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  • Writer's pictureElizabeth Deyett

Who was Robert Koch: A Great Scientist Or A Determined Doctor?

Updated: Nov 11, 2022

Professor Xi at the front of a classroom to give his lecture on "Who was Robert Koch: A Great Scientist Of A Determined Doctor

Good morning everyone.
Class: "Good morning Professor Xi!"

Recently, we have learned all about Louis Pasteur so I thought we would continue diving into this era of microbiology and talk about another great scientist, and famed rival of Louis Pasteur, Robert Koch. He focused on microbes that made both animals and the giants ill, making him a superstar in their world of medical microbiology. Although he was not particularly kind to us, a mad torturer of microbes really, I have to acknowledge the scientific method he used, a method which they still use today. Alright everyone, let us learn about this important figure in microbiology.

Robert Koch’s Beginnings

Robert Koch was born December 11, 1843, and was the 3rd son of Herman and Mathilde Koch in Germany. Growing up, he did very well in school, excelling in science, math, and could speak several languages. He also showed a particular interest in nature as he would collect insects and plants. He had a particular interest in examining moss under a magnifying lens, although there's no evidence he found any long ancestral descendants of Coach Timmy’s. It was at this time that he met his future wife, Emmy Fratz, they grew up together, playing as children, and romancing each other as adolescents. She cared for him so much that at one point she saved up her money to buy him a new microscope and collect samples for him to look at.

Class: "Ewww!"

Larry: "Nothing is more disgusting than the Giant’s obsession with romance. Blaargh!"
Well Larry, not every microbe can produce through binary fission, some need to create the next generation with genetic material from two parents. But back to the lesson.

Despite his intellect, it almost seemed like Koch would not be able to attend college. His father was an advisor to the Prussian government in regards to mining, but his family was poor as his parents were feeding 13 mouths in addition to their own. However, things turned around when his parents inherited some property, giving him the finances he needed to go to the University of Göttingen in 1862. It was there that he studied medicine. He studied under the notable Physician Jacob Henle, who influenced Koch’s future. In particular, Jacob wrote 2 things that may sound similar to those familiar to the Giant’s field of microbiology:

2 quotes from Jacob Hanle that would ultimately lead to Koch's Postulates.

Keep these quotes in mind as you learn about Koch’s contributions to science, you will see how these influenced his future research.

Koch graduated in 1866 and decided to take a postdoctoral position at the University of Berlin. He was able to finish in one year (highly unusual!) and was offered an assistantship at the general hospital in Hamburg. It was during this time he was “cutting one's teeth,” as he ended up moving around and working different positions around the country including a resident physician in Langenhagen, moving to the town of Niemegk, and landing in the town of Rackwitz. It was during this period that he married Emmy and their daughter was born.

As you may remember when discussing Louis Pasteur, the Franco-Prussian war was going on around this time. Koch was more than enthusiastic when it came to volunteering and he joined the military in 1870 where he acted as a physician, first starting in a field hospital and then transferring to a military hospital acting as the chief medical officer, treating soldiers for typhoid fever. His stint was very short as he was discharged after 6 months to go back to his town to continue his practice.

In 1872, he moved again, becoming the district physician of Wollstein. During this time, Pasteur was performing experiments to prove communicable diseases and Joseph Lister was showing that wounds can heal without infection if the dressing, tools, and hands were sterilized before an operation. It should be noted that Koch's interest in the natural world did not end. In his new position, Koch decided to split his medical office in half, with one side to treat patients and the other to continue his experimentations with his own makeshift equipment. It was this little lab that would change the course of his life.

Student: For good or for bad?"
Depends on who you ask, for Koch it would be his first scientific breakthrough, for microbes, well it would become a microbial torture chamber.

Koch’s First Big Discovery: Anthrax

The year was now 1876; Koch had been at his post for 4 years now and he was the beloved doctor in the area, so much so that patients came from near and far to see him. It was at this time that Anthrax was taking in the scenes and spreading across Europe for the past couple of years and had finally come to Koch’s neck of the woods. Koch had been seeing it for several months and it was killing the livestock without warning; the animals would refuse to eat followed by head and body drooping and would soon be dead. Other livestock would come down with the sickness, even farmers/hands were getting sick; they would develop boils, fits of coughing and eventually die.

Koch was running around, collecting blood samples from everything: the affected, the dead, butcher shops, etc. He would then look at it under the microscope where he saw little sticks floating in the blood of the diseased, some were rods and others were threadlike, but in healthy individuals he could not find these structures. Other scientists of the day had seen these structures as well, but could not directly tie it to the disease, or offer any proof of causality. So, the question Robert was asking was: are these rods alive and if so how do I prove it? He needed to see the microbe multiply to get these answers.

First, Koch wanted to see if he could transfer the disease. He inoculated mice with a wooden sliver that had previously been dipped in diseased material. By the next morning, the mouse was dead and he found the rods in the blood. He then took the blood of that mouse and inoculated it into another mouse using the same method as before, repeating the process 30 times, all with the same result. But how could he see these microbes grow? He was having trouble isolating the microbe, as whenever he would try there was contamination. Koch eventually found a solution: he gouged out a well in a thick glass slide, sterilized a thin slide and added a drop of ox eye liquid. He then slid a bit of spleen from a dead mouse into the liquid and sealed the drop with the well of the thicker slide, isolating the specimen from the outside. With this method, he was able to see the rods divide and grow without any contamination. He then took a little bit of this growth and repeated the process over and over with the same result. After 8 times he was sure the culture was pure, so Koch inoculated another mouse with the pure material which died and he could see the rods in the mouse's blood.

However, Koch found that sometimes the bacteria would perish as fast as they would kill. This is due to the exposure to sun rays, more specifically UV rays, which damage microbes' DNA.

Class: "Booooooooo!"

Yes I know class, but not all microbes are sensitive to sunlight, they have many ways of protecting themselves.

Koch asked, how was it that this microbe survived in the environment, how was it that in some fields animals were fine and in others, they would perish? One day Koch stumbled upon oval bodies present on one of his slides. At first, he thought it was contaminated and didn’t give the slide a second thought. However, several weeks later he saw the same ovals when looking at the slide again. Koch decided to add the ox eye liquid and the ovals sprouted and started to grow again.

Anna: "Professor Xi like stop making this sound so mysterious! We all know you're talking about spores."

Yes I am, no need to be rude Anna not everyone knows about or produces spores.

This explained how they survived the environment; they are in a protective state a microbe enters and will stay there until a favorable environment comes around.

Back to our story, he then injected these microbes into mice and saw the same result, death. Koch had identified the causative agent of Anthrax, seen the entire life cycle of the microbe, and showed that a disease was caused by a microbe, all by the age of 33.

With these results, he wrote to the esteemed Dr. Ferdinand Cohn of the Botanical Institute in Breslau who was known as the greatest Bacteriologist in Germany at this time. Koch was then invited to the Institute and, in April of 1876, he presented his results demonstrating in front of Cohn, Julius Conheim, a pathologist who, among many other discoveries, pioneered the theory of inflammation, and other scientists of the budding field. In the end, Koch was congratulated and he published his findings.

Moving On Up

In 1880, Koch was appointed the Imperial Health Officer in Berlin where he was provided everything needed to conduct research and got 2 assistants: Friedrich Laeffler and George Gaffkey, whom he would work with for the majority of his research career and remained friends until his death. It was during this time that Koch tackled another problem: there was no simple way of isolating microbes or getting pure samples because microbes were being grown in liquid making it nearly impossible to isolate.

Hugo: "Well… isn’t it because we don't want to be alone?"

Good point Hugo, microbes are almost never by themselves, they need to interact with others to survive, but in science, it is hard to tell what a microbe is doing or causing something unless it is by itself, though this was true in the beginning of microbiology, but not as much nowadays.

One day, Koch saw a slice of boiled potato that had been left on the counter overnight and there were different colored specs that ended up being different microbes when observed under the microscope. More importantly, the colonies were homogenous or pure and were isolated from one another.

Gelatin had been attempted to no avail, but Koch was able to change the gelatin properties to get it solid enough to isolate colonies. It was not Koch, in the end, that was able to come up with the solution to this problem. Gelatin cannot remain solid at certain temperatures. In fact, at 25C (77F) it turns back to a liquid.

Psydney: "But like a lot of us like to relax and chill at temperatures below that."

Correct, many of you can, but those that have adapted to growing in and on the giants and other warm blooded animals need a higher temperature to grow. That's why you always see those microbes with coats and sweatshirts on.

Larry: "That may be true, but we make them look good!"

Yes, you all look fabulous! Back to the lesson!

In 1882, Fannie Hesse, a wife of one of the researchers in the lab, suggested replacing the gelatin with agar which is derived from seaweed. It is superior to gelatin, as it is clearer and, once hardened, can be placed in up to 60C (140F) without melting and is resistant to bacterial enzymes. Agar revolutionized microbiology and is still used today.


Now we will get into the discovery that made Koch a superstar, Mycobacterium tuberculosis.

Larry: "Hey Myckee that's you. "

Myckee: "No….that's…my…betrayer….of….a….cousin….and….he's….on….the….top….ten….most….wanted….list."

In the giants, this microbe can cause an infection that is slow and may take months to years to develop and even longer to die! At one point, the Giants even believed people infected with this microbe would turn into vampires! Because of this, many thought it was an inherited disease as it seemed to run through families. Despite this, there had been some scientific discoveries; the first was the discovery of tubercle in the deceased (tubercles are lesions that contain the bacterium, immune cells, and dead tissue). Also, Cohnheim had proven that it could be transmitted from the giants to animals.

Koch began studying the microbe in 1881 and would continue doing so for the rest of his life. When he studied this disease he used what is now known as Koch’s postulates. To prove a microbe is a cause of a disease:

Professor Xi explain the 5 steps of Koch's Postulates to Find, isolate, test, observe and reisolate a microbe to determine it as the causative agent of an infectious disease

He started first by replicating Cohnheim’s experiments, but could not see an organism, a problem which was made more difficult by the fact that it is a smaller and slower growing organism compared to other microbes. After failing with many dyes, he used methylene blue, and voila, he was able to see small bacilli. Next, he needed to grow it and after 2 weeks of waiting, Koch finally saw growth. Koch then inoculated the microbe into animals that eventually died and he was able to re-isolate the bacteria from its tissue, just like the Anthrax studies.

He presented his results in 1882 at the Berlin Physiological Society in front of Emil Heinrich du Bois-Reymond, a German physician, physiologist, and the co-discoverer of the nerve action potential, Hermann von Helmholtz who contributed to the eye and auditory research, Paul Ehrlich who discovered the first cure for syphilis and developed the precursor to gram staining, Emil von Behring who would discover an antitoxin to diphtheria, Cohn, Chohnheim, his assistants; in other words some of the biggest Scientific minds in Germany at the time. Koch published his findings a week later, calling the microbe tubercle bacillus and it was this publication that made him famous worldwide. He even had a follow-up paper in 1884 showing that the microbe could be transmitted by breathing it in.

Well, that is it for today everyone.
Class: "Awwwwwww!"
Professor Xi concluding his lecture of Robert Koch.

Class: "Bye professor Xi!"

The majority of the information in this blog was provided by the book Robert Koch Father of Microbiology by David C. Knight published in 1961.

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