Bacteria has the connotation of disease and rot, of rampant negative growth. People worry about infections, and attempt to halt the spread of bacteria. E. coli and staph are frightening words to hear from a doctor. Antibacterial hand cleaner is available in most public places, and every bottle on the household product aisle boasts of its bacteria killing properties.
Unfortunately, no one praises bacteria for all the ways it helps humanity.
The ecosystems of the planet would not be in their current state without bacteria. Decomposition releases valuable carbon dioxide back into the environment. Nitrogen fixing locks nitrogen into a useable form for plants, and fermentation creates many types of food and drink. Digestion and photosynthesis wouldn't be possible without symbiotic relationships.
Decomposition benefits humans indirectly, although invaluably. Bacteria break down the cells of dead organisms, releasing trapped carbon and nutrients back into the environment, and disposing of the excess flesh. If carbon remained trapped in dead bodies, plants would lose their source of fuel, and would no longer be able to provide oxygen to the beings that use it. Organotrophs represent the pinnacle of recycling.
Plants cannot use gaseous nitrogen, but they require it for their life cycle. Certain bacteria convert the gas-form of nitrogen into a solid state which plants absorb through their roots.
In a similar way, fermentation converts one substance into another. Most well-known is the process of yeast changing sugar to ethanol for alcoholic beverages, but there are plenty of products humans have created that are dependent on bacteria. Cheese, sour cream, buttermilk, creme fresh, sauerkraut, vinegar, chocolate, pickles, sausage, and many other foods only exist because bacteria was introduced at some part of the process.
Because ancient eukaryote bonded with plant cells, photosynthesis changed kingdoms of life. Plants provide a safe place for bacteria, and the bacteria provide energy for the plants.
In a similar relationship with people, bacteria teem in human colons, aiding in the digestion of nutrients otherwise indigestible. Human gut flora synthesize vitamins, convert sugars to lactic acid, boost immunity, and tear down carbohydrates. Properly balanced bacteria can prevent pathogens from taking over, and the make up human flora can even help identify what region a person is from.
Gut flora boost immunity from inside, and many other bacteria have been harnessed to work for human health. Probiotics are the opposite of antibiotics, and work to boost existing microorganisms and prevent pathogens. While not all claims have been fully substantiated, preliminary use of probiotics has shown results with combating antibiotic associated diarrhea, colon cancer, lactose intolerance, irritable bowel syndrome, and many other health issues.
Bioremediation and pesiticides are just some of the industrial uses of bacteria. Oil spills can be cleaned up with the help of hydrocarbon-eating bacteria, and other strains can even be used as an alternative to pesticides. With a fast growth cycle, microbiologists can quickly work bacteria into other uses.
While there are many harmful bacteria, there are just as many helpful strains. Bacteria deserves human respect and praise as much as they do fear and to be wiped out.