Bacteria's role in our world

1. Bacteria’s Role in Our Bacteria’s Role in Our
WorldWorld

2. Good For the EnvironmentGood For the Environment
Of the thousands of Of the thousands of
bacteria that live on bacteria that live on
Earth, only a few Earth, only a few
hundred cause hundred cause
disease, like strep disease, like strep
throat or a throat or a cavitycavity in in
your toothyour tooth
Many bacteria do Many bacteria do
things that are things that are
important and even important and even
helpful to ushelpful to us

3. Nitrogen FixationNitrogen Fixation
Most living things depend on plantsMost living things depend on plants
Plants need nitrogen to growPlants need nitrogen to grow
Nitrogen gas makes up Nitrogen gas makes up 78%78% of the air, but of the air, but
plants can’t take it directly from the airplants can’t take it directly from the air
They need to take in a different form of They need to take in a different form of
nitrogennitrogen
Nitrogen-fixing bacteria take in nitrogen from Nitrogen-fixing bacteria take in nitrogen from
air air and change it into form that plants can and change it into form that plants can
useuse

5. RecyclingRecycling
Decomposer Decomposer
bacteria break bacteria break
down down deaddead plant plant
and animal matter, and animal matter,
like in a gardener’s like in a gardener’s
compost pilecompost pile
This makes This makes
nutrients available nutrients available
to other living to other living
thingsthings

6. Cleaning UpCleaning Up
BioremediationBioremediation: using microorganisms to : using microorganisms to
change harmful chemicals into change harmful chemicals into harmlessharmless
onesones
Used to clean up hazardous waste from Used to clean up hazardous waste from
industries, farms, cities, and industries, farms, cities, and oil spillsoil spills

7. Bacteria in Your FoodBacteria in Your Food
People raise bacteria for People raise bacteria for
food!food!
Every time you eat cheese, Every time you eat cheese,
yogurt, buttermilk, or sour yogurt, buttermilk, or sour
cream, you are also eating cream, you are also eating
bacteriabacteria
Lactic-acid producing bacteria Lactic-acid producing bacteria
break down sugar in milk break down sugar in milk
(lactose)(lactose)
Bacteria change lactose Bacteria change lactose
into into lactic acidlactic acid
This preserves and adds This preserves and adds
flavor to the foodflavor to the food

8. Making MedicinesMaking Medicines
AntibioticsAntibiotics
Used to kill bacteria and other Used to kill bacteria and other
microorganismsmicroorganisms
Many antibiotics made by Many antibiotics made by bacteriabacteria
InsulinInsulin
Insulin breaks down and uses sugar and Insulin breaks down and uses sugar and
carbohydratescarbohydrates
People with People with diabetesdiabetes do not make enough do not make enough
insulininsulin
In In 1970’s,1970’s, scientists discovered how to put scientists discovered how to put
genes into bacteria to produce human insulin genes into bacteria to produce human insulin
(bacteria are separated from the insulin)(bacteria are separated from the insulin)

9. Harmful BacteriaHarmful Bacteria
In 1800s, scientists In 1800s, scientists
learned that some bacteria learned that some bacteria
are are pathogenicpathogenic, which , which
means “means “cause diseasecause disease””
Pathogenic bacteriaPathogenic bacteria get get
inside a host and take inside a host and take
nutrients from the host’s nutrients from the host’s
cells, harming the host in cells, harming the host in
the processthe process
We are protected from We are protected from
many bacterial diseases many bacterial diseases
by by vaccinesvaccines and treated and treated
with antibioticswith antibiotics

10. Diseases in Other OrganismsDiseases in Other Organisms
Have you ever seen a plant with odd-colored spots Have you ever seen a plant with odd-colored spots
or soft rot? It was probably damaged by bacteriaor soft rot? It was probably damaged by bacteria
Pathogenic bacteria attackPathogenic bacteria attack plants plants, animals, , animals,
protists, protists, fungifungi, and even other bacteria, and even other bacteria
They can cause damage to grain, fruit, and They can cause damage to grain, fruit, and
vegetable cropsvegetable crops
Branch of tree with bacterial
disease called “fire blight”