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Thermus aquaticus : A bacterium that helped the world

Thermus aquaticus was first isolated from the thermal springs in Yellowstone national park.

The story of the bacterium Thermus aquatics describes a harmonious relationship between mother nature and human life in a precise way. Moreover, this bacterium changed the life we live by making a lot of advancements in science and technology, which can be related to everyday life than constricting it in the science workbench.??

However, nobody could have foreseen how famous this bacterium would be at that period.??

Briefly outlining, Polymerase chain reaction (PCR) is a molecular biology technique used extensively for different purposes. An enzyme called DNA polymerase is vital in this reaction. In the early days of PCR discovery, the DNA polymerase isolated from the bacteria E. coli was used. Unfortunately, the DNA polymerase from E. coli is not heat-stable and cannot withstand the repeated high temperature in the reaction. The enzyme had to be replaced?in?every cycle of the reaction, making it laborious and time-consuming.??

The DNA polymerase called Taq polymerase isolated from the bacteria Thermus aquatics changed the game. This heat-stable Taq polymerase made the PCR an irreplaceable technique.??

Importance?of PCR??

Taq polymerase, an enzyme from the bacteria, Thermus aquatics, changed the scientific world and techniques which in turn impacted a common man?s life positively.??

The implications of this enzyme and the PCR technique are used extensively in almost all fields, for example, pharma industries, research industries, diagnosis, healthcare, forensics, quality control, agriculture, cosmetics, etc.??

One might be?skeptical?about individual welfare this bacterium brought, by reasoning that?no individual?is not directly related to these industries.??

  • By way of example, pathogenic (disease-causing) microorganisms including bacteria, viruses, parasites, etc causing infectious diseases can be diagnosed efficiently by using the PCR than the conventional culturing techniques.?
  • In the COVID-19 pandemic, thousands of samples were tested per day in different countries by using the PCR. The results are available within hours and this faster testing and diagnosis provided an insight into the number of infected cases.?
  • PCR is also widely used in the pharma industries in drug development, especially in measuring the efficacy of drug therapy. The development of new drugs and vaccines that benefit human health often rely on PCR as part of the process.?
  • Some medicinal products such as antibiotics and insulin are mass-produced by the pharma industries by genetically modifying the existing microorganisms, where PCR plays a crucial role.?
  • HLA typing is a common PCR technique used widely in hospitals to ensure the likelihood of transplant acceptance.?
  • Food industries also use the PCR technique to detect microbial contamination in the food.??
  • In particular, Taq polymerase and PCR are an asset to the forensics. For instance, in a crime scene, the amount of sample DNA available is limited to a strand of hair, skin cells, blood, etc and it is a tedious task to isolate enough DNA from such samples. PCR provides a solution to this problem by amplifying the specific sequences from the isolated DNA and comparing it with a DNA database.
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Thermus aquatics?discovery??

Thermus?aquatics?is a?thermophilic bacteria?(thermophile is an organism that can thrive at relatively high temperatures between 41? C?to 122??C) first discovered in Yellowstone National Park in Montana, USA by the microbiologist Thomas D. Brock and Hudson Freeze of Indiana University in 1966.??

Thomas D. Brock was working on microbial ecology which focused on the study of microorganisms directly in their natural environments. He was very attentive to the research on hot springs and geysers, though his study included a variety of habitats such as marine ecosystems, freshwater lakes, soils, etc.??

thermus aquatcus was isolated from the thermal spring in Yellostone national park
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At the beginning of the fall of 1966, Thomas D. Brock with his undergraduate student Hudson Freeze started to work on the sample from the Mushroom spring, a large spring in the Lower Geyser Basin of Yellowstone National Park. This led to the discovery and culture of the bacteria called T. aquaticus.??

Later Brock isolated several cultures of T. aquaticus from the thermal area in other parts of the world. He also verified that T. aquaticus was widespread in artificial hot-water environments.??

All the cultures had an optimum temperature for growth at around 70? C?and were able to grow at temperatures up to 79? C.?

Several names crossed Brock’s mind while naming this bacterium including?Caldobacter?trichogenes, Thermus balnearius?before he finalized it as?Thermus?aquatics.??

Thomas Brock won The Golden Goose award in 2013 for his discovery of Thermus aquaticus due to the remarkable developments and all the progress made possible as a result of his discovery, following the isolation of the Taq polymerase enzyme.

?Thermus?aquatics??

Thermus aquatics is an extremely thermophilic bacterium which?can grow at temperatures above 70?C.?

However, it can?only?survive at temperatures of 50 ?C to 80 ?C.??

Thermus?aquatics?is not a pathogen and cannot grow on the human body and infect you. To know more read,?Why bacteria infect us???

DNA polymerase???

DNA polymerase is a ubiquitous enzyme found in all living cells. It synthesizes complementary DNA strands according to the template DNA in the process of replication. It also checks for the errors in the replication.??

DNA polymerase isolated from the bacteria is widely used in the in-vitro (outside the living cell) applications such as DNA amplification (PCR reactions), DNA cloning, sequencing, mutagenesis, and many more.??

DNA polymerase isolated from Thermus aquaticus which is known as Taq polymerase is the most widely used thermostable DNA polymerase. Because the Thermus aquatics were adapted to living in the water at extremely high temperatures, Taq polymerase is stable at high temperatures, even at the denaturing temperature of the DNA.??

However,?Taq?polymerase was not widely used until the Cetus corporation used it in PCR.??

PCR invention??

Almost after twenty years of the Thermus aquatics discovery, a biochemist Dr. Kary Mullius of Cetus corporation invented a technique called Polymerase chain reaction (PCR). He won the Nobel prize in biochemistry in 1983 for his discovery.??

The polymerase chain reaction is used to amplify or make multiple copies of a segment of DNA of interest. Put differently, PCR produces millions of copies of a specific DNA sequence from an initially small sample, maybe even a single copy.???

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PCR resembles the somewhat to the replication process inside the living cell. However, PCR is carried out at controlled laboratory conditions. All the necessary enzymes, buffers, and the DNA mixture are put in a small tube and kept in the PCR machine, the machine changes the temperature to suit each step in the process.??

What is PCR???

In a polymerase chain reaction, the sample (specific DNA sequence) is denatured by heat to two separate pieces of single-stranded DNA. And then a primer (a short single-stranded DNA sequence) binds to the denatured single-stranded DNA sample. The primer provides a starting point for DNA synthesis and determines the region of DNA to be copied. Thereafter, the DNA polymerase enzyme builds the complementary DNA strand by adding the specific dNTPs. After the completion of one cycle, two copies of double-stranded DNA will be produced though there was only one double-stranded DNA at the beginning of the reaction. And with each cycle, the number of copies increases exponentially.??

Taq polymerase is a crucial enzyme in the PCR.
Image credit Canva

One limitation to the PCR was that the high heat in the process can destroy the DNA polymerase isolated from the bacteria E.coli and it has to be replaced in each cycle. ?

?In 1986, Taq DNA polymerase was used in PCR which was a revolutionary breakthrough.? ?

The Taq polymerase was heat resistant as it was isolated from the thermophile Thermus aquatics. This modification made the addition of the Taq polymerase only once to the reaction mixture. ?

In 1989 Science Magazine called?Taq?polymerase?it?s?first-ever ?Molecule of the Year?.??

Great?taq?rip off??

The commercial use of enzymes isolated from T. aquaticus has been always with controversy. After?Dr.?Brock’s discovery and studies, samples of the organism were deposited in the American Type Culture Collection (ATCC), a public repository. Other scientists, including those at Cetus corporation, obtained it from the repository.???

While the commercial potential of?Taq?polymerase became evident in the 1990s, the National Park Service?labeled?its use as the “Great?Taq?Rip-off” as the park was not benefited.???

Commercial production of?Taq??

The?Taq?DNA polymerase enzyme is commercially produced by isolating the gene coding for this enzyme and expressing it in the bacteria E. coli.??

E. coli is preferable bacteria for the mass production for recombinant enzymes because of its relative simplicity, inexpensive and fast high-density cultivation, and many other factors.

Another thermostable DNA polymerase enzyme called Pfu DNA polymerase isolated from the hyperthermophile?Pyrococcus?furiosus?is also used in PCR nowadays, though?Taq?polymerase is considered as the backbone by the scientific community.??

Reconnecting with nature??

Therefore, this milestone discovery of Thermus aquatics from nature is not just a milestone in the scientific field. It granted a positive tone in our personal life even though we are not very much aware of it.??

This kind of connection, between nature and science and in turn with the humans must be communicated to the common people in a way that vibrates with their day-to-day life experience.???

Someone would certainly be troubled by the lack of a faster diagnostic technique while their beloved ones are suffering from an infection. The threat of transplant rejection after undergoing the surgery would be horrific. Assuring a food non-contaminated and safe is enjoyable to eat. Living a life without the fright of a false acquisition is relieving.??

And hence, who would not want to appreciate a scientific breakthrough? Who would not want to appreciate the microbes and resources that drive this breakthrough? Who would not want to conserve nature as it is full of resources backing our advancements in science and technology???

Thus, it is vital to communicate the scientific breakthroughs, the interrelationships between nature, science, and common people to the common people in a common man?s language. And I am pleased to use the story of Thermus aquatics from a national park to communicate the interdependence of nature and humans with you!

 

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