Chapter 1, Problem 1AQ

Pasteur’s experiments on spontaneous generation contributed to the methodology of microbiology, understanding of the origin of life, and techniques for the preservation of food. Explain briefly how Pasteur’s experiments affected each of these topics.

Summary Introduction

To explain:

How Pasteur’s experiments affected the methodology of microbiology, origin of life, and food preservation techniques.

Concept introduction:

Louis Pasteur is a French microbiologist, who, having renowned discoveries of microbial fermentation, pasteurization, and vaccination. Pasteur is the responsible person for disproving the spontaneous generation. He conducted many experiments related to microbial contaminations. Pasteur’s vaccine discovery reduces the mortality rate of rabies and anthrax.

Explanation of Solution

Louis Pasteur defeated the spontaneous generation theory by swan necked experiment. He strongly believed that the microorganisms were already present in the environment. So, he conducted some experiments to eliminate or kill the contaminating microorganisms by sterilization technique.

In Spallanzani’s experiment, Louis Pasteur used modified glass flask with a curved neck. This flask is filled with broth and heated. The entry of microorganisms are prevented due to the curved neck of the flask and the heated broth remained clear. When the curved neck of the flask was broken, the broth became contaminated with microorganisms with a cloudy appearance. From this, Pasteur concluded that the contamination arose only because of entry of air particles. Thus, this principle of biogenesis became the leap of the biology history.  

Louis Pasteur experiments on spontaneous generation were contributed to the methodology of microbiology, origin of life understanding, and various techniques for food preservation. Alcohol fermentation is considered as the major contribution of Pasteur in the methodology of microbiology. In this, he introduced optimal methods for the enhanced fermentation of beer and other juices. He found that the yeast cells are responsible for catalyzing the alcoholic fermentation. He also worked on the metabolism of tartrate.

After the discoveries of fermentation, Pasteur opposed the spontaneous generation. He gave the concept the putrefying substances in the air and conducted a swan-necked or ‘S’ flask called Pasteur flask. The Pasteur flask was filled with nutrient solution and sterilized by heating. The heating process did not allow the entry of air, dust and microbes and it ensured the sterile nutrient solution. The air particles which had bacteria were trapped in the bend neck of the flask and it could not enter even when the flask was cooled down. The results of this experiment were inconsistent with the theory of spontaneous generation because “fresh air was not needed for the phenomenon to occur. Thus, Louis Pasteur defeated the theory of spontaneous generation by conducting a swan-necked flask experiment for sterilization.

Pasteur also gave a concept of sterilization- a process of removing and killing of microbes or contaminants from an object. He also worked on several sterilization techniques that were used in basic science and microbiology field. Pasteurization is one of major contribution on food microbiology for food preservation. It is a process of heating a liquid to destroy or eliminate the harmful pathogens including enzymes that are responsible for spoilage. This prevents the cause of spoilage as well as the souring. Today, pasteurization technique is regularly used in dairy and food industries for checking the control of microbes and food preservation.