Microbiology is the study of microorganisms. This entails their reproduction, growth, survival, and most important mechanisms by which they cause disease. These organisms cause diseases in plants, animals, and humans. As such, a proper understanding of their characteristics is crucial in controlling them.
Three major theories have been suggested to explain the origin of microorganisms. The uni-vocal theory which is the most accepted purports that an organism originates from a parent of the same species. The equivocal theory suggests that an organism can originate from a completely unrelated organism. The spontaneous theory suggests that these organisms arise from non-living things. It was proposed by Aristotle and was widely accepted at the time because microbiological study techniques were not yet fully advanced. Most scholars particularly accepted this theory because it explained the presence of maggots in food products especially meat (Parke, 2014).
With time, this theory faced criticism, and the other two theories were accepted more. In 1668, Francesco Redi carried out an experiment to discredit the spontaneous theory. He placed chunks of meat in three different jars. The first was left open, flies found their way in and laid eggs which hatched to the maggots that were seen. The second was stoppered by a gauze that stopped flies from entering, but their eggs may have dropped into the jar and formed maggots. The third jar was wholly sealed. Maggots were absent in this jar (Parke, 2014).
In 1859, Louis Pasteur boiled culture broth in three separate flasks to kill any microorganisms present then left them to cool and in the process, let fresh air flow in (Geison, 2014). One flask was left open; the second was covered with cotton wool while the other was connected to a sterilant that removed bacteria present in the air getting in. At the end of the experiment, the third jar had no maggots at all (Geison, 2014).
Spontaneous generation does not therefore accurately explain the origin of microbes. Biogenesis which explains that organisms arise from other existing forms of life is more widely accepted in microbiology.
Geison, G.L. (2014). The Private science of Louis Pasteur. Princeton University Press.
Parke, E.C. (2014). Flies from meat and wasps from trees: Reevaluating Francesco Redi’s spontaneous generation experiments. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences, 45, 34-42.