1 / 36

Announcements

Announcements. Instagram account for the lab: vuubio201 Lab 3 handout-take 1 before you leave class DO THE PRE-LAB and READ THE ENTIRE DOCUMENT BEFORE you take the quiz Quiz due at midnight Wednesday 2/5 As you are doing the lab, READ DIRECTIONS CAREFULLY Late lab notebook 5 points off

salma
Télécharger la présentation

Announcements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Announcements Instagram account for the lab: vuubio201 Lab 3 handout-take 1 before you leave class DO THE PRE-LAB and READ THE ENTIRE DOCUMENT BEFORE you take the quiz Quiz due at midnight Wednesday 2/5 As you are doing the lab, READ DIRECTIONS CAREFULLY Late lab notebook 5 points off Lab notebook due Monday 2/10

  2. Chapter 4: Dynamics of Prokaryotic Growth, Part 2

  3. 2 Minute Brainstorm and Recap What are the environmental factors that influence microbial growth? Did you know that there are also nutritional requirements also for microbial growth?

  4. Why do bacteria need specific nutrients? What are their monomers? What are the four major macromolecules of life? • Carbohydrates • Proteins • Lipids • Nucleic acids • Monosaccharide • Amino acid • Fatty acids • Nucleotides Bacteria require the major elements to make these macromolecules!

  5. Required Elements That Make Up Bacterial Cell Parts phosphorus 15 magnesium 12 potassium 19 hydrogen 1 nitrogen 7 calcium 20 carbon 6 sulfur 16 iron 26 oxygen 8 Mg Ca Fe S H K P C N O 32.065 14.007 12.011 30.974 39.098 24.305 40.078 55.845 1.008 15.999

  6. Lipids Sugars Amino Acids Amino Acids: Cysteine Nucleic Acids

  7. Enzymes:

  8. Oops…Out of Stock! • Have you ever been baking cookies and realized you have only half the amount of a certain ingredient? That specific ingredient (let’s say chocolate chips) is the limiting nutrient • The number of cookies you make DEPENDS on the amount of chocolate chips • Bacteria have limiting nutrients also phosphorus 15 iron 26 Fe P 30.974 55.845 Determines the maximum level of microbial growth possible- All bacteria need it, but there is not enough to go around.

  9. Too Much of A Limiting Nutrient=Explosive Growth! How do you control the growth then? Remove Phosphorus Problems with pollution in water (extra phosphorus) allows for algae to grow out of control!

  10. What is the source of carbon for bacteria? • Autotroph • Auto = self • Use inorganic carbon from CO2 What is the energy source for bacteria? • Phototroph • Photo = sunlight • Extract energy from the sun • Chemotroph • Chemo = chemical • Extract energy from chemical compounds • Heterotroph • Hetero = different • troph = nourishment • Uses organic carbon

  11. Where do these different bacteria get their energy and carbon from? CO2 CO2 Organic compounds lith = Stone- Inorganic CO2 Organic compounds organo= organic

  12. To learn how bacteria can be used for our benefit or treated with drugs in infections, we need to be able to grow and study them in the lab…

  13. Recreating Bacteria Growth Requirements in the Lab • 2 types of media: • Liquid media- water-based broth containing nutrients (example: LB broth) • Solid media- broth with agar added that turns into a gelatinous solid when cooled to room temperature (example: agar plates)

  14. Why Use Agar? • Polysaccharide extracted from marine algae • Microbes can not degrade it • Not destroyed at high temperatures • Can be autoclaved to sterilize • Solidifies below 45oC • Add in heat sensitive nutrients • Once solidified, remains that way until heated to 95oC • Covers the temperature range of microbial growth

  15. We Have An Agar Plate with Bacteria Pictured Below…Now What? Colony- a distinct mass of cells -contains at least one million bacterial cells to be visible -colony started from one single bacterium (clonal)

  16. No longer dividing Still dividing/expanding

  17. How do I study only the blue colonies?

  18. Colony selection Aseptic technique

  19. Streaking for isolation

  20. Streaking for isolation

  21. Streaking for isolation

  22. Streaking for isolation

  23. Streaking for isolation

  24. Isolated colonies Using an isolated colony, you can start a pure culture -a population descended from one single cell (clonal) -contains only one species

  25. Growing Bacteria in the Lab: Most Can Eat A Good Meal Like Us! • Complex media- variety of ingredients in varying amounts (you never know the exact composition), “tasty soup” Example- Nutrient agar Grows most types of bacteria General lab use; easy to make Example- Blood agar Grows most types of bacteria General lab use

  26. Growing Bacteria in the Lab: But, Some Need Specific Meals! • Chemically defined media- uses exact amounts of pure chemicals • Used in experiments where nutrition is strictly controlled or for “picky” bacteria • Example: Neisseria gonorrhoeae • Require very specific nutrients to grow (46 total!)

  27. Comparison Between Complex and Chemically Defined Media Nutrient broth Glucose salts broth Complex Chemically Defined Peptone Meat extract Water Glucose Dipotassium phosphate Monopotassiumphosophate Magnesium sulfate Ammonium sulfate Calcium chloride Iron sulfate Water

  28. Activity: Selective Media • We are a mixed population of bacteria: stand up • If you have a red paper: eat peanuts for your diet to grow • If you have a blue paper: eating peanuts will inhibit your growth • We feed both bacteria crushed up peanuts with agar on the same plate: if you grow stay standing. If you don’t, sit down. Who lives? • This is a selective media RED

  29. Selective Media • Selective media- inhibits the growth of certain species, while allowing the growth of others MacConkey agar is selective, because only Gram negative bacteria can grow on it (inhibits Gram positive bacteria from growing)

  30. Activity: Differential Media • We are a mixed population of bacteria: Stand up • If you have a red paper: you produce a protein which kills red blood cells and turns them white • If you have a blue paper: you produce a protein which partially kills red blood cells and turns them green • We feed both bacteria red blood cells with agar (blood agar) on the same plate: does everyone grow? • How can you tell the difference between the bacteria? • This is a differential media AND REALLY HAPPENS with Bacteria! • Partial lysis of red blood cells: Green • Full lysis of red blood cells: White YES White vs. Green colors

  31. Differential Media • Differential media- does not inhibit microbes, but it allows you to differentiate species with color changes MacConkey agar is both selective and differential; it inhibits growth of Gram positives, and indicates which Gram negatives can ferment lactose with a color change

  32. Question Hektoen enteric agar- -contains inhibitors to prevent Gram positive growth -If the bacteria produce H2S, the colony appears black -If the bacteria can ferment the sugars in the media, it turns yellow/orange Is it differential? Selective? Both?

  33. How Do Bacteria Grow In Nature? BIOFILMS • Bacteria that attach to a surface and live as a community encased in polymer “slime”

  34. Biofilm Planktonic bacteria (motile) Biofiolm bacteria (immobile) Secrete extracellular polymeric substances (EPS) Protected!

  35. Bad Biofilms Contaminate/damage surfaces of industrial machinery Infections from biofilms on catheters Dental plaque that leads to tooth decay

  36. Good Biofilms

More Related