The Microbiology of the Vibrio cholerae Bacterium
Cholera is a deadly disease that has caused a worldwide phenomenon throughout history. Its imperative weapon, the Vibrio cholerae bacterium, has allowed cholera to seize control and wipe out a huge percentage of the human population. V. cholerae’s toxins are the primary causes of cholera’s lethal symptoms. The bacterium contains toxins that help it accomplish its job of invading the human system and defeating the body’s powerful immune system. With its sibling bacterium Escherichia coli, V. cholerae has become one of the most dominant pathogens in the known world. V. cholerae’s strategies in causing the infamous deadly diarrhea have been widely studied, from the irritation of the intestinal epithelium to the stimulation of capillary leakage, as well as the internal effects of the disease such as the Peyer’s patches on the intestinal walls. Overall, the Vibrio cholera bacterium has made cholera a tough disease to overcome, and because of its deadly virulence factors, cholera has become one of the most frightening diseases a human body could ever encounter.
Cholera is a diarrheal illness in the intestinal tract caused by the gram negative bacterium Vibrio cholerae. Vibrio cholerae is a member of the family vibrionaceae and of the genus Vibrio, which are fresh, brackish, or saltwater dwelling anaerobes that have the ability to ferment. Vibrios are highly halophilic, which means that they need salt-rich environment in order to thrive. They are usually rod-shaped and are either straight or curved, and are very sensitive to acid. Vibrios are motile organisms that travel with a single flagellum, and depend on saccharose sugar and starch for their growth and development. They use fermentative or respiratory metabolism and are heterotrophic, which means that they are not able to create their own food. Instead, vibrios obtain food through mutualistic, parasitic, and pathogenic relationships with their chosen host.
(Finkelstein. Par 13-15.)
The Cholera Toxins and Cell Receptor Binding
Vibrio cholerae generates several toxins that are perilous to eukaryotic cells. The toxin that causes the diarrheal disease cholera is the cholera enterotoxin called choleragen (CT). It has A and B subunit toxins: toxin A is responsible for enzymatic and intracellular functions, while toxin B is responsible for binding the toxin to the eukaryotic cell receptor. The cholera enterotoxin (CT) has been shown to have biological similarities with the Escherichia coli enterotoxin (LT), and is similar to the E.coli enterotoxin in both structure and function. Both enterotoxins have helical structures and three-stranded, antiparallel pleated sheets, as well as a disulfide bond that connects the N and C terminal halves of the monomer. The tryptophan in subunit toxin B is vital in receptor binding. Tryptophan is stimulated by a cysteine component, and is delivered to the eukaryotic cell membrane by...