THE FIRST OBSERVATIONS
• ROBERT HOOK
• FIRST TO SEE “CELLS” WHILE OBSERVING A THIN SLICE OF CORK
• MARKED THE BEGINNING OF THE CELL THEORY: THEORY THAT ALL LIVING THINGS
ARE COMPOSED OF CELLS
• ANTON VAN LEEUWENHOEK
• FIRST TO OBSERVE LIVE ORGANISMS THROUGH A MICROSCOPE
• “ANIMALCULES”
THE DEBATE OVER SPONTANEOUS
GENERATION
• AT ONE TIME MANY BELIEVED THAT SOME FORMS OF LIFE COULD ARISE
SPONTANEOUSLY FROM NONLIVING MATTER (SPONTANEOUS GENERATION)
FRANCESCO REDI
NEEDHAM AND SPALLANZANI
Needham
“Microbes
developed
spontaneously
from the fluids”
Spallanzani
Needham responded: The “virtual force” necessary
for spontaneous generation had been destroyed by
the heat and was kept out of the flasks by the seals.
THE THEORY OF BIOGENESIS
• RUDOLF VIRCHOW: CHALLENGED SPONTANEOUS GENERATION WITH
BIOGENESIS (THE CONCEPT THAT LIVING CELLS CAN ARISE ONLY FROM
PREEXISTING LIVING CELLS)
• ARGUMENTS CONTINUED UNTIL THE ISSUE WAS RESOLVED BY LOUIS
PASTEUR
LOUIS PASTEUR
LOUIS PASTEUR
• MICROORGANISMS CAN BE PRESENT IN NONLIVING MATTER
• MICROBIAL LIFE CAN BE DESTROYED BY HEAT
• METHODS CAN BE DEVISED TO BLOCK THE ACCESS OF AIRBORNE
MICROORGANISMS TO NUTRIENT ENVIRONMENTS
• FORM THE BASIS OF ASEPTIC TECHNIQUES
• PREVENT CONTAMINATION BY UNWANTED MICROORGANISMS
• ANY APPEARANCE OF “SPONTANEOUS” LIFE IN NONLIVING SOLUTIONS
CAN BE ATTRIBUTED TO MICROORGANISMS THAT WERE ALREADY
THERE
ROBERT KOCH
• FIRST PROOF THAT BACTERIA CAUSE DISEASE
• ESTABLISHED A SEQUENCE OF EXPERIMENTAL STEPS FOR DIRECTLY RELATING
A SPECIFIC MICROBE TO A SPECIFIC DISEASE: KOCH’S POSTULATES
FERMENTATION & PASTEURIZATION
• PASTEUR FOUND THAT MICROORGANISMS CALLED YEASTS CONVERT THE
SUGARS IN ALCOHOL IN THE ABSENCE OF AIR (FERMENTATION)
• USED TO MAKE WINE AND BEER
• SOURING AND SPOILAGE ARE CAUSED BY BACTERIA. BACTERIA CHANGE THE
ALCOHOL INTO VINEGAR (ACETIC ACID)
• PASTUER’S SOLUTION: HEAT THE BEER AND WINE JUST ENOUGH TO KILL MOST
OF THE BACTERIA THAT CAUSED THE SPOILAGE (PASTEURIZATION)
THE GERM THEORY OF DISEASE
• IDEA THAT MICROORGANISMS CAUSE DISEASE
• AGOSTINO BASSI: MADE 1ST ASSOCIATION BETWEEN A MICROORGANISM AND
A DISEASE BY PROVING THAT A FUNGUS WAS THE CAUSE OF A SILKWORM
DISEASE
• PASTUER FOUND THAT ANOTHER SILKWORM DISEASE WAS CAUSED BY A
PROTOZOAN
JOSEPH LISTER
• APPLIED GERM THEORY TO MEDICAL PROCEDURES
• BEGAN TREATING SURGICAL WOUNDS WITH A PHENOL SOLUTION (KNOWN TO
KILL BACTERIA)
• REDUCED INFECTIONS AND DEATHS AND SOON ADOPTED BY OTHER
SURGEONS
VACCINATION
• EDWARD JENNER SHOWED THAT THE MILD DISEASE COWPOX GAVE
IMMUNITY TO SMALLPOX
• INOCULATED PEOPLE WITH COWPOX MATERIAL BY SCRATCHING THEIR ARM
WITH A COWPOX-INFECTED NEEDLE
• BECAME KNOWN AS VACCINATION
• IMMUNITY: PROTECTION FROM DISEASE THAT VACCINATION PROVIDES
• PASTEUR THEN SHOWED WHY VACCINATIONS WORK
THE BIRTH OF MODERN CHEMOTHERAPY:
DREAMS OF A MAGIC BULLET
• CHEMOTHERAPY: TREATMENT OF DISEASE BY CHEMICAL SUBSTANCES
• SYNTHETIC DRUGS: PREPARED FROM CHEMICALS IN A LABORATORY
• ANTIBIOTICS: PRODUCED NATURALLY BY BACTERIA AND FUNGI
• PAUL EHRLICH: SPECULATED ABOUT A “MAGIC BULLET” THAT WOULD
DESTROY A PATHOGEN WITHOUT HARMING THE HOST
• FOUND SALVARSAN, AN ARSENIC DERIVATIVE THAT WAS EFFECTIVE AGAINST
SYPHILIS
THE BIRTH OF MODERN CHEMOTHERAPY:
DREAMS OF A MAGIC BULLET
• FIRST ANTIBIOTIC DISCOVERED BY ACCIDENT
• ALEXANDER FLEMING OBSERVED THE INHIBITION OF BACTERIAL GROWTH BY
THE MOLD Penicillium notatum.
• THE INHIBITOR (PENICILLIN) WAS MASS PRODUCED AND CLINICALLY TESTED
IN THE 1940S.
MODERN DEVELOPMENTS IN
MICROBIOLOGY
• BACTERIOLOGY: THE STUDY OF BACTERIA
• MYCOLOGY: THE STUDY OF FUNGI
• PARASITOLOGY: THE STUDY OF PROTOZOA AND PARASITIC WORMS
• IMMUNOLOGY: THE STUDY OF IMMUNITY
• VIROLOGY: THE STUDY OF VIRUSES
RECOMBINANT DNA TECHNOLOGY
• GENETIC ENGINEERING
• BACTERIA PREFERRED BECAUSE OF THEIR SIMPLICITY AND RAPID
REPRODUCTION RATE
• MICROORGANISMS CAN NOW BE GENETICALLY ENGINEERED TO MANUFACTURE
LARGE AMOUNTS OF HUMAN HORMONES & OTHER MEDICAL SUBSTANCES
• FRAGMENTS OF HUMAN OR ANIMAL DNA CAN BE ATTACHED TO BACTERIAL DNA
• WHEN INSERTED INTO BACTERIA, IT CAN BE USED TO MAKE LARGE QUANTITIES OF
THE DESIRED PROTEIN
Recycling
Vital
Elements
(CO2, N)
Sewage
Treatment
Microbes
& Human
Welfare
Insect Pest
Control
Bioremediation
(clean up
pollutants)
MICROBES & HUMAN DISEASE
• NORMAL MICROBIOTA (FLORA): THE MICROORGANISMS THAT COLONIZE A
HOST WITHOUT CAUSING DISEASE
• DO NOT HARM US….MAY BENEFIT US
•
•
PREVENT GROWTH OF HARMFUL MICROBES
PRODUCE USEFUL SUBSTANCES (VITAMINS)
• THE DISTINCTION BETWEEN HEALTH AND DISEASE IS PART OF A BALANCE
BETWEEN THE NATURAL DEFENSES OF THE BODY AND THE DISEASEPRODUCING PROPERTIES OF MICROORGANISMS
• DEPENDS ON OUR RESISTANCE (THE ABILITY TO WARD OFF DISEASES)
INFECTIOUS DISEASES
• PATHOGENS INVADE A SUSCEPTIBLE HOST AND CARRY OUT AT LEAST PART OF
THEIR LIFE CYCLE IN THAT HOST
• EMERGING INFECTIOUS DISEASES: NEW OR CHANGING DISEASE THAT IS
INCREASING OR HAS THE POTENTIAL TO INCREASE IN THE NEAR FUTURE