van Leeuwenhoek (1673)
Developed simple microscopes. First to observe microbes (wee animalcules). Father of Microbiology
Spontaneous generation
living organisms can arise from nonliving matter Ex: Moist soil toads, snakes, mice
living organisms can arise only from preexisting living organisms
Francesco Redi
set up an experiment to disprove spontaneous generation of maggots. Filled 2 jars with decaying meat, sealed one and left the other open (only the open jar developed maggots). Another experiment was set up in which a jar was covered with a fine mesh instead of being sealed so that fresh air could enter the jar (again, only the open jar developed maggots) Proved that the flies had to come in contact with the meat and lay their eggs on it, maggots did not arise spontaneously
John Needham
seemed to help prove the case for spontaneous generation by heating nutrient broth and pouring it into covered flasks (developed microbial growth) he claimed that the "vital force" had been destroyed by the heating
Lazzaro Spallanzani
he showed that broth that was heated after being put into a sealed flask did not develop microbial growth.
Louis Pasteur
1)Microorganisms can be present in nonliving matter (even in air). 2)Spontaneous generation disproved. 3)Heat can destroy microbes
who discovered Aseptic Techniques?
Pasteur. Used to prevent the contamination by unwanted microorganisms
Water purification, sewage collection and treatment
Romans developed sophisticated drinking water and sewer systems (even indoor plumbing), but these ideas were lost during the Dark Ages.Most villages, towns, and cities had problems with certain diseases due to fecal contamination of their drinking water because they lacked sewer systems. Development of good public sanitation facilities during the 18th and 19th centuries in what are now "developed" countries, drastically decreased their incidence of epidemics of cholera, typhoid and dysentery
Bassi (1830s-40s)
Perhaps the first to demonstrate a microbial cause of disease. Showed that a microscopic fungus causes a disease in silkworms. Suggested that human diseases could be caused by microbes also
Semmelweiss (1840s)
Suspected doctors/midwives were transmitting childbed fever to women during childbirth 2. Required hand washing in a chloride of lime solution. Incidence of childbed fever dropped from up to 50% to 1-3% Viciously criticized Died in exile and shame
Joseph Lister (1860s)
1. Used a disinfectant (phenol) to clean wounds, surgical dressings and instruments 2. Large decrease in wound infections 3. Concept of Asepsis (lack of germs) finally accepted
Koch (1876)
Developed pure culture techniques for growing bacteria in the lab. 2. Proved Germ Theory of Disease by showing that a specific type of bacteria causes anthrax 3. Koch's Postulates: Steps for determining the cause of any infectious disease.
Smallpox inoculation by Chinese physicians
Used intranasal inoculation of individuals with dried small pox pustules from patients with mild cases Records seem to indicate the practice started as early as the 6th century in China Became widely used in China in the 16th and 17th centuries In the 17th century, Western civilizations began to take notice
Jenner (1796)
Milkmaids who had had cowpox seemed to be protected from smallpox Showed that inoculation with material from cowpox lesions leads to immunity from smallpox (1st vaccine) 3. Steady decline in smallpox cases until eradicated in 1977
Louis Pasteur
1. Found that certain microbes that lost their ability to cause disease due to repeated culturing in the lab could be used to generate immunity Anthrax, cholera, rabies vaccines
Fleming (1928
Discovered fungi produced penicillin which killed bacteria
Chain and Florey (1941)
Showed penicillin was effective against bacterial infections in patients 1 Commercial production of penicillin - Just in time for WWII
Most drug companies stop or greatly reduce antibiotic research
Major problem with antibiotic resistant bacteria, few new antibiotics
Genetics and Molecular Biology (Avery, Macleod, and McCarty)
showed that DNA was the molecule encoding heredity
Watson and Crick
discovered the structure of DNA
developed the polymerase chain reaction (PCR)