Paper I
Question
Louis Pasteur
Answer
Louis Pasteur (1822–1895), a French chemist and microbiologist, is regarded as one of the founding fathers of modern microbiology, for several landmark contributions:
- Disproved spontaneous generation — his swan-neck flask experiments demonstrated that microbial growth in a sterile nutrient broth arises only from microorganisms already present in air/dust, not spontaneously from non-living matter, establishing the germ theory on a firm experimental footing.
- Pasteurization — developed the process of heating liquids (originally wine, later applied to milk) to a temperature sufficient to kill pathogenic and spoilage organisms without significantly altering the product’s quality; still in routine use for milk today (holder method 63°C/30 min; flash/HTST 72°C/15–20 sec).
- Principle of attenuation and the concept of vaccination — showed that a pathogen’s virulence could be artificially weakened (attenuated) by serial passage or altered growth conditions, and that inoculation with such attenuated organisms could confer protective immunity without causing full-blown disease; on this principle he developed vaccines against fowl cholera, anthrax (public demonstration at Pouilly-le-Fort, 1881), and, most famously, rabies (first human rabies vaccine, 1885 — used successfully post-exposure on Joseph Meister).
- Coined the term “vaccine” in honour of Edward Jenner’s earlier cowpox (vacca = cow) work, extending the concept beyond smallpox to any attenuated-organism immunization.
- His work laid the foundation for aseptic technique in surgery and industrial fermentation science.