According to our class text book, spontaneous generation

According to our class text book, spontaneous generation was that people believed that living things and such were created from non-living material such as worms on rotten meat. There were several scientists that did several different experiments to try and disprove this spontaneous generation theory. One of those experiments I’m going to talk about is the experiment by Louis Pasteur.

In Louis Pasteur’s experiment, before he did anything he boiled the broth, in a swan neck flask, to sterilize it. Air was able to escape through the end of the flask while boiling. While the broth was cooling air from the environment was able to enter at the end of the flask.

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After a while, microorganisms from the air had settled in the dip of the swan neck flask. This helped disprove spontaneous generation because the broth was still exposed to air, but the microorganisms couldn’t travel against gravity to get into the sterile broth. A couple years later, the broth still remained sterile and the microorganisms remained in the dip of the swan neck flask. Louis Pasteur then tilted the flask so that the microorganisms from the air came in contact with the sterile broth inside the flask. In just about a few hours to days later the microorganisms begin to multipy in the broth.

Despite Louis Pasteur’s experiment, many people were still skeptical of Louis Pasteur’s experiment disproving spontaneous generation because no one else could duplicate his experiment that he did. This experiment also discontinued the arguments that the unheated air or broths contained a vital force for spontaneous generation. This also led the belief that living things were produced from other living things, called the theory of biogenesis. Almost a hundred years before Louis Pasteur did his experiment, a scientist, John Needham, showed that different flasks containing different broths had microorganisms arise even when the flasks with broth were boiled and sealed with a cork. With that being said, it could make people still skeptical of Louis Pasteur’s experiment still, even though most scientists were convinced with Pasteur’s experiment.

Another experiment that backs up Louis Pasteur’s experiment is the experiment by John Tyndall. John Tyndall proved that several different types of broth required different lengths of boiling time to be considered sterilized. Some broths were considered sterilized after 5 minutes and others weren’t even sterilized after several hours of boiling. Broth made from hay was boiled for five hours and still contained living microorganisms in it. John Tyndall concluded microorganisms can exist in two forms. One being a cell killed by boiling and the another that is heat resistant. The same year, Ferdinand Cohn discovered endospores. Endospores is the heat resistant forms of some bacteria.

This would explain the difference between Louis Pasteur’s experiment and the other experiments. Soil is typically where endospores were commonly found which would explain why the broth made from hay wasn’t considered sterilized until after several hours of boiling. In Louis Pasteur’s experiment, he only used broths that were made with sugar or yeast extract.

Since he only used broths made with sugar and yeast extract there is a good chance that when Louis Pasteur did his experiment there was not any endospores present in his broths. (Anderson D. G., et al. 2016)