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  1. Where are microbes?
    everywhere on Earth that will support life
  2. Most microbes are __________? What are these essential for?
    saprophytes - essential to the decay of dead organic materials and the recycling of nutrients in nature
  3. What do many microbes produce?
    exoenzymes that break down large molecules of dead things in the environment, producing smaller molecules that they can absorb as nutrients
  4. What are Lichens?
    mutually beneficial association between fungus and algae (or cyanobacteria)
  5. How do fungus benefit in a Lichen?
    they receive carbohydrates from the algae (algae produces sugars that leak out of the cells - photosynthetic)
  6. How do algae benefit in a Lichen?
    receive minerals, water, and protection from the fungus (hyphae wrap around the algae)
  7. Where do most lichens grow? Why?
    surfaces of rocks and places most organisms can not grow, the fungi and algae support each other
  8. What are Mycorrhizae?
    mutually beneficial association between fungi and the roots of plants
  9. How does the fungus benefit in mycorrhizae?
    fungus receives carbohydrates from the plant
  10. How does a plant benefit in a mycorrhizae?
    the plant receives minerals and water from the fungus (roots also absorb these things but the fungal mycelium is denser and extends further, which gives it more access to nutrients)
  11. What plants benefit from the formation of mycorrhizae?
    ALL plants
  12. How much bacteria does a gram of soil contain?
    10^7 (plus numerous fungi and algae)
  13. Where are most bacteria in soil? Why?
    The top 10cm. Most nutrients are near the top and the fine particles of soil act like a filter and retain cells near the surface.
  14. What species are common in soil? What do these two have in common?
    Bacillus and Clostridium. They both form endospores.
  15. Why does soil smell musty and earthy? What is this produced by?
    Geosmin, chemical produced by species of Streptomyces
  16. Antibiotics are produced by what? Examples?
    Soil microorganisms - Streptomyces, Bacillus, Molds
  17. What is an essential part of proteins, amino acids, DNA, etc in cell?
    Nitrogen
  18. Where is the reservoir for nitrogen in the atmostphere?
    Nitrogen gas (N2)
  19. How do eukaryotic organisms obtain their nitrogen?
    They depend on certain bacteria to fix nitrogen gas and convert it to useable forms like ammonia (nh3) and nitrate (no3-), plants use the ammonia and nitrate, and the nitrogen gets passed up the food chain from there
  20. What bacteria is primarily responsible for nitrogen fixation?
    Rhizobium and cyanobacteria
  21. Where do Rhizobium live? What is its relationship with its habitat?
    nodules in the roots of legumes (peas, beans, etc) - mutually beneficial, plants provide shelter and nutrients, and the Rhizobium provides ammonia
  22. What are the nodules that Rhizobium live in caused by?
    infection of the roots by the Rhizobium
  23. Where do cyanobacteria usually reside? Where else can they live?
    They are aquatic, so deep ocean depths, but they can be found anywhere with enough moisture.
  24. All bacteria that fix nitrogen use what enzyme? What does that enzyme do?
    Nitrogenase, it converts nitrogen gas to ammonia (N2 --> NH3)
  25. How do nitrogen-fixing bacteria benefit soil?
    They make it more nutritious. Plants can use the ammonia or nitrate they produce.
  26. What species of bacteria is bad for soil. Why?
    Psuedomonas. They convert nitrate back to nitrogen gas, making the soil less nutritious and increasing the need for fertilizers on cropland.
  27. How much bacteria does groundwater usually contain? Why?
    few, because most microbes become trapped in soil as water seeps through
  28. When does the risk of groundwater contamination increase?
    when human activities bypass or overwhelm the filtering action of the soil (eg: wells, feedlots, broken septic tank systems)
  29. When is surface water most highly contaminated? Why?
    after rainfall, large numbers of soil microbes get washed into lakes and rivers
  30. How long does it take for surface water to return to normal after rainfall?
    72 hours
  31. It's estimated that more than how much of the oxygen in our atmosphere is produced by what?
    1/2, oceanic phytoplankton
  32. What are oceanic phytoplankton?
    free floating, photosynthetic organisms, including algae and cyanobacteria
  33. What is the most numerous photosynthetic organism on Earth?
    Prochlorococcus
  34. What is Prochlorococcus?
    oceanic phytoplankton
  35. Large increases in photosynthetic activity happens how often in the North Atlantic Ocean? Why?
    annually, spring thawing of polar ice cuases mixing of ocean water, which brings nutrients up from the ocean floor, population blooms and photosynthesis increases
  36. What are some ocean depth barriers for life?
    cold, pressure, salt concentration, lack of oxygen
  37. There's still an active community in the deep ocean depths, what percentage of all life on Earth lives down there? And where at the depths do they live?
    1/3, sediment at the bottom of the ocean
  38. What percent of infections are caused by contaminated water?
    80%
  39. How many deaths result worldwide each year from infections caused by contaminated water?
    2 million
  40. Who are most effected by water quality? Why?
    children under five - their immune systems aren't developed enough and they're more susceptible to dehydration and shocks that can occur due to diarrheal diseases
  41. What is the definition of coliform?
    facultatively anaerobic, gram negative, non endospore forming rod that ferment lactose to acid and gas within 48 hours at 37 degrees celsius
  42. What are some examples of coliforms?
    E. coli, Proteus, etc
  43. Where are most coliforms found? What does their presence in food/water mean?
    intestinal tracts of mammals; is has been contaminated with fecal material
  44. What kind of testing is used to detect contamination of food/water?
    coliform testing, it's the single most common test used to determine microbial quality of food/water
  45. Are coliforms pathogenic?
    no, many human pathogens live in the intestinal tract so if they are in water/food, then other microbes could be too
  46. What is eutrophication?
    a natural process of increased growth of organisms as bodies of water slowly become more nutritious over time
  47. What happens if nutrients in bodies of water increase too quickly?
    sudden increase in algal population may occur, when they die they release alot of nutrients and bacterial populations will suddenly increase, then sudden increase in bacterial metabolism depleted the water of oxygen and results in an oxy-gen deprived dead zone where fish and animals can't live
  48. What nutrients contribute most to europhication?
    nitrogen and phosphorus (low quantities in water which prevents rapid growth)
  49. How can humans contribute to eutrophication?
    fertilizer run-off and dumping sewage, they are rich in nitrogen and phosphorus
  50. How many continuous dead zones exist in the world? Where do they occur?
    more than 400, where coastal cities dump sewage into the ocean
  51. Where is the largest dead zone in the world?
    Where the Mississippi River runs into the Gulf of Mexico and covers more than 8,000 square miles
  52. What is bioremediation?
    use of microbes to degrade pollutants
  53. Where are bioremediations being used currently?
    oil spills
  54. How is bioremediation being used on oil spills?
    workers spray nitrogen, phosphorus, and other minerals (fertilizers) onto the spill area which encourages the growth of bacteria already present and they degrade petroleum hydrocarbons
  55. What species is especially good at bioremediation?
    Psuedomonas
  56. What is the goal of municipal water treatment?
    produce water free of pathogens
  57. What are the three steps required for water treatment?
    flocculation, filtration, and disinfection
  58. What is flocculation?
    raw water is mixed with a flocculant which binds to the contaminant in water (soil particles, clay, mineral, microbes) and forms clumps, water is transferred to a tank where the clumps of floc drop out of solution
  59. What is an example of a flocculant?
    alum
  60. What is filtration (water treatment)?
    water is passed through a filter of sand or crushed coal, which removes more contaminants (it's not a microbiological filter, but microbes will become trapped in passageways through sand)
  61. What microbe is usually filtered through filtration? Why is that good?
    Cysts of protozoa, they are difficult to kill with chlorine
  62. What is disinfection (water treatment)?
    water is disinfected by adding chlorine
  63. What is the ppm of chlorine?
    ~1ppm
  64. What is Arkadelphia's source of water?
    Ouachita River
  65. What are most microbes (like humans)? What does that mean?
    Chemoheterotrophs, the food we eat for carbon and energy aand other nutrients are also foods that microbes can use as carn and energy sources
  66. What must microbes be able to tolerate in food to use them as carbon sources?
    temperature, pH, osmotic pressure, and moisture content
  67. When is a food considered spoiled?
    when enough changes in taste, appearance, or smell of the food makes it unpalatable
  68. What are some causes of change in food?
    the natural ripening process of food; microbes: metabolic waste products of microbes (acids, ammonia), degradation of food caused by microbial exoenzymes, sliminess (biofilm production), visible microbial growth on food
  69. Most spoilage organisms are NOT what?
    pathogenic, they just make food distasteful
  70. What number of spoilage organisms must be present to change food (smell, taste, look)?
    10^6-10^7 per gram or mL
  71. What is the most common bacteria responsible for spoilage of milk and raw meat?
    Psuedomonas fragi
  72. Metabolically, what is Psuedomonas fragi?
    psychrotroph
  73. What are spoiled odors and flavors due to?
    metabolism of proteins and the production of ammonia, hydrogen sulfide, and other foul-smelling compounds
  74. A foodborne illness is not a foodborne illness if what?
    the food itself is poisonous (mushrooms, fish)
  75. What is a common foodborne illness? What is it caused by? What is it called? What are its symptoms?
    Gastroenteritis; numerous bacteria/viruses in food; "stomach flu", "food poisoning", "24 hour flu"; diarrhea, abdominal cramps, nausea, vomiting
  76. How is commercial sterilization achieved?
    steam under pressure in a retort
  77. What does commerical sterilization kill?
    endospores of clostridium botulinum
  78. Commercial sterilization is not a sterilizing treatment, what may survive in canning? Why does it not hurt us?
    endospores of thermophiles, they don't germinate because we store canned goods at room temp (which is too low for thermophiles to grow)
  79. Who developed modern pasteurization? What year? For what industry?
    Louis Pasteur, 1864, wine industry
  80. What is the target organism of milk?
    Coxiella burnetii
  81. What does Coxiella burnetii cause?
    Q fever, a respiratory infection
  82. What is traditional pasteurization time/temp? Where is this done?
    63 degrees celsius for 30 min; large vats
  83. Why is a popular time/temp combo for today's pasteurization processors? Why?
    72 degrees celsius for 15 sec; it's faster and the product never stops moving
  84. High temp, short time pasteurization is used on what common product?
    milk
  85. What is the time/temp combo for ultra high temp pasteurization?
    140 degrees celsius STEAM, 3 seconds
  86. Ultra pasteurization is also what kind of treatment?
    sterilizing treatment
  87. Which two pasteurizations are equally effective?
    traditional and high temperature, short time
  88. What is UHT used in the US to treat? Why?
    coffee creamer packets; since UHT treated foods are sterile they are shelf-stable (stored at room temperature without spoiling)
  89. What are some shelf-stable foods?
    canned foods, cereal, honey
  90. What is curlding caused by? What does this enzyme do?
    rennin, an enzyme that causes casein to coagulate
  91. How is cheesed produced?
    microbial cultures are mixed in with the curds, water is pressed out of teh curd, and mix is allowed to ripin in storage
  92. The more water that's pressed out of the curd, how does that effect the cheese?
    makes it harder
  93. What is an example of a cheese with lots of water pressed out?
    cheddar or especially parmesan
  94. The longer the fermentation of cheese what happens?
    it's more acidic or "sharper" tasting
  95. What is the most common bacteria to ripen cheese?
    Lactic acid bacteria (species of lactobacillus)
  96. What gives the different cheeses their different flavors and characteristics?
    the metabolic products produced by the bacteria in the cheese
  97. What is used to ripen Swiss Cheese?
    Propionibacterium fruendenreichii
  98. What causes the flavor of Swiss Cheese? What causes the holes?
    the propionic acid produced by the bacteria, the carbon dioxide produced
  99. What ripens many cheeses (like bleu cheese)?
    species of Penicillium in addition to lactic acid
  100. What bacteria causes the blue/green streaks in Bleu Cheese?
    Penicillim roqueforti growing from the surface down into the block
  101. How is yogurt produced?
    evaporated milk in inoculated with Streptococcus thermophilus and Lactobacillus bulgaricus and it's fermented for several hours at 45 degrees celsius
  102. Streptococcus thermophilus contributes to what in yogurt? What does Lactobacillus bulgaricus contribute to?
    acidifying the product, flavor and aroma
  103. S. thermophilus and L. bulgaricus must be used in the US in yogurt why?
    to have it legally labeled
  104. Products labeled as having "active cultures" had what happen?
    no pasteurization after prodcution, and still contain living bacterial cultures
  105. In bread production what does Saccharomyces cerevisiae do?
    metabolizes the sugars in the flour, producing carbon dioxide that creates the holes in the bread
  106. What happens to the alcohol made during fermentation of bread?
    it's evaporated out during baking
  107. What does kneading bread do?
    encourages aerobic respiration and imporves the gluten matrix
  108. Why is aerobic respiration preferred over fermentation of bread?
    the amount of carbon dioxide proudces per glucose is higher in aerobic respiration
  109. What is gluten?
    the main protein in bread that gives it a spongy feel
  110. What does gluten form in bread?
    a complex network in the dough that traps carbon dioxide
  111. What produces the acetic acid in vinegar?
    Acetobacter
  112. How is vinegar produced?
    first yeasts ferment carbohydrates to ethyl alcohol (like in beer or wine) then acetobacter is added to ferment the ethyl alcohol to acetic acid
  113. Vinegar is diluted to what percent of acetic acid?
    5%
  114. After vinegar is diluted, what is the process to get to the final product?
    filtered, pasteurized, and bottled
  115. What affects the taste and color of vinegar?
    it's original carbohydrates source
  116. Where does balsamic vinegar start?
    grapes
  117. Where does malt vinegar start?
    barley
  118. Where does white vinegar start?
    corn
  119. Which vinegar do we usually use and buy in stores?
    white vinegar
  120. What is the most common bacterium responsible for the spoilage of wine? Why?
    Acetobacter, it's ability to convert ethyl alcohol to acetic acid

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