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Escherichia Coli And Its Effects On The Physiology, Morphology, Membrane, And Antimicrobic Sensitivity

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Abstract: In this experiment, each student was randomly assigned with a different species of gram- negative bacteria. The organism that I was assigned was Unknown #16. The identity of the gram-negative bacteria was determined to be Escherichia coli. The purpose of this report is to describe the various tests that helped develop a better understanding of the unknown microorganism in terms of the physiology, morphology, motility, and antimicrobic sensitivity it is characterized with. Indole production, hydrogen sulfide, and the colony morphology on the Eosin-methylene blue (EMB) plate, were the critical results that led to the conclusion that the organism was E. coli. In the indole production test, E. coli was one of two organisms,…show more content…
Theodor Eschrich, a German pediatrician and bacteriologist, is the individual responsible for discovering this specific organism. During the late 1800’s, while he was studying neonatal and infant fecal flora, Escherich used promising techniques of bacterial isolation in pure culture, fermentation reactions, and Gram staining to identify 19 bacterial species (Donnenberg, 2013) (2). Prior to the establishment of the genus Escherichia, E. coli was known as Bacterium coli commune (Percival, 2014) (3). The colonization of E. coli begins at an early stage of our life and remains with us throughout the course of our life. It is thought that the colonization begins within hours of birth since the initial strains are generally serologically identical to those present in the mother (Donnenberg, 2013). E. coli strains in humans are usually harmless and as a result can coexist with their hosts, therefore are characterized sometimes as a commensal. E. coli plays a role in maintaining healthy conditions for the human gut as well as protection against pathogenic organisms (Donnenberg, 2013). Yet, pathogenicity has been associated with certain strains of E. coli. Diarrheal diseases are the leading cause of child mortality in some regions of the world, and pathogenic E. coli strains are main contributors (Croxen, 2013) (4). Enteropathogenic E. coli (EPEC), enteohemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC),
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