The Discovery of Bacteria

1. The Kingdom of Bacteria

Do not look down upon the bacterium's size, because its origin is a magnificent one. Scientists have found that early in the Archean period, bacteria had already appeared on earth. These“picky-eaters” have special interests in nitrogen within the atmosphere. They can absorb nitrogen and transform it into amino acid, which is a necessity of life, and this enables them to survive for millions of years long before the existence of human beings. Recently, some scientists were surprised to find that these bacteria had eaten half of the atmosphere. This data is both a surprise and a shock.

Although the bacterial family has a long history, this mysterious kingdom has not been known to mankind for a long time. Until three hundred years ago, a Dutchman named Antonie van Leeuwenhoek invented the microscope, which revealed the mysterious mask of these creatures. The young man was very interested in the microscopic world. Without formal education, his great interest and perseverance lead him to polish his lenses, and he eventually made a microscope capable of magnifying bacteria by two hundred times, which was the best microscope at that time (Figure 2.1).

With this powerful tool, he was surprised to find that many "small things" of different shapes were swimming in the leaching waters of hay. These are known to be bacteria. The door to an unknown world had been opened by mankind. Later, Leeuwenhoek also observed bacteria from his own mouth with a microscope, and he wrote a letter to the Royal Society and shocked Europe with his discovery.

After Leeuwenhoek, more scientists went on to explore the new world of the bacterial kingdom. Another significant person is a French chemist called Pasteur, although he was not a life-saving doctor, he was the one to confirme the relationship between bacteria and diseases. He also used a series of experiments to refute the prevailing“spontaneous generation” theory (biological creatures can occur naturally from the material elements they are in, rather than through reproduction).

Pasteur's another contribution to mankind is that he created the“pasteurization” process (heating the wine at 63.5ºC for half an hour to kill). This solved the problem of Lactobacillus wine deterioration without altering the actual taste, and this discovery went on saving the French wine industry.

Did you know that Pasteurized milk is the most consumed milk worldwide? Benefiting from pasteurization, we can now enjoy various kinds of delicious and nutritious milk. But it is worth noting that this method is not a panacea, pasteurized milk usually needs to be stored at 4ºC temperature, which can prevent bacterial growth and prevent milk from deterioration.

Among Pasteur's peers, there was a famous German scientist——Koch, his work in microbial pathogen was outstanding, and he went on winning the 1905 Nobel Prize in Physiology and Medicine. He isolated Anthrax from a cow infected with anthracnose, and transferred it into mice to infect the mice with anthrax, where he found that the pathogen isolated from mice was identical to the pathogen from the cattle. Through using scientific experimental methods, he was the first to confirm that anthrax is the pathogen of anthrax.

Later on, Koch also found the cause of tuberculosis——Mycobacterium tuberculosis, as well as Vibrio cholera which is the cause of cholera. He proposed the famous“Koch rule”, which led many scientists into overcoming causes of infectious diseases.

Under his leadership, scientists later discovered pathogens that cause large-scale infections including Corynebacterium diphtheriae, Salmonella typhi,Yersinia pestis and Shigella dysenteriae. This era became the“golden age” for the discovery of pathogens. Additionally, Koch created a series of microbiological methods, including the techniques of isolation, and culture, medium technology and dyeing technology. These discoveries brought human's understanding of bacteria onto a whole new level. In 1982, China specially issued a collection of commemorative stamps to celebrate the 100th anniversary of the discovery of Mycobacterium tuberculosis(Figure 2.2).

Another significant milestone in the long history fighting against bacteria, is disinfection proposal by a British surgeon Joseph Lister. In his clinical practice, Lister observed that many patients suffered from suppurated infections. He noticed that closed fractures (fracture without exposure the wound to air) usually do not lead to suppuration. On the other hand, even the smallest fracture (wound exposed to air) will result in suppuration. Therefore, Doctor Lister deducted that bacteria are the real cause of infection and suppuration. Furthermore, he invented a disinfection method which greatly lowered the incidence of death by infection in surgical operations.

Through the continuing efforts of many scientists, we began to gradually learn and understand these lovely“neighbors” who live among our lives, where we learned to utilize and modify bacteria to the benefits of humankind.