Chapter 7
Bacteria

What are bacteria?
• Bacteria are microscopic, living cells.
– live almost everywhere, even extreme environments
– sphere-shaped, rod-shaped, spiral-shaped
• smaller than plant or animal cells
• prokaryotic-no membrane-bound internal structures

What are bacteria?
– some have a capsule around the cell wall while others have an outer slime layer
– many have whiplike tails called flagella
– most reproduce by fission

What are bacteria?
– can be producers or consumers
• most are aerobes
• some are anaerobes

What are bacteria?
• Bacteria are classified into two kingdoms.
– Eubacteria larger of the two bacteria kingdoms
• consumer eubacteria are grouped by cell wall thickness
• cyanobacteria produce their own food and are commonly called blue-green bacteria
• cyanobacteria provide food and oxygen for aquatic life
– bloom- may be harmful

What are bacteria?
• Bacteria are classified into two kingdoms.
– Archaebacteria
• kingdom bacteria are often found in extreme locations and divided into groups based on where they live or how they get energy
– some live in salty, acidic, or very hot environments
– one anaerobic group produces methane gas

Bacteria in Your Life
• Most bacteria are helpful rather than harmful
– necessary for human health
• many aid digestion and some produce vitamins
• some produce antibiotics

Bacteria in Your Life
• Bacteria help keep nature in balance
– bacterial saprophytes use dead organisms as food and energy sources
– nitrogen-fixing bacteria in the soil and plant roots change nitrogen from the air to a form that plants and animals can use

Bacteria in Your Life
• Bacteria can be used to clean up the environmental pollution through bioremediation
– some bacteria break waste down into harmless compounds
– certain bacteria can eat pollutants

Bacteria in Your Life
• Many foods are made using bacteria
– used in dairy products
– sauerkraut and pickles are also among foods made with bacterial help

Bacteria in Your Life
• Bacteria are used in industry
– bioreactors- large, carefully controlled containers used to make medicines and many other products
– methane-producing bacteria can digest waste and provide a source of fuel

Bacteria in Your Life
• Bacteria that cause disease are called bacterial pathogens
– toxins are made by some bacterial pathogens
– some form thick walled structures called endospores when environmental conditions are unfavorable

Bacteria in Your Life
– pasteurization- process of limited heating, can kill most harmful bacteria in food
– vaccines can prevent some bacterial infections
• made from damaged or dead bacterial cells
• enable white blood cells in the body to recognize a particular type of bacteria and attack it if it appears at a later time