History of Microbiology PDF

Microbiology Microbiology study of microorganisms that exist as single cells or cell clusters includes viruses which are microscopic but acellular Sub-disciplines Bacteriology Parasitology Virology Microbiology more than 90% of body cells are microbes about...

Microbiology Microbiology study of microorganisms that exist as single cells or cell clusters includes viruses which are microscopic but acellular Sub-disciplines Bacteriology Parasitology Virology Microbiology more than 90% of body cells are microbes about 1 kg bacteria present in average human gut 8% of human DNA is derived from remnants of viral genomes 100 million times as many bacteria in oceans (13 × 1028) as there are stars in the universe about 90% of biomass of the entire biosphere Brief History of Microbiology Early Observation Robert Hooke (1665) English scientist used compound microscope  coined the word “cells” marked the beginning of Cell Theory “all living things are composed of cells” Early Observation Early Observation Robert Hooke (1665)  coined the word “cells” able to see with a compound microscope marked the beginning of the Cell Theory  all living things are composed of cells Hooke’s microscope lacked staining Early Observation Anton van Leeuwenhoek (1632-1723) Father of Microbiology Dutch glass merchant and scientist invented the first simple microscope discovered bacteria, protists, sperm cells, blood cells - “animalcules” wrote series of letters to Royal Society of London describing what he saw through his microscope Early Observation Early Observation Spontaneous Generation Theory “life arise from nonliving matter” introduced by Aristotle (350 BC) aphids arise from dew which falls on plants fleas from putrid matter mice from dirty hay theory remained unchallenged for more than 2000 years Spontaneous Generation Debate Francesco Redi (1626- 1697) Italian physician, naturalist & poet first to formally challenge spontaneous generation theory  Spontaneous Generation Debate Redi's Question: Where do maggots come from? Hypothesis: Maggots come from flies. Experiment: Redi put meat into 3 separate jars Jar-1 Left open Maggots developed Flies were observed laying eggs on meat Jar-2 Covered with netting Maggots appeared on the netting Flies were observed laying eggs on the netting Jar-3 Sealed No maggots developed Spontaneous Generation Debate John Needham (1745) English naturalist & priest strong proponent of Spontaneous Generation Theory challenged Redi’s experiment Spontaneous Generation Debate observed that even after he heated nutrient fluids (chicken broth) cooled solutions were soon teeming with microorganisms claimed that microbes developed spontaneously from Spontaneous Generation Debate Lazzaro Spallanzani (1765) Italian scientist suggested that microorganisms from air probably had entered Needham’s solutions after they were boiled  Spontaneous Generation Debate broth heated after being sealed in flask did not develop microbial growth claimed “vital force” had been destroyed by heat & was kept out of flasks by seals Theory of Biogenesis spontaneous generation issue still unresolved in 1800s Rudolf Virchow (1858) German pathologist and statesman Living cells can arise only from Theory of Biogenesis Louis Pasteur (1861) French chemist and microbiologist demonstrated that microorganisms are present in air and that it can contaminate sterile solutions but air itself does not give rise Theory of Biogenesis – Pasteur showed that microorganisms can be present in non-living matter – on solids, in liquids, and in air. – He demonstrated that microbial life can be destroyed by heat and that methods can be devised to block the access of airborne microorganisms to nutrient environments. these discoveries form the basis of Theory of Biogenesis Theory of Biogenesis original vessels on display at Pasteur Institute in Paris still show no signs of contamination more than 100 years later Golden Age of Microbiology 1857 – 1914 establishment of microbiology as a science discoveries of agents of many diseases relationships between microorganisms & disease role of immunity in prevention and cure of disease studied chemical activities of microorganisms improved techniques for microscopy & culture of microorganisms developed vaccines & surgical Golden Age of Microbiology Fermentation & Pasteurization  group of French merchants asked Pasteur to find out why wine and beer soured when shipped long distances  many scientists believed that air converted sugars in these fluids into alcohol  Pasteur found instead that microorganisms (Yeast) convert sugars to alcohol in the absence of air.   FERMENTATION yeast sugar Golden Age of Microbiology Fermentation & Pasteurization  souring and spoiling, which occur late, are caused by a different group of microorganisms, which are bacteria  with presence of air, bacteria change alcohol in the beverage into vinegar (HAc) bacteria alcohol Vinegar/Hac (with air) Golden Age of Microbiology Fermentation & Pasteurization  FERMENTATION yeast bacteria sugar alcohol Vinegar/Hac no air with air Golden Age of Microbiology Fermentation & Pasteurization  Pasteur’s solution to spoilage  heat alcohol just enough to kill most of the bacteria  PASTEURIZATION - now commonly used to kill potentially harmful bacteria in MILK Golden Age of Microbiology The Germ Theory of Disease “specific microorganism causes specific infectious disease”  Louis Pasteur proponent of Germ Theory of Disease  1865 – silkworm disease  1835 – Agostino Bassi another silkworm disease caused by a fungus  1860s – Joseph Lister; antisepsis /antiseptic technique  1840s – Ignaz Semmelweis; father of Handwashing Golden Age of Microbiology The Germ Theory of Disease Robert Koch (1876) German scientist discovered that Bacillus anthracis produces spores & can resist adverse conditions developed method of fixing, staining & photographing bacteria developed methods of culturing bacteria on solid media discovered M. tuberculosis and V. cholerae  Golden Age of Microbiology The Germ Theory of Disease Robert Koch (1876) Koch's drawing of B. anthracis at various stages of development Golden Age of Microbiology The Germ Theory of Disease Robert Koch-1876  Vertical photomicroscopic apparatus  the type Koch used to photograph B. anthracis Golden Age of Microbiology The Germ Theory of Disease Robert Koch (1876) worked on tuberculin (protein derived from M. tuberculosis) used in skin test to diagnose TB contributed to germ theory of diseases through “Koch’s Postulates” - experimental procedure to prove that a specific microorganism causes a specific disease (1884) Golden Age of Microbiology Koch’s Postulates 1. A particular organism must be found in all cases of the disease and must not be present in healthy animals or humans. 2. The microorganisms must be isolated from the diseased animal or human and grown in a pure culture in the laboratory. 3. The same disease must be produced when microorganisms from pure culture are inoculated into a healthy susceptible laboratory animal. 4. The same microorganisms must be recovered from the experimentally infected animals and grown again in a pure Golden Age of Microbiology Koch’s Postulates Golden Age of Microbiology Koch’s Postulates Exemptions 1. Certain pathogens will not grow on artificial media. viruses, rickettsias, chlamydias Mycobacterium leprae; Treponema pallidum 2. Many pathogens are species-specific. 3. Synergistic infections are caused by combined effects of 2 or more different microorganisms. 4. Certain pathogens become altered when grown in vitro. Some become less pathogenic, while others become nonpathogenic. Thus, they will no longer infect animals after being cultured on artificial media.