This world is surround by trillions of types of bacteria; they are the most numerous of all organisms on this planet, and we come into contact with them on a daily basis. This large amount of bacteria species means that each is unique, with its own individual shapes, behaviors, and the environments in which they live.
- Shape. Scientists have determined that bacteria are not all shaped the same. Each species is broken down into one of three basic shapes, which in many cases determines their naming and even their behaviors. Bacteria that are spherical shaped are referred to as coccus bacteria, and the most common example would be streptococcus, the bacteria that causes strep-throat. For bacteria that are pill-shaped, they are known as bacillus. Typically, these are used as examples in textbooks and movies because they stand out from other spherical objects in the area and are the source of many human illnesses. The bacteria Bacillus anthraces is the pathogen that causes anthrax. The last shape bacteria fall under is spirillum, which include bacteria like Spirillum minus, the cause of rat-bite fever. These bacteria are coiled like a spring and are typically thin and elongated.
- Gram Postive and Gram Negative. A bacteria's danger to living organisms is usually based on the thickness of its plasma membrane. An organism's immune system is usually able to kill of bacteria by punching holes in its cytoplasm, killing it in the process. However, if the bacteria has a thick membrane, these immune cells can't damage them and this gives them the ability to multiply unhindered. Gram staining, the process in which dye is inserted into a medium full of bacteria, is used to determine the amount of peptidoglycan found in a bacteria's cell membrane. If the bacteria is Gram Positive, it has a thicker peptidoglycan wall and is more resistant to attacks on an organism's immune system; these are what cause illness. If it is Gram Negative, the bacteria has little peptidoglycan and is considerably weaker, making them easy targets by an individual's immune system.
- Aerobic Vs. Anaerobic. Bacteria are found in every nook on this planet. Being the first organisms on this planet, they evolved to endure environments that were anaerobic, or without oxygen. Over time, as oxygen increased, bacteria evolved to live in aerobic environments where they could utilize oxygen for cellular activities. For bacteria that are transmitted between people, such as strep throat, they are considered aerobic because they can survive temporarily outside a host. For the botulism bacteria, which can cause nerve damage in humans, oxygen is incredibly dangerous and can kill them in seconds.
- Cyanobacteria. Cyanobacteria are a peculiar species of bacteria because they represent the first known examples of organisms that were capable of photosynthesis; converting sunlight into usable cellular energy. These bacteria are autotrophic and are harmless to organisms because they do not require a host to obtain nutrients or to multiply. In fact, cyanobacteria are being used by scientists as a potential source of renewable energy due to their rapid reproduction rate and photosynthetic capability.
- Mutualistic Bacteria. Some bacteria have developed relationships with organisms where both achieve a positive outcome. In plants, nitrogen fixing bacteria are allowed to grow on the roots of various vegetables where they help increase the area of water absorption for a plant and are able to convert nitrogen in the atmosphere into ammonia, which is a required nutrient in plant soil. In humans, e. coli bacteria reside in the large intestine where they help produce Vitamin K, an essential clotting factor for the blood. In exchange, the bacteria absorbs waste products that pass through our intestines on the way out of the body.