E.Coli

E.Coli

  • Submitted By: joe09
  • Date Submitted: 11/15/2008 3:36 PM
  • Category: Science
  • Words: 1269
  • Page: 6
  • Views: 769

Escherichia coli (more commonly known as E. coli), is a Gram-negative, non-sporulating, facultative eubacterium that is commonly found in the lower gastrointestinal tract of warm-blooded animals. E. Coli was first discovered by German pediatrician and bacteriologist Theodor Escherich in 1885. E. coli now falls within the Enterobacteriaceae family of gamma-proteobacteria. E.coli are produced in the intestine, but are not always confined to the intestine, and their ability to survive for brief periods outside the body make them an ideal indicator organism to test environmental samples for fecal contamination.
All E.Coli bacteria are not the same, they are classified by strains, they are several different strains of the bacteria. A strain of E. coli is a sub-group within the species that has unique characteristics that distinguish it from other E. coli strains. These differences are often detectable only on the molecular level; however, they may result in changes to the physiology or lifecycle of the bacterium. For example, a strain may gain pathogenic capacity, the ability to use a unique carbon source, the ability to inhabit a particular ecological niche or the ability to resist antimicrobial agents. Different strains of E. coli can be host-specific, making it possible to determine the source of fecal contamination in environmental samples. Depending on which E. coli strains are present in a water sample, for example, assumptions can be made about whether the contamination originated from a human, other mammal or bird source.

Most strains are harmless, but some, such as serotype O157:H7, can cause serious illness in humans and are occasionally responsible for costly product recalls. Avirulent strains are part of the normal flora, and can benefit their host by producing providing vitamin K2 (menaquinone) or by preventing the establishment of pathogenic bacteria within the intestine. New strains of E. coli evolve through the natural biological process of...

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