Bacteria (or the singular bacterium) are microscopic organisms made up of only one cell, and were among the first types of organisms to appear on the Earth. It has been suggested that bacteria could be found on the earth about 3.5 billion years ago. They were unknown to us until Antony van Leeuwenhoek first observed them in his microscope in the 1600s.
Bacteria can be found almost anywhere on earth, including in seas and rivers, deep in the ocean, in the soil, and in the tissues of animals.
Bacteria are very small. Even though there are 2.5 billion bacteria in one gram of soil, you will never see a single bacterium unless you have access to a powerful microscope. Even if you lined 10,000 bacteria up, side-by-side, it would only make up 2.5 centimeters of space.
There are many different types of bacteria – about 2000 species have been identified, and there are likely many more that are still unidentified.
Some bacteria are rod-shaped (bacilli), some are round (cocci) and some are spiral-shaped (spirilli). Some need oxygen to live (aerobic), while others do not (anaerobic). Some absorb their food from their hosts, while others made their own foods using photosynthesis (sunlight, carbon dioxide and water) or chemosysnthesis (carbon dioxide, water and certain chemicals).
These differences along with a ‘Gram Staining Method’ where some types will bind with a stain while others do not are used in order to identify different types of bacteria.
Bacteria and Illness
Most bacteria are harmless to humans, but bacteria are responsible for the cause of many types of illnesses. These illnesses range in severity from simple dental cavities to strep throat and also include deadly diseases such as cholera and anthrax. The bacterium Yersinia Pestis is thought to have been the cause of the Bubonic Plague or Black Death, one of the most devastating pandemics in history, which killed an estimated 30 to 60% of the population of Europe in the mid 1300’s.
The bubonic plague still occurs in some parts of the world, but does not cause the type of mass epidemic it once could because it’s treatable with antibiotics. Today, when you are sick from any bacterial infection, your doctor will likely prescribe antibiotics to help kill the bacteria.
The Beneficial Effects of Bacteria
Bacteria also have many positive effects such as releasing nitrogen to plants, decomposing organic materials and making yogurt and cheese.
Yogurt for example is made from milk with the help of a bacterium called Lactobacillus acidophilus, which turns milk’s natural sugars into lactic acid and contributes to yogurt’s tangy taste. Good bacteria from the Lactococcus, Lactobacillus, or Streptococcus families ferment milk into lactic acid when making cheeses, and also contribute to the final taste.
Water can be purified using certain types of bacteria, and there is a type of bacteria that eats oil, helping clean up oil spills. The largest oil spill in US history occurred from an explosion at the Deepwater Horizon rig on April 20, 2010. Just a month after the spill, a team of American scientists showed that a microscopic clean-up crew composed of 16 groups of bacteria, particularly the Oceanospirillales group, had already started to digest the mess.
And, of course, there is the type of bacteria that helps make up the flora of the human gut. While beneficial flora resides everywhere in the human body, it is the bacteria in your gut that may be the most beneficial of all.
Lactobacilli is a part of the small intestine’s flora, which is a type of bacteria that produces lactic acid. They are ‘probiotic’ since they are a positive or supportive microorganism and are one of the most important types of friendly bacteria found in the digestive tract. Lactobacilli is found in the large intestine as well, but Bifidobacterium bifidum is the main type of probiotic here. Not only do they help us digest food, possibly the most important job these beneficial bacteria have is to protect us from infection and to boost our immune systems.
Wikepedia – Black Death. http://en.wikipedia.org/wiki/Black_Death
Probiotic -Intestinal Flora. http://www.probiotic.org/intestinal-flora.htm
American Museum of Natural History. http://www.amnh.org/nationalcenter/youngnaturalistawards/1998/bacteria.html
Discover Magazine – Oil Eating Bacteria Have Started to Clean the Deepwater Horizon.
Beyond Books – 2b Bacteria: The Good, the Bad, and the Ugly. http://www.beyondbooks.com/lif72/2b.asp