Anaerobic bacteria are those bacteria that cannot survive in the presence of oxygen

Examples:

Clostridium, Propionibacterium and Actinomycetes etc.

Classification:

There are three types of anaerobic bacteria.

• Obligate anaerobes:

Obligate aerobes can’t survive in the presence of oxygen. They immediately die if oxygen is present in their environment. They don’t have catalase and superoxide dismutase enzymes that break the oxygen and superoxide radicles.

• Facultative anaerobes:

Facultative aerobes can survive in the presence of oxygen but can’t grow in the presence of oxygen. They stop their growth if oxygen is present in their surroundings. They have catalase enzyme that catalase the oxygen radicle. They don’t have superoxide dismutase enzyme that break the superoxide radicle and allow bacteria to grow.

• Aero tolerant:

Aero-tolerant is the bacteria that tolerate the presence of oxygen in their environment. They slow down their metabolism and allow themselves to tolerate the oxygen.

Why they don’t survive in the presence of oxygen?

When oxygen is utilized by bacteria, oxide and superoxide are produced. These radicles are lethal for bacteria. These radicles are catalyzed by catalase and superoxide dismutase enzyme. If the bacteria don’t have these enzymes, they can’t live in the presence of oxygen. Anaerobic bacteria don’t have these enzymes.

How these bacteria survive?

There are 2 pathways to survive

Fermentation:

These bacteria use fermentation to grow and survive in environment. They obtain their energy by fermenting glucose into lactic acid, alcohols and energy as a by-product.

C6H12O6 + 2 ADP + 2 phosphate → 2 lactic acid + 2 ATP

These bacteria are commercially very important as they can be used to produce acids, alcohols if grow in large amount

Other than oxygen:

Oxygen ion accepts the free electron in the end of electron transport chain. They used other ions such as sulfur, nitrogen to accept the free electron and grow.

How to create anaerobic condition in culture rooms?

There are many ways to create an-aerobiosis in culture room

• Use candle in the anaerobic jar. Candle utilizes all the oxygen present in the anaerobic jar and creates an oxygen free environment.
• Use palladium in the anaerobic jar. Palladium allows hydrogen to react with oxygen and produce water. In this way, oxygen removed from jar
• Use another gas e.g. nitrogen gas to grow the bacteria. Nitrogen creates an anaerobic condition and allow bacteria to grow.