Bacteria are amongst the smallest living things in the world, containing just one cell. Bacteria are single-celled or unicellular organisms. Bacteria are so small that we need a microscope to see them. Bacteria are everywhere: in the air, our skin, the ground, bodies, and nature.
Bacteria are microorganisms that need nutrition from their environment. Many types come in various shapes and sizes, including spheres, spirals, and rods. Some can swim, some can glide, and others stay still for a long time.
Most bacteria are not dangerous, though some kinds of bacteria can make us sick. Bacteria that make us unhappy are called pathogens. Pathogens can cause diseases in many living things, including animals and plants. Our bodies can fight off pathogens with our immune system, but we can get sick. We can prevent pathogens from entering our bodies by washing our hands.
Although bacteria are just a single cell, they can carry out all six life processes:
- movement;
- respiration;
- sensitivity;
- growth;
- excretion;
- nutrition.
Keep reading to learn some fun bacteria facts!
The three different types of bacteria
Although there are many different types of bacteria living around the world, there are five most common types of bacteria that are distinguished by their shape and the structure of their wall, which include:
- Spirochaetes: These corkscrew-shaped bacteria fall into three types (Treponema, Leptospira, and Borrelia) and can cause specific diseases.
- Rickettsia: These are bacteria from the Rickettsiaceae family, which can only live and survive inside other living cells.
- Mycoplasma: These are bacteria that have no cell wall. These can infect humans and cause.
- Cocci: These are spherical cells with thick cell walls and are termed gram-positive because they take up the Gram stain. Those with thin cell walls are termed gram-negative.
- Bacilli: This is a rod-shaped bacterium that includes two orders, Bacillales, and Lactobacillales, which contain several well-known pathogens such as Bacillus anthracis and are almost exclusively gram-positive bacteria.
Shapes of bacteria
Bacteria come in a range of different shapes and sizes. Certain types of bacteria are rounder, while others are shaped like rods, and some have an unusual shape. Generally speaking, there are three main shapes of bacteria:
- Coccus: A round shape
- Bacillus: A rod shape
- Spiral: A spiral or twisted shape
Common bacterial cell arrangements
In addition to the different shapes of bacteria, there is a range of different types of bacteria cell arrangements. The common types of bacterial cell arrangements are as follows:
- Diplo: In this arrangement, the cells stay in pairs after dividing.
- Strepto: In this arrangement, the cells remain in chains after splitting.
- Tetrad: In this arrangement, the cells stay in groups of four and divide into two planes.
- Sarcinae: In this arrangement, cells remain in groups of eight and divide into three planes.
- Staphylo: In this arrangement, cells stay in clusters and split into multiple planes.
These are all the standard arrangements and shapes of bacteria, but there are several exceptions. The more unusually shaped bacteria are known as pleomorphic and will experience different forms at different stages in their life cycles.
Cocci bacteria
One of the three main shapes of bacteria is the coccus bacteria. Coccus bacteria, the plural for which is cocci, have a round, oval, or spherical shape. There are a few different arrangements that these bacteria can take on:
- Diplococci: In this arrangement, cells stay in pairs after dividing.
- Streptococci: In this arrangement, cells remain in chains after splitting.
- Tetrad: In this arrangement, cells stay in groups of four and are divided into two planes.
- Sarcinae: In this arrangement, cells remain in groups of eight and divide into three planes.
- Staphylococci: In this arrangement, cells stay in clusters and split into multiple planes.
Types of cocci
There are a few different types of coccus bacteria, all of which are named based on their bacterial cell arrangement. The kinds of coccus bacteria include Diplococcus bacteria, Streptococcus bacteria, Staphylococcus bacteria, and Enterococcus bacteria.
Bacilli bacteria
The next of the three main shapes of bacteria is bacillus. Bacillus bacteria, the plural of which is bacilli, are rod-shaped bacteria cells. There are several different arrangements that bacillus cells can take on:
- Monobacillus: In this arrangement, cells stay as singular rod-shaped cells after dividing.
- Diplobacilli: In this arrangement, cells stay in pairs after dividing.
- Streptobacilli: In this arrangement, cells stay in chains after dividing.
- Palisades: In this arrangement, cells in a chain are organized side-by-side instead of end-to-end. These cells are also partially attached.
- Coccobacillus: In this arrangement, cells are short with a slightly oval shape. These cells look like coccus and bacillus bacteria.
Types of bacilli
There are several types of bacillus bacteria, all of which have slightly different functions. Bacillus bacteria can be found in various environments, including the soil and the ocean. This type of bacteria is also located within the human body, wherein they help the process of digestion and boost immune health. Bacillus bacteria are also used to make different types of food and drink, including wine, cheese, yogurt, and beer.
Spirilla bacteria
The last of the three main shapes of bacteria are spirilla bacteria. Spirilla bacteria have a spiraled, twisted shape and typically occur in three forms: spirillum, the plural of spirilla, spirochaetes, and vibrio. Let’s have a look at each of these forms of bacteria:
- Spirilla
Spirilla bacteria have a long spiral shape and are rigid cells. It is also likely that these cells have flagella, which are lengthy projections at each end of the cell used for movement.
- Spirochaetes Bacteria
Spirochaetes bacteria are long, tightly-coiled cells that are spiral. One difference between spirochaetes and spirilla bacteria is that, while spirilla are super rigid, spirochaetes are much more flexible.
- Vibrio Bacteria
While vibrio bacteria are fairly similar to spiral bacteria in shape, there are a few key differences. Vibrio bacteria have a slight curve to them, identical to a comma. Like some spirilla cells, this type of bacteria also has flagella, which are projections for movement. Many types of vibrio bacteria are known as ‘pathogens,’ organisms that cause disease. They are heavily associated with food poisoning and can also infect open wounds to cause blood poisoning.
This bacterium is known as ‘facultative anaerobes,’ meaning they can survive without oxygen.
How to prevent bacteria
Although not all bacteria are bad, the easiest way to clean away bacteria is by washing your hands! Handwashing is one of the easiest ways to protect yourself and others from illnesses like flu and food poisoning, and it is easy to promote and teach in schools to develop effective and safe hygiene standards. There are many resources available on the Twinkl site that can teach pupils how and why they should be washing their hands in different scenarios, such as:
- when your hands are dirty;
- before eating or touching food;
- after using the bathroom;
- after blowing your nose or coughing;
- after touching pets or other animals;
- after playing outside;
- before and after visiting a sick relative or friend.
Fascinating bacteria facts
Learn all about bacteria with this list of fun bacteria facts!
- Did you know that bacteria is the oldest known life form on Earth? Yep, scientific studies have found that bacteria have been around for more than 3.5 billion years, which is longer than any other life form on the planet.
- Something that people never really consider when talking about bacteria is their speed. On average, a single bacterium can move around 100 times its body length in just one second, making them super speedy life forms.
- All yogurt lovers out there are eating bacteria with your favorite snack. Many common foods, such as yogurt, cheese, and kimchi, are all made using bacteria. Don’t worry; it’s completely safe! The bacteria used to make these kinds of foods are beneficial for your gut health.
- Leading on from that last bacteria fact, there is a common misconception that bacteria are bad for you when, in fact, most bacteria are good. The human body has way more bacterial cells than human cells. The human body is around 90% bacteria. Bacteria are useful for digestion and help the body fight off bad bacteria. Shockingly, only 1% of all the bacteria in the world will make us sick.
- Bacteria have existed for billions of years but were only discovered in 1674. A Dutch scientist named Antonie van Leeuwenhoek was responsible for their discovery. Van Leeuwenhoek was looking at scrapings from the human mouth under the microscope, a device that had only just been invented, when he spotted bacteria for the first time.
- Bacteria are extremely adaptable, which works against us when trying to cure bacterial illnesses. For example, antibiotics are used to fight off bacteria within the body. Still, it is hard to find an antibiotic that is consistently effective because bacteria can adapt quickly. For instance, if you take an antibiotic too often, the bacteria in your body resist it, and the drug becomes ineffective.
- Bacteria are single-celled organisms. This means they are made up of just one cell.
- Despite being little tiny organisms, bacteria are incredibly durable. Bacteria can survive many intense conditions, including extreme heat, cold, and even radioactive waste. Not only can bacteria survive in these crazy conditions, but they thrive in them!
- Last up on this list of bacteria facts is that most bacteria haven’t been identified yet. For instance, when a geneticist named J. Craig Venter analyzed the high seas water in 2003, he found over a million bacterial genes that had never been seen before.
How do bacteria benefit us?
Bacteria in the soil
Bacteria can benefit us in many ways, notably through their work in the soil. For example, a specific type of bacteria called decomposers can be found in soil, breaking down material from dead animal and plant matter. This fairly gruesome process is crucial for creating ground and removing dead tissue. Another handy type of bacteria found in soil is called Rhizobium. Rhizobium bacteria help fertilize the soil using nitrogen, which plants then use for growing.
Bacteria in food
You didn’t read that wrong; bacteria are in our food. Bacteria are used to make lots of different types of food, with yogurt being the prime example. Foods created using bacteria include pickles, cheese, vinegar, soy sauce, fermented fish, meat, and vegetables.
Bacteria in our bodies
There are tons of bacteria within the human body, all of which have various uses. One of the main uses of bacteria within the body involves the digestive system, as they help break down our food. In addition, some bacteria in the body are beneficial for fighting illnesses and keeping us healthy. These bacteria work with our immune system to help fight off different organisms that could make us sick.
Structure of bacteria cells
The structure of every cell type is unique. What sets bacteria cells apart from plant and animal cells is that they are prokaryotes, meaning they do not contain a nucleus.
Some of the elements that can be found in the majority of bacteria cells are;
- Capsule: Certain bacteria contain a tablet, a layer of protective covering located outside the cell wall. A pill is made up of complex carbohydrates.
- Cell wall: The cell wall is a rigid structure made of peptidoglycan, a protein-sugar molecule. The cell wall gives the bacterium its shape, and its role is to surround the cytoplasmic membrane and protect it from the environment. Depending on the species of bacteria, the cell wall can vary in thickness.
- Plasma membrane: The plasma membrane is located within the cell wall, generating energy and transporting chemicals. Moreover, the plasma membrane is permeable, meaning substances can easily pass through it.
- Cytoplasm: The cytoplasm is a jelly-like substance found inside the plasma membrane. This part of the cell is composed of water, enzymes, nutrients, wastes, and gases. Within the cytoplasm, there is a range of genetic material and ribosomes. The cytoplasm of bacteria cells is super important as cell growth, metabolism, and replication are all carried out.
- DNA: DNA, which stands for deoxyribonucleic acid, is a polymer that contains all of the genetic instructions necessary for the development and growth of bacteria. This part of the bacteria cell is located within the cytoplasm.
- Ribosomes: Ribosomes are teeny tiny particles in bacteria cells responsible for making proteins.
- Flagellum: The flagellum is important in the bacteria cell, as it is used for movement. Depending on the species of bacteria, there can be more than one flagellum. Flagella (the plural of flagellum) are very fine, hair-like structures that propel the bacteria forward in a propeller-like motion. This movement is necessary because it takes the bacteria away from toxic chemicals and towards nutrients.
- Pili: Pili are present in some, but not all, bacteria cells. They are hair-like structures that protrude from the outside of the cell. They allow bacteria cells to adhere to surfaces and transfer genetic material to other cells.
