The Science of Microbiology
Microbiology is generally understood as the sub-field of biology, which studies microscopic organisms, such as bacterium and virus. Discoveries have played a major role in the development of this field. In fact, discoveries of microorganisms proved to be watershed, which gave direction to the field of microbiology. Various scientists contributed to its development; however, the contribution of some scientists was more significant than others.
PART-1
Describe Koch’s Postulates and briefly summarize his contributions to the field of Microbiology.
Robert Koch is considered the father of modern microbiology. His contribution in the field of infectious diseases led him to win a Nobel Prize in 1905. He developed different techniques and methodologies to understand the host-pathogen relationship better. His research helped him to develop four basic postulates/principles to understand and specify a microorganism to a particular disease; these postulates are also known as Koch’s postulates. Robert Koch was the first person to identify that anthrax was caused by a bacterium Bacillus anthracis by using cultures. Also, the concept that tuberculosis was inherited and not caused by external factors was proved wrong with him by identifying its causative agent, which was Mycobacterium tuberculosis, in the year 1882. He also observed the phenomenon of acquired immunity by examining Plasmodium parasites, which causes malaria, in the blood samples of the Papuan people.
During his life, Cholera was a serious medical challenge, as it occurred very frequently in different parts of the world. In some countries, it was occurring more regularly than the others, which compelled the scientific community to isolate causative factors or agents of Cholera. During that period, several scientists were working on identifying and isolating the causative factor/agent, one of which was Robert Koch. It is apparent from the study of various attempts, of that time, to identify causative agents, that Koch’s work was more detailed and conclusive (Brock, 1988).
The indirect contribution of Robert Koch to the field of Microbiology is immense. He mentored several students, who later discovered various causative agents.
Postulates
- In an organism, suffering from the disease, microorganisms (of a particular type) must be found in abundance, which should not be present (in same size/ratio/percentage) in a healthy organism.
- Through a repeatable process, microorganisms should be isolated from a selected organism (that has the disease) and must be grown in pure culture (for study/experiments).
- Cultured microorganisms must cause disease, if they were introduced into the healthy organism, through a medical procedure/process.
- The microorganisms, which were introduced into the healthy organism, must be able to re-isolate and these microorganisms must be identical to the original causative agent.
PART-2
Describe the symbiotic role of your chosen microbe within our Microbiome.
Pseudomonas aeruginosa
The chosen microbe, for this academic exercise, is Pseudomonas aeruginosa. As per information, it is a type of bacterium, which is gram-negative and it is rod-shaped. This bacterium causes a range of diseases in both plants and animals. It is of great medical importance because of its various aspects which distinguish this bacterium from other bacteria. One of the features of this bacterium is that it develops into pathogen, in a favorable environment, and in that state, it is resistant to various drugs (multi-drug resistant). Another feature, of Pseudomonas aeruginosa, is that it has an innately advanced system about antibiotic resistance (Sadikot, Blackwell, Christman, & Prince, 2005).
Microbiome
Naturally, it thrives in soil, water, plants, on the skin (of animals) and in creating environments. Pseudomonas aeruginosa can thrive in both normal and extraordinary conditions. For instance, Pseudomonas aeruginosa can exist in extremely low-oxygen atmospheres, which allows this bacterium to colonize diverse environments. Another aspect of the selected bacterium is that it consumes various kinds of organic materials for food, which facilities its survival and colonization in physically different environments (Teitzel, Geddie, Kirisits, Whiteley, & Parsek, 2006).
Symbiotic Role of Pseudomonas aeruginosa
From the study of the selected microbe, it is apparent that the symbiotic role of Pseudomonas aeruginosa is parasitic. However, its relation with the host, in the early stages, demonstrates Commensalism, rather than parasitism. It is because Pseudomonas aeruginosa is an opportunist pathogen, which waits for the host’s immunity to alter (diseased condition). When this development occurs, Pseudomonas aeruginosa bacterially affects (adversely) the body of the host. Therefore, we can say that during different stages, the symbiotic role of selected microbe, Pseudomonas aeruginosa, is different. Mostly, it develops into a pathogen when it gets the opportunity.
Development into a Pathogen
In the inert state, when it has a commensalism relationship with the host, it is an ordinary microbe, which does not cause any disease. However, when this opportunist microbe develops into a pathogen, because of the impairing of the immune system, it causes various diseases. Therefore, it is evident that this microbe develops into pathogen (disease-causing bacterium) under particular conditions. Generally, it transforms into a pathogen, when other diseases have weakened the immune system of the host, which provides it an opportunity to colonize (Hurst, 2016).
As a pathogen, they produce particular types of toxins, which affects (inactivate) proteins in humans. For instance, Pseudomonas aeruginosa, uses its colonization capacity as an instrument (exotoxin) to inactivate special proteins in humans called eukaryotic elongation factor. It makes it apparent that this microbe transforms itself into a pathogen, whenever the conditions allow this microbe to develop. It also suggests that the transformation of the selected microbe primarily depends upon conditions, which include environmental and host conditions.
References
Brock, T. D. (1988). Robert Koch: A Life in Medicine and Bacteriology. ASM Press.
Hurst, C. J. (2016). The Rasputin Effect: When Commensals and Symbionts Become Parasitic. Springer.
Sadikot, R. T., Blackwell, T. S., Christman, J. W., & Prince, A. S. (2005). Pathogen–host interactions in Pseudomonas aeruginosa pneumonia. American journal of respiratory and critical care medicine, 171(11), 1209-1223.
Teitzel, G. M., Geddie, A., Kirisits, M. J., Whiteley, M., & Parsek, M. R. (2006). Survival and growth in the presence of elevated copper: transcriptional profiling of copper-stressed Pseudomonas aeruginosa. Journal of bacteriology, 188(20), 7242-7256.
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