Conjugating Escherichia coli to Understand the Relationships between Donor and Recipient Cells through Colony Counting and Electrophoresis

Escherichia coli and its life cycle
In the year 1885, the gram positive bacterium which was initially known as Bacterium coli commune was isolated from faeces of new-born by a scientist known as Theodor Escherichia. This strain of bacteria was then later renamed as Escherichia coli after Theodore Escherich. This organism is commonly found in the lower intestine of various warm blooded organism and it has a rod shape. Humans usually get in contact with the bacteria soon after birth and thus being colonized by the organism but other major sources of contact with the organism is via contaminated foods or water.

Escherichia coli are actually able to thrive in the lower part of the gastrointestinal tract simply because of the nature which allows them to be bounded to the mucus membrane of the intestine. Within the intestine, these gram negative organisms are able to thrive and adapt to the environment simply because they are facultative organism. There are several strains of Escherichia coli, some have been found to be able to efficiently make use of glucose as their sole source of energy. This is because they have the potential of converting glucose to different macromolecules which are needed by the organism to thrive in the environment and also reproduce efficiently.

Escherichia coli has the potential of growing in region of low oxygen tension hence they could be termed as anaerobic in nature. In the absence of oxygen the organism tend to grow by fermentation and thus producing various metabolites such as acids and gas. The organisms responses to changes in their environment are due to response to environmental signals such as chemicals, pH, changes in temperature and osmolality. The listed factors or signals determine the movement of the organism simply because the organism might move towards or away from certain stimuli. It could sense the chemicals in the environment to note what needed to be produced to metabolize the chemicals (i.e. Nutrients).

Simply Escherichia coli can be described as being anaerobic in nature when found to live within the host while it could be regarded as aerobic when found in extra intestinal locations or habitat. Escherichia coli is the head of the bacteria family known as Enterobacteriaceae. There are several strains of Escherichia coli that have been found. The three major important strains being found to be virulent are the O, H, and K antigens containing strains.

Host of infections have been associated with these sets of strains and some of these infections are the urinary tract infections, neonatal meningitis and the intestinal disease (gastroenteritis). Researchers have identified and show that associated infectious agents are majorly due to the virulence determinants such as adhesins, invasins and toxins which all make them resistant to host defence mechanisms and also invade the tissue easily.

Donor and recipient the differences as its relates to the count of Escherichia coli
Bacterial conjugation is an important part of life cycle of some bacteria such as Escherichia coli. This mechanism helps such bacteria to transfer some set of genetic materials from one microbe (the donor) to other (the recipients). The transfer of genetic material usually occur in a form by which there is close approximation between the two microbes and certain form of link is formed between the cells so as to achieve both transformation and transduction of genetic materials.

Prior to conjugation, is the aggregation of genetic materials in form of transposons or plasmids within the cytoplasm of the cell of the donor. This often times is absent within the recipient cells hence often beneficial to them when they receive the plasmid from the donor via conjugation. The plasmid which is usually referred to as F-plasmid in case of Escherichia coli is also known as the F factor or sex factor. This sex factor usually stimulates the production of an outer cellular structure or organ referred to as sex pillus.

The sex pillus makes conjugation possible and its only found on the donor cells. Research as regards to the count of Escherichia coli through the use of column chromatography which help separate the Donor from the recipient cells has shown that the presence of the cell structure F Pilli are found only on Donors enhance their adherence to the cellulose that was used to separate the two cells group hence helping to differentiate between the two groups of cells i.e. the donor from the recipients. The phenotypic difference in terms of the presence and absence of sex Pilli makes it easier to actually differentiate between the donor and recipients.

Escherichia coli and antibiotics Resistance and non-resistance
Among infectious disease in paediatrics, Escherichia coli has been considered as one of the most important etiological agent responsible for diarrhoea which has been associated with high morbidity and mortality rates among children. There are several strains of Escherichia coli but the ones that are mostly implicated are the enterotoxigenic, enteropathogenic and enterohemorrhagic. Others strains such as the enteroinvasive and enteroadherents strains have also been implicated as an etiological agent responsible for the diarrhoea.

The era of antibiotics have drastically change the mortality and morbidity rates associated with bacterial infection since the discovery of penicillin but as humans tries to get rid of this microbes from our environment, the organism too are trying to adapt to those antibiotics. Such resistance to antibiotics has been found to occur within strains of Escherichia coli especially to some group of antibiotics that were initially effective against the organism.

Multiple antibiotic resistances within this group of organism have been reported to be related to the presence of the plasmids which also plays an important role in conjugation. The plasmids have been found to contain certain resistance gene. Since conjugation occur making use of sex Pilli to transfer plasmid from the donor to the recipient, antibiotic resistances were easily transmissible from one cell to the other. This mode of transmission of antibiotic resistance makes resistance to certain drugs once achieved by a cell especially the donor with the plasmid to be transferred at a rapid rate to other cells (recipients).

Resistance has also been found to be transmissible from more virulent pathogenic species to those strains that were not initially pathogenic. Resistance to certain drugs such as ampicillin and tetracycline has been found to be common among Escherichia coli. Antibiotic resistance by Escherichia coli simply demonstrates evolution that could occur among bacteria and it demonstrate how effectively genetic information can be transferred from one cell to another so as to achieve effective adaptation to its environment.

Non-resistance can be said to occur when Escherichia coli fails to develop a resistance to certain drugs over a period of time. This makes the bacteria sensitive to those drugs and it could be attributed to inherent deficiency in the mechanism that is responsible for development of resistance. Hence in this situation, when there is infection of the organism, drugs that were found to be active against the organism could be used effectively to destroy the colonies of the bacteria.

Importance of counting bacteria in colonies
There are reasons why we actually need to count the colonies formed by Escherichia coli. One important reasons as regards to this can be referred to the roles of colony in understanding the nature of the organism i.e. colonies will help the microbiologist monitor the growth rate of the bacteria and also if there are any changes that affect the colonies as regards to any experiment being conducted by the microbiologist. Another importance of counting colonies can be attributed to the importance of precision and accuracy to measurements in microbiology.

Indication for electrophoresis DNA separation, plasmid and denaturing
There are several indications for the electrophoresis of Escherichia coli. Identification of proteins being produced by the organism, differentiation between the donor of the organism and the recipient, for epidemiological purposes in identification and separation of different strains of the organism, to monitor outbreaks and differentiate between the outbreak and sporadic strains, to understand the nature of transformation of the organism by acquisition of recombinant plasmid and to separate resistant colonies from non-resistant colonies of Escherichia coli. Electrophoresis of Escherichia coli could also be important in the areas of determination of the motilities of different strains of the organism.

Conclusion
In conclusion, Escherichia coli are bacteria of great economic importance. It contribute greatly morbidity and mortality rate among infants and despite the fact that there are different forms of antibiotics that have been produce to treat the infection caused by the organism, there are increase in rate of antibiotic resistance to host of those antibiotics. The increase in rate of antibiotic resistance we see recently has been understood to be a result of effective means of genetic transfer between the donor and recipient cells. Conjugation between Escherichia coli stands to be the main link between transmissions of genetic material from one generation to another. Techniques of counting the colonies and electrophoresis to understand various aspect of the organism such as differentiating between strains and identification of their plasmids all serves as a backbone to understanding the nature of the organism and could be a future means of achieving control of the bacteria.

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