Identification of microorganisms

Subject: Science
Type: Analytical Essay
Pages: 4
Word count: 1000
Topics: Microbiology, Bioethics, Biology, Scientific Method, Stem Cell


There is a ubiquitous distribution of microorganisms in the environment despite the fact that sometimes we think we are free from them. Since they are microscopic, poor cleaning methods allow them to multiply still unnoticed. They are likely to be found in large numbers in areas where food is prepared since they also depend on some of the nutrients present in the foods we cook (Kimiran-Erdem et al., 2007). The effectiveness of the cleaning methods compromise the death of some of the microorganisms hence they are consumed together with the food. As a result, they are directed to the mucosal membranes of the GIT which is a favorable breeding site for most bacteria. Once they start causing disease, it becomes unknown the cause of the illness since it had prior been assumed that clean conditions had been maintained. Alternatively, if foods are well cleaned, a dirty environment still allows the proliferation of the microorganisms. The microbial load in our environment could be used to explain the frequently reported pandemics globally whose cause was unknown (Su et al., 2012). Basing on the previous laboratory works, this paper gives a stepwise identification of the particular microorganism that could be the cause of the intercontinental pandemic.

The Systematic Identification of Bacteria

Since it had been established that the causative agent of the pandemic could be a bacterium, the identification methods were mainly based on identifying bacteria. This procedure was deemed essential because it narrowed down to a specific bacterium; hence it makes the treatment program easier. With the increasing resistance offered by bacteria on antibiotics, it is necessary to administer drugs that are targeting a specific bacterium. The process, therefore, began with the identification of the bacteria through various tests that reveal their characteristic features. The laboratory tests began with the growth of bacteria on various suitable media which provide essential nutrients for their growth and proliferation. The bacteria were contained in the sample provided, and favorable conditions were provided by incubating under favorable temperatures. Once colonies had grown on the agar plates, pure colonies were picked for further identification which employed the biochemical tests. However, some bacteria can still be identified from the nature of colonies formed e.g. Staphylococcus aureus and Staphylococcus epidermidis which forms a golden and white pigment on MacConkey agar respectively (Nagar et al., 2013). The biochemical tests which were subsequently done to separately identify the bacteria included catalase, oxidase, urease tests, and Gram staining (Su et al., 2012). It was then possible to identify specific bacteria that were the cause of the pandemic reported.

Gram Staining

It is a supplementary technique to microscopy since it supports the ability to visualize the difference between Gram positive and Gram negative rods and cocci. The differences in the arrangement of the cocci can also be visualized hence it narrows down the identification process. The Gram staining process involves the use of crystal violet which is the primary stain and sufranin which is the secondary stain. The process also involves the use of iodine and ethanol which fixes the primary stain onto the cell wall and decolorizes respectively. The ability of the cells to either retain the primary or secondary stains characterize them as either Gram negative or Gram positive, a feature that is easily observable under the light microscope.

Catalase Test

It is a biochemical test that seeks to identify whether the isolated microorganisms contain catalase enzyme. This aspect is tested by the biochemical role of catalase which is to catalyze the breakdown of hydrogen peroxide into hydrogen and water. In the practical, the test was done by placing a colony on a slide containing a few drops of hydrogen peroxide, a similar protocol that would be observed in the current study. Positive tests were characterized by effervescence which evidence production of hydrogen gas. Staphylococci are catalase positive while Streptococci are catalase negative.

2 H2O2 → 2 H2O + O2

Oxidase Test

This test was aimed at identifying colonies with microorganisms containing cytochrome c oxidase which is involved in the bacterial ETC (Yan & Sadowsky, 2007).  If the oxidase test is positive, then the bacteria are most likely to be aerobic since the ETC involves the use of oxygen as a terminal acceptor molecule. However, a negative test means that the microorganisms could either be anaerobic, aerobic, or facultative since they could be utilizing other oxidase types for the ETC. Examples of oxidase positive bacteria include Helicobacter pylori, Vibrio cholera, and Campylobacter jejuni. Typically, Enterobacteriaceae are oxidase negative (Su et al., 2012).

Other Tests

Other tests that could be performed include the indole and urease tests. Indole test identifies bacterial species that are capable of converting tryptophan into indole, a change that is characterized by the formation of a red ring on the meniscus of the peptone water containing the colony after incubation (Kimiran-Erdem et al., 2007). Positive results mainly differentiate Enterobacteriaceae from the other genera. Urease test would also be done to test the production of urease enzyme which catalyzes the breakdown of urea into ammonia and CO2. The conversion is affirmed by the presence of phenol red indicator which changes from yellow to red once the pH has been raised when ammonia is produced. It a tests that characteristic of identifying Helicobacter pylori which contain urease (Nagar et al., 2013).


Pandemics may erupt as a result of infestation with microorganisms without the knowledge of those who are affected. This paper has discussed various tests that could be done with the samples provided so as to come up with specific bacteria that could be dangerous to people’s health. The tests begin with the general culturing of the bacteria in the samples so as to allow all of them to grow after which pure colonies are further examined. This process is essential because it leads to the prescription of the right antibiotics against the present bacteria hence improves prognosis. Also, the problem of antibiotic resistance is reduced through the administration of appropriate drugs without trial and error.

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  1. Su, C., Lei, L., Duan, Y., Zhang, K. and Yang, J., 2012. Culture-independent methods for studying environmental microorganisms: Methods, application, and perspective. Applied Microbiology and Biotechnology, 93(3), pp. 993-1003.
  2. Yan, T. and Sadowsky, M. J., 2007. Determining sources of fecal bacteria in waterways. Environmental Monitoring and Assessment, 129(1-3), pp. 97-106.
  3. Kimiran-Erdem, A., Arslan, E.O., Sanli Yurudu, N.O., Zeybek, Z., Dogruoz, N. And Cotuk, A., 2007. Isolation and Identification of Enterococci from Seawater Samples: Assessment of Their Resistance to Antibiotics and Heavy Metals. Environmental monitoring and assessment, 125(1-3), pp. 219-28.
  4. Nagar, V., Shashidhar, R. and Bandekar, J.R., 2013. Characterization of Aeromonas Strains Isolated From Indian Foods Using Rpod Gene Sequencing and Whole Cell Protein Analysis. World Journal of Microbiology and Biotechnology, 29(4), pp. 745-52.
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