The microscopic, single-celled organisms called ‘bacteria’ have been around for millions of years, even before mankind came into existence. But despite being the oldest life form, not everyone is aware of the innumerable types of bacteria present in this world and the various roles they play in maintaining harmony and balance in nature.
Did you know that there are more bacteria on your tongue than there are people in this world? Or that all the bacteria in your body collectively weigh about 4 pounds? From bread and yogurt to dirt and even inside animals and humans, bacteria are literally everywhere!
Here, we have gathered info on more than 16 major types of bacteria that can be found all around. Keep reading to learn more.
After all, these infinitesimally small creatures deserve a moment in the spotlight too.
Types of Bacteria According to Shapes
Before the advent of DNA sequencing, scientists classified bacteria according to their shapes and other biochemical properties. The following are the main types of bacteria based on different shapes.
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Coccus
Round-shaped bacteria
Bacillus
Rod-shaped bacteria
Vibrio
Comma-shaped bacteria
Spirochete or spirilla
A spiral or coil-shaped bacteria
Helicobacter
Helical bacteria
Types of Bacteria According to Cell Wall Composition
Bacteria are classified into two main types depending on the results obtained when a sample of bacteria is tested by the Gram Stain Method.
Gram-negative
This refers to bacteria that lose the crystal violet stain color in the Gram Test and gain a red color instead. This means they have a thin cell wall made up of a certain substance (i.e. lipopolysaccharide).
Gram-positive
This refers to bacteria that give positive test results, which means they have a thick cell wall that is made up of a protein called peptidoglycan.
Major Types of Bacteria
Actinobacteria
This phylum of thick-walled bacteria includes microorganisms that can be terrestrial as well as aquatic. Actinobacteria play a significant role in maintaining soil conditions and are, therefore, of huge importance in agriculture and forestry.
Their contributions to the soil system primarily include decomposing dead organic matter and regulating the amount of nitrogen in the soil so that plants can grow up healthy and strong. Actinobacteria are also found abundantly in freshwater bodies but most of their species are known to cause diseases in humans. However, Streptomyces, which is the largest genus of actinobacteria, is a major source of many antibiotics.
Aquificales
Aquificales are a further categorization of the class Aquificae. As you might have guessed from their name, Aquificalesare commonly found in ‘aquatic’ regions. They are a diverse collection of microorganisms that are well known for their ability to survive in harsh environmental conditions.
For example, Aquificalesthrive in volcanically or geothermally heated environments have temperatures that can reach close to boiling point or even higher. In pools, springs, lakes and even oceans, this type of bacteria is the primary contributors for fixing carbon in the surroundings.
Bacteroidetes
Bacteriodetes is a type of rod-shaped and gram-negative bacteria that can be either aerobic or anaerobic and can be found in the soil, sediments and in seawater. But don’t panic when we say that this type of bacteria might be present inside your body at this very moment.
Yes, you read that right. Bacteriodetesoften lives in the guts as well as on the skin of humans and several other animals where they serve specific roles. But the bad news is that most of them aren’t really good for your health.
For instance, some bacteroidetes lead to an imbalance of short fatty acids in your body while some can lead to the production of other toxins. Worse scenarios may also include neurological disorders. Plus, they are quite resistant to antibiotics mechanisms.
Chlamydiales
Chlamydiales live in animals, insects, and protozoa. They are obligate intracellular bacteria meaning that they are able to survive or exist only in a particular environment or by assuming a particular role. The common Chlamydia bacterial infection consists of these microorganisms.
Cyanobacteria
This type of bacteria is also called Cyanophyta or blue-green bacteria because of their appearance when viewed under a microscope. Hence, the term ‘cyan.’
Cyanobacteria survive by obtaining their energy through photosynthesis and are the only prokaryotes that possess the ability to produce oxygen on their own. This gas is synthesized in flattened sacs called thylakoids.
An interesting fact about cyanobacteria is that they are believed to have led to the Great Oxygenation Event that changed the composition of the earth’s atmosphere and almost led to the extinction of all anaerobic life forms.
Deinoccus-Thermus
