The Role of Bacteria in the World

Aishwarya Addepalli & Sonja Feaster

Environmental Bacteria

- Of the thousands of bacteria that live on Earth, only a few hundred cause disease, like strep throat or a cavity in your tooth.

- Many bacteria do things that are important and even are helpful to us.

Nitrogen Fixation

-Most living things depend on plants.

-Plants need oxygen to grow.

-Nitrogen gas makes up 78% of the air, but plants can't take it directly from the air. They need to take in a different form of oxygen.

-Nitrogen-fixing bacteria take in nitrogen air and change it into a form that plants can use.


- Decomposer bacteria break down dead plant and animal matter, like in a gardener's compost pile.

- This makes nutrients available to other living things,

Cleaning up

-BIOREMEDIATION : using microorganisms to change harmful chemicals into harmless ones.

- Used to clean up hazardous waste from industries, farms, cities, and oil spills.

Bacteria in Food

-People raise bacteria for Food!

-Every time you eat cheese, yogurt, buttermilk, or sour cream, you are also eating bacteria.

-Lactic-acid producing bacteria break down sugar in milk (Lactose).

-Bacteria can change lactose into lactic acid, and this preserves and adds flavor to the food.

Making Medicines


-They are used to kill bacteria and other microorganisms.

-Many antibiotics are made by bacteria.


-It breaks down and uses sugar and carbohydrates.

-People with Diabetes do not make enough insulin.

-n 1970's, scientists discovered how to put genes into bacteria to produce human insulin (bacteria are separated from the insulin)

:( Harmful Bacteria

- In 1800s, scientists learned that some bacteria are pathogenic, which means "cause disease"

- Pathogenic bacteria get inside a host and take nutrients from the host's cells, harming the host in the process.

- We are protected from many bacterial diseases by vaccines and treated with antibiotics.

Diseases in other organisms

- Cause odd-colored spots and soft rot in leaves.

- Pathogenic bacteria attack plants, animals, protists, fungi and other bacteria.

- They can cause damage to fruit, grain, and vegetable crops.

- The disease in the picture show branch of a tree with bacterial disease called "fire blight".


The World of Bacteria: HRM (Human Relations Media)