LECTURE 3 SPONTANEOUS GENERATION THEORY.pptx

spontaneous generation

1. MICROBIOLOGY 19BT203 UNIT I: Introduction to Microbiology: Topic-3 SPONTANEOUS GENERATION THEORY Dr. M. Indira Associate Professor Dept of Biotechnology Vignan’s Foundation for Science, Technology and Research, A.P India

2. Objective To overview the concept of spontaneous generation theory and biogenesis theory. 8/25/2022 2

3. Expected Outcome The overview of the concept of spontaneous generation theory and biogenesis theory will be known. 8/25/2022 3

4. 8/25/2022 4

5. Where do microorganism’s originate from? Spontaneous generation? What is this theory? Few day’s of being exposed to air INTRODUCTION

6. INTRODUCTION For much of history, people believed that animals could come from non-living sources. They thought: Frogs developed from falling drops of rain mice arose from sweaty underwear and flies arose from decaying meat This is called abiogenesis Also known as spontaneous generation - living organisms can develop from nonliving or decomposing matter

7. Different Theories of Spontaneous Generation Theory 1 = The spontaneous production of mice required placing sweaty clothes and husks of wheat in an open-mouthed jar, then waiting for about 21 days, during which time it was alleged that the sweat from the clothing would penetrate the husks of wheat, changing them into mice. Theory 2 = Maggots arise spontaneously in rotting meat Theory 3 = Microorganisms arise spontaneously in broth.

8. Different scientist tested theses theories over the years Francesco Redi An Italian doctor Lazzaro Spallanzani An Italian Scientist Louis Pasteur A French Scientist Spontaneous Generation

9. Jan Baptista Van Helmont The Origin of life (17 th Centuray ) Adult mice 1579-1644 Spontaneous Generation

10. Spontaneous Generation

11. Could spontaneous generation be true for microorganisms? Many believed spontaneous generation: “Life can arise from non-living matter” In 1668 , the Italian physician Francesco Redi performed an experiment to disprove spontaneous generation. Can you think of an experiment that could disprove spontaneous generation? Spontaneous Generation

12. Spontaneous Generation - Redi’s Experiment Question: where did maggots come from? Hypothesis: maggots came from the eggs of flies

13. Conditions Results 1 open jar Maggots appeared, Flies were observed on meat 1 jar covered with cheese cloth No maggots, How ever maggots developed from eggs laid by flies on cheese cloth. Flies were observed on netting 1 jar sealed with paper No maggots. No flies were observed near jar 3 From where did the maggots come? What was the purpose of the sealed jars? S pontaneous generation or biogenesis? Redi filled 3 jars with decaying meat. Spontaneous Generation

14. Conclusion: The hypothesis was supported by the data and therefore accepted Because there were no maggots in or around the jar it was concluded that the maggots came from the fly eggs. Spontaneous Generation- Redi’s Experiment

15.   John Needham (English Clergyman) wondered if this would work with microorganisms in 1745 John Needham challenged Redi's findings by conducting an experiment in which he placed a broth, or “gravy,” into a bottle, heated the bottle to kill anything inside, then sealed it. Days later, he reported the presence of life in the broth and announced that life had been created from nonlife. In actuality, he did not heat it long enough to kill all the microbes. Conclusion: He thought organic matter contained a vital force that could confer the properties of life on nonliving matter. Spontaneous Generation- John Needham Experiment

16. Question: What causes microbes to form from decaying broth? Hypothesis: Microbes come from the air. Boiling will kill microbes. Spontaneous Generation - Spallanzani’s Experiment

17. Procedure: Spallanzani put broth into four flasks Flask 1 – left open to the air Flask 2 – was sealed Flask 3 – was boiled and left open Flask 4 – was boiled then sealed Spontaneous Generation - Spallanzani’s Experiment

18. Results Flask 1 – left open to the air Turned cloudy (microbes found) Flask 2 – was sealed Turned cloudy (microbes found) Flask 3 – was boiled and left open Turned cloudy (microbes found) Flask 4 – was boiled then sealed Did not turn cloudy (NO MICROBES) Spontaneous Generation - Spallanzani’s Experiment

19. Conclusions: The hypothesis was accepted Because the combination of boiling the broth (killing bacteria that were in the jar to start) and sealing the jar (keeping bacteria in the air out) it was concluded that boiling does kill bacteria and that Microbes come from the air. Spontaneous Generation - Spallanzani’s Experiment

20. Question: Where do microbes come from to cause chicken broth to decay? Hypothesis: Microbes come from cells of organisms on dust particles in the air; not from the air itself. Biogenesis - Louis Pasteur’s Experiment

21. Spontaneous Generation of Life Life arises from non living matter The Theory of Biogenesis Life arises from pre-existing cells Biogenesis- Louis Pasteur’s Experiment

22. Pasteur’s S-shaped flask kept microbes out but let air in. These experiments form the basis of his technique. Biogenesis

23. Pasteur’s Swan neck flasks could supply air but could also trap ambient germs from entering broth Biogenesis - Louis Pasteur’s Experiment

24. 1861: Louis Pasteur demonstrated that microorganisms are present in the air. Conditions Results Nutrient broth placed in flask, heated, not sealed Microbial growth Nutrient broth placed in flask, heated, then sealed No microbial growth S pontaneous generation or biogenesis? Biogenesis- Louis Pasteur’s Experiment

25. Conclusion: The hypothesis was supported by the data therefore it was accepted. Because the broth did not turn cloudy and dust was observed trapped in the neck of the S-Shaped flask , it was concluded that the microbes came from cells of organisms riding on dust particles . Biogenesis- Louis Pasteur’s Experiment

26. 1864 - Pasteur invents pasteurization of wine. Saves the French wine industry. Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine. This application of a high heat for a short time is called pasteurization. Louis Pasteur

27. The Scientific Method Each of these scientist used the scientific method of investigation to successfully disprove spontaneous generation. Remember Science is not just a body of facts but a method of investigation . Science is a process that allows us to obtain reliable knowledge by disproving bad ideas.

28. Summary 8/25/2022 28 Spontaneous Generation of Life: Life arises from non living matter. This theory tells about the origin of life. The Theory of Biogenesis: Life arises from pre-existing cells. Different scientist tested theses theories over the years - Francesco Redi: Disproved Spontaneous generation theory. Lazzaro Spallanzani - Boiling does kill bacteria and that Microbes come from the air. Louis Pasteur- Disproved spontaneous generation theory and proposed Biogenesis theory through Scientific investigation.

29. Study Questions What is spontaneous generation theory? Describe the theories related to spontaneous generation theory? Describe the Francesco Redis Experiment? How Louis Pasteur disproved spontaneous generation theory? Describe Biogenesis theory? 8/25/2022 29

30. https://edspontaneousgeneration.weebly.com/redis-experiment.html https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Boundless)/1%3A_Introduction_to_Microbiology/1.1%3A_Introduction_to_Microbiology/1.1C%3A_Pasteur_and_Spontaneous_Generation https://courses.lumenlearning.com/microbiology/chapter/spontaneous-generation/ . https://slideplayer.com/slide/9880939/ http://people.cst.cmich.edu/swans1bj/620%20Lect%2002.pdf . https://www.alpfmedical.info/causative-agent/the-origin-of-microorganisms.html . https://microbenotes.com/louis-pasteur-and-his-contributions/ . 8/25/2022 30 References

31. "We acknowledge the online resources/public domain for using the contents to develop teaching material." 8/25/2022 31 Acknowledgement

32. THANK YOU ALL Dr. M. Indira, Associate Professor Department of Biotechnology VFSTR (Deemed To be University) Email: [email protected] 32