The Role of Bacteria in the World

By Federica Ferrari

A War We Need

Coccolithophores, tiny phytoplankton that live in the ocean, fight a gruesome, difficult war against marine viruses on a daily basis.

The coccolithophores fight off viruses by when the virus begins to get near it, they swallow it and in many cases are able to shut down their body, virtually committing suicide in order to kill the virus along with themselves. However, in some cases, this isn't possible, because the virus prevents them from doing so. Either way, the coccolithophores end up dead, but as they die, they send out signals for others to see as a warning that a virus is near. These tiny organisms have more sense of sacrifice than most humans do, which is incredible.

The war against the viruses is extremely important because the tiny coccolithophores are responsible for half of the works oxygen. Many believe that the amazon rainforest is the lung of the earth, and while that's partly true, so are tiny phytoplankton in the ocean.

Bacterium #1: Aeromonas hydrophila (A. hydrophilia)

Aeromonas hydrophila is a bacterium that can be found in fresh, brackish, chlorinated and unchlorinated water supplies worldwide, especially in warm climates, where strains tend to be more numerous. These have been found even in bottled and chlorinated water, making it extremely common.

Some strains of Aeromonas hydrophila are known to causing disease in fish and amphibians as well as in humans, who get infected through open wounds or by swallowing contaminated water or food. It is especially tricky to kill because it is a resistant bacterium. Aeromonas hydrophila is resistant even to chlorine and cold temperatures. Aeromonas hydrophila causes a variety of different diseases in fish as well as humans. The presence of this ubiquitous, or very common, bacterium in aquatic environments provides many opportunities for fish and amphibians to come into contact and ingest these dangerous organisms. It is very toxic to a number of organisms. When it enters the bodies of fish, amphibians or humans, it travels via the bloodstream to the first available organ and attacks. It is especially fatal in fish and amphibians because of their relation with the water. Aeromonas hydrophila is related to a disease found in frogs called red leg, which causes fatal hemorrhage.

Fish, on the other hand, when infected with Aeromonas hydrophila, develop ulcers, fin rot, tail rot, and hemorrhagic septicaemia, which causes lesions that lead to a variety of problems, such as scale shedding and hemorrhages in the gills and anal area. This bacterium is also pathogenic to humans, because it causes gastroenteritis, which can affect everyone.

In conclusion, the effect of the Aeromonas hydrophila on its environment (aquatic) is that it is very dangerous and harmful, however, it is also vital. The Aeromonas hydrophila, while killing or sickening many "innocent" life forms, also kills much more dangerous viruses that lurk around the waters. It is both a blessing and a curse on the aquatic environment,

Bacterium #2: Bacillus megaterium (B. megaterium)

Bacillus megaterium is a gram positive, endospore forming, rod shaped bacteria. It is considered aerobic. It is found in soil and considered a saprophyte.

It is a very large bacterium, almost 100 times larger than E.coli.

These are an example of a bacterium that has been used on some crops to suppress the disease-causing fungus Rhizoctonia solani. B. megaterium has been recognized as an endophyte and is a potential agent for the biocontrol of plant diseases. Nitrogen fixation has been demonstrated in some strains of B. megaterium, a positive phenomenon.

B. megaterium can survive in extreme environmental conditions such as desert environments due to the spores it forms. Where there are favorable conditions the spores can grow and divide to form vegetative cells. B. megaterium is used as a soil inoculant in agriculture and horticulture. It's effect on the environment is positive, helping suppress disease causing funguses and being able to perform nitrogen fixation.


The war we need:

Radiolab. (n.d.). Radiolab Podcast Articles. Retrieved April 3, 2014, from

Aeromonas hydrophila:

Aeromonas Hydrophila. (n.d.). - MicrobeWiki. Retrieved April 3, 2014, from

Bacillus megaterium:

Bacillus megaterium. (2014, March 30). Wikipedia. Retrieved April 3, 2014, from

Bacteria. (n.d.). DPI.NSW.GOV. Retrieved April 3, 2014, from

Science Stock Photography. (n.d.). Bacillus megaterium. Retrieved April 3, 2014, from