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Bacteria: the good, the bad and the ugly


Title: Type III Secretion Systems Author: Finlay Lab Last modified by: FNH AGSCI Created Date: 11/15/1999 7:06:36 PM Document presentation format – PowerPoint PPT presentation

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Title: Bacteria: the good, the bad and the ugly

Bacteria the good, the bad and the ugly
  • Anne Todgham and Annick Gauthier
  • University of British Columbia

What are bacteria?
  • Small organisms - several µm (1/1000 of a cm, can
    only see 1/100)
  • They have all they need to live
  • DNA
  • Energy
  • Food
  • Can make proteins
  • Good and bad bacteria!!!!!!
  • Bacteria can be killed with antibiotics
  • Viruses are different - need host to live
  • Cant kill virus with antibiotics

Rod-like Bacteria
Pictures of Bacteria
Bacteria from Fish
Where are bacteria?
  • On our skin
  • In our intestinal tract
  • Help us digest food
  • In our mouth, throat
  • In the soil
  • In the ocean
  • In the forest
  • On plants
  • Everywhere!

Good vs Bad
  • Some bacteria cause disease
  • meningitis
  • pneumoniae
  • diarrhea
  • Good bacteria too for example E. coli
  • there are disease-causing strains
  • there are digestion-helping strains

Why we should love bacteria
  • Live happily in the guts and lungs of animals
  • aid in digestion of food and vitamin production
  • stimulate the growth of some of our tissues
  • Fight foreign disease causing bacteria and
    prevent them from infecting us
  • Important in the cycling of nutrients in the
    environment ex. nitrogen and carbon
  • Make up the bottom of most food webs
  • critical for the survival of most living
  • thought to be the origin of multicellular

Why bacteria love us
Our bodies provide bacteria with
  • Constant supply of nutrients
  • Stable environment and constant temperature
  • Protection
  • Transportation

We are a great home to live in!!
Interesting tidbits
  • 1013 bacteria in/on human body, and only 1012
    human cells
  • 109 bacteria per gram of feces (population of
  • Only a very small number of bad bacteria
  • We breathe in 3-4 bacteria per breath
  • Number one infection cavities
  • 50 of worlds population dies of infectious
    diseases (20 in our society)
  • Infectious diseases are the leading cause for
    taking time off of work
  • More people died in the Civil War of infectious
    disease that by bullets.

More cool bacteria numbers
  • Oldest fossil known is bacteria-like organisms
    that are 3.5 billion years old!!
  • 100 000 bacteria in each cm2 of skin
  • 1 billion bacteria in a teaspoon of soil
  • 80 distinguishable species of bacteria living in
    the mouth alone
  • Greater than 200 species of bacteria living on
    the entire body
  • Can reproduce every 20 min

Uses for Bacteria
  • Production of antibiotics like streptomycin and
  • Put the tang in yogurt and the sour in sour cream
  • Vaccination (dead or weak bugs used to boost our
    immune system)
  • Can be used to break down oil after an oil spill

Growing Bacteria
  • All the bacteria that we will grow are normal
    bacteria that do not cause disease
  • Bacteria grow in colonies on a substance called
    agar that contains sugars and salts
  • We have poured these agar plates for you
  • Incubate plates at 37oC at UBC for 2 days
  • Plates will be stored in fridge until October 23
    when we will return to discuss results with you

Materials and Methods
  • Objective to culture bacteria from around the
    classroom and your body
  • Materials 1 LB agar plate, 4 cotton swabs,
    pencil and paper to take notes, marker
  • Method
  • 1. Using black marker, divide plate into 4
    quadrants, label plate with your name and the
    date in small letters
  • 2. Choose which 4 areas you will swab and record
    this in your science duotang
  • 3. Label the plate with the areas you will swab
  • note label the bottom (i.e. agar containing part
    of the plate)
  • 4. Remove one sterile swab from its packaging (do
    not touch it), swab area of choice by gently
    rubbing cotton swab on it, and then transferring
    this to the LB agar plate by gently rubbing the
    agar in the designated quadrant
  • 5. Repeat step 4 for 3 other areas of choice
  • 6. Clean up put LB plate and marker into middle
    of your table, put all cotton swabs and wrappers
    into orange garbage bag

Pictorial of Procedure
Next class
Growing Bacteria
  • thumb
  • mouth, nose or ear
  • floor
  • table
  • phone
  • keyboard
  • light switch
  • sink
  • sink faucet
  • toilet handle
  • toilet

Culturing Bacteria
(No Transcript)
Identification of Bacteria
  • Grow bacteria on different media
  • Different bacteria grow on different types of
  • Check for antibiotic resistance
  • Jessicas expt
  • Use stains or antibodies
  • Gram stain
  • Antibodies agglutinate
  • Clump up bacteria
  • DNA
  • amplify certain genes

How do we defend ourselves?
  • Non-specific
  • Skin
  • Hair
  • Shedding cells
  • Tears
  • Macrophages
  • Good bacteria!
  • Specific
  • Antibodies
  • B cells
  • T cells

Picture of Gastrointestinal Tract
Bacteria of the mouth
  • Dental plaque, cavities and periodontal disease
    result from the actions initiated by our normal
    bacterial flora
  • 60-70 of the volume of plaque is made of
    bacteria -- these bacteria release lactic acid
    that breaks down the enamel of the teeth and can
    cause cavities and further infection of your mouth

Picture of Respiratory System
Life without bacteria
  • Normal bacterial flora are very important in
    protecting our bodies from pathogenic or
    disease-causing bacteria
  • Administration of broad-spectrum antibiotics has
    a profound effect on our good bacteria and can
    result in bad antibiotic-resistant bacteria
    infecting our bodies
  • Animals raised in an environment filled with
    bacteria are much healthier than those raised in
    a sterile environment
  • Clean hypothesis
  • People need bacteria to live

How can we stay healthy?
  • Good nutrition
  • Low stress
  • Age
  • Cleanliness
  • but we need bacteria
  • antibacterial soaps
  • Regular doctor and dental visits
  • Vaccines up to date