history and scope of microbiology

HISTORY AND SCOPE OF MICROBIOLOGY

History• 1665 Robert Hooke observed

living plant tissues (20X mag.)

• “Little boxes” or Cells• Used simple magnifying lens• Suggested all living things

are made of cells

Hooke's Microscope

1665

Antonie van Leeuwenhoek was inspired by this publication

Antonie van Leeuwenhoek(1677) (“layu-wen-hook”)

–First observation of living cells (200-300X mag.)

–“Animalcules”–Single lens Microscope (Self

made)—simple microscope–Tooth plaque–Rain water–Diarrheal feces

Antonie van Leeuwenhoek• Bacteria• Protozoa• Sperm cells• Blood cells• Microscopic

worms

Antonie van Leeuwenhoek’smicroscope

3-4” microscope

Required good lighting and patience

Spontaneous Generation• The idea that life could arise

spontaneously from nonliving matter–Ex: Toads and Mice could arise from soil

–Until the 18th century this believe existed

History (cont.)• 1668 Francesco

Redi–1st one to disprove spontaneous generation

Francesco Redi’s experiments with meat

uncovered covered

Maggots No maggotsDisproved that maggots arise from decaying meat!!

• Proved (??) spontaneous generation in chicken broth

• Heated Nutrient Fluids and poured them into covered flasks

British clergyman John Needham’s experiments (1745)

Hot Mutton gravy

Turbid broth

“...my phial swarm’d with life...”

Italian priest Lazzaro Spallanzani (1765)

• Similar to Needham’s Experiments

• He showed that heating a sealed flask of meat broth prevented growth of organism

• Skeptics claimed—lack of O2 prevented growth!!

The Golden Age of Microbiology!

•Louis Pasteur (finally disproved spontaneous generation after many years of debate)

•Robert Koch (proof of germ theory)

•Other pioneers in Microbiology

Pasteur—Father of microbiology

•1857- Louis Pasteur saves France’s wine industry•Napoleon III begged Pasteur (a chemist by training) to help solve a problem•Sailors were mutinying b/c their wine was spoiling after only a few weeks at sea•Pasteur armed with his trusty microscope accepted the challenge

Luis Pasteur

–Spontaneous Generation finally disproved

–Boiled broth in long-s-shaped necked flasks (unsealed)•Remained sterile•Proved that microorganisms are present in air, but air does not create microbes

–Beginning of the golden age of microbiology

Louis Pasteur (1861)

Swan neck flask experiment disproved spontaneous generation(1861)

History (cont.)• 1861 Pasteur

–Proved Microorganisms are present in nonliving matter

–Microbes can be destroyed by heat

•Aseptic Technique• Fermentation mediated by yeast, not air

–Pasteurization to prevent wine and beer spoilage (by bacteria)

1857-Louis Pasteur saves France’s wine

1)Good wine contained yeast

2)Sour wine contained bacterium (Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid).

3)He reasoned that if wine is heated to destroy the harmful bacteria it wouldn’t spoil (process known as Pasteurization)

Pasteur’s Tomb in the Crypt of the Pasteur Institute in Paris

Germ Theory of Disease

• Pasteur proposed that wine spoiling in an analogy for disease (bacterial growth made the wine “sick”)

• He hypothesized in 1857 that microorganisms are responsible for infectious diseases

Edward Jenner (country doctor)–Milkmaid didn’t get smallpox b/c they contracted the

milder form of cowpox–Immune system cannot distinguish btw

cowpox/smallpox–Scratched a farmboy w/ a needle bearing fluid from

cowpox–Small pox Vaccine- -Vacca-cow- Vaccination w/ cowpox provided immunity for

smallpox

Protection from a disease from vaccination

Immunity

Robert Koch (1843-1910)

• German country physician who developed microbiology into a science

• Developed pure culture techniques (used potato slices to grow bacteria) developed agar later on

• Proof of the germ theory• Work with anthrax• Koch’s postulates

Bacillus anthracis

Pure Culture Key to Studying Microbes

Definition: Pure culture is a population of organism, all of which are the progeny of a single organism

-In nature, microbes almost never occur as pure cultures

AGAR•Is a complex polysaccharide derived from seaweed•Was suggested by Fannie Hesse wife of Koch’s co-worker Walther Hesse•“why do your jellies and pudding stay solid in warm weather”?

•AGAR-AGAR had been used as a gelling agent in Asia for centuries•Fannie learned to use AGAR-AGAR from a Dutch neighbor in New York who spent time in Asia

Koch’s postulates1)Specific microorganism is present in all

cases of the disease2)Organism can be obtained in pure

culture outside of the host3)Organism when re-inoculated into host

causes the same symptoms4)Organism can be isolated in pure culture

from experimentally infected host

Koch’s findingsKoch and his coworkers discovered that bacteria caused•TUBERCULOSIS•CHOLERA•DIPTHERIA•TYPHOID FEVER•GONORRHEA•PNEUMONIA

Hungarian doctor Ignaz Semmelweis (1818-1865)

• Taught medicine in Vienna• No one connected germs w/ disease yet• Puerperal fever “childbirth fever”

caused 25-30% mortality• Nearby obstetric hospital had only a

2% death rate

Ignaz Semmelweis (cont.)• He made some observations• Medical Students working on

cadavers moved from the dissecting room to the maternity ward

• Midwives –Stayed only in maternity ward

Ignaz Semmelweis (cont.)

• Ordered students to wash hands and medical instruments in chlorinated lime

• Mortality dropped to 1.3%• By 1848, 0% mortality

Paul Ehrlich-hospital dermatologist

• Chemotherapy-Treatment using chemical substances

• 1910 Paul Ehrlich -”Magic bullet”

–Salvarsan (arsenic derivative)•Preparation 606

–Syphilis

Alexander Fleming –scottish researcher--1928

• Discovered Penicillin (fungus) by accident• Was convinced that nasal mucus had

antibacterial effects• Left his Staphylococcus culture on an agar

plate for 2 weeks-went on vacation-came back &found mold on his plate which prevented bacterial growth (a mycology lab underneath him had this rare spore drift)

Founders of Microbiology (Review)

•First observed microbes—Leeuwenhoek

•Proved living cells can arise only from other living cells---Pasteur

•Confirmed the Germ Theory of Disease --Koch

Scope of microbiology

Microbiology

• Bacteria• Fungi• Viruses• Immunology

Bacteria• Medical importance

–Gastroenteritis–Syphilis–Tetanus–Lyme disease–Plague

Bacteria (cont.)• Industrial importance

–Food supplements•Amino acids & Vitamins

–Organic solvents•Acetone

Bacteria (cont.)

• Pharmaceutical importance–Antibiotics

•polymyxin–Hormones

•Insulin

Biotechnology and Recombinant DNA

• Biotechnology:–The use of microorganisms, cells, or

cell components to make a product

–Foods, antibiotics, vitamins, enzymes• Recombinant DNA Technology:

–Insertion or modification of genes to produce desired proteins

Figure 9.1.1

Bacteria (cont.)• Environmental importance

–Biodegradation

•Oil spills

•Wastewater treatment

Figure 9.1.2

Gram positiveS. aureus

Gram negativeE. coli

Fungi

• Medical importance–Valley fever

–Candidiasis

–Athlete's foot

Fungi (cont.)• Industrial importance

–Fermentation•Wine•Beer•Bread

Fungi (cont.)

• Pharmaceutical importance–Antibiotics

•Penicillin

Fungi (cont.)

• Environmental importance–Wastewater treatment

–Degradation of complex organic matter

•Lignin in wood

Viruses

• Medical importance–HIV–Influenza–Rabies –Common cold

Viruses

• Genetic engineering–“Gene shuttles”

–Treatment of some genetic disorders

• Microinjection• Gene gun

DNA can be inserted into a cell by:

Figure 9.6 & 7

Viruses (cont.)

• Environmental importance–Unknown

ADENOVIRUS

HERPESVIRUS

• West Nile encephalitis

–West Nile Virus

–First diagnosed in the West Nile region of Uganda in 1937.

–Appeared in New York City in 1999.

Emerging Infectious Diseases

• Bovine Spongiform Encephalopathy

– Prion (infectious proteinaceous material)

– Also causes Creutzfeldt-Jakob disease

(CJD)

– New-variant CJD in humans related to

cattle fed sheep offal for protein.

Emerging Infectious Diseases

• Escherichia coli O57:H7

–Toxin-producing strain of E. coli

–Fist seen in 1982

–Leading cause of diarrhea worldwide.

Emerging Infectious Diseases

• Invasive group A Streptococcus

–Rapidly growing bacteria cause extensive tissue damage.

–Increased incidence since 1995

Emerging Infectious Diseases

• Ebola hemorrhagic fever

–Ebola virus

–Causes fever, hemorrhaging, and blood clotting

–First identified near Ebola River, Congo

–Outbreak every few years

Emerging Infectious Diseases

• Hantavirus pulmonary syndrome

– Hantavirus

– Fist identified in 1951 in Korea as cause of hemorrhagic fever and named for Hantaan River

– A new disease involving respiratory symptoms was seen in the U.S. in 1995

– The U.S. virus, called Hantavirus Sin Nombre virus, probably came to the U.S. with rats around 1900

Emerging Infectious Diseases

• Acquired immunodeficiency syndrome (AIDS)

– Human immunodeficiency virus (HIV)

– First identified in 1981.

– Worldwide epidemic infecting 40 million people; 14,000 new infections everyday.

– Sexually transmitted disease affecting males and females.

– In the U.S., HIV/AIDS in people 13-24 years of age: 44% are female and 63% are African American.

Emerging Infectious Diseases

• Anthrax

– Bacillus anthracis

– In 1877, Koch proved B. anthracis causes anthrax.

– Veterinarians and agricultural workers are at risk of cutaneous anthrax.

– In 2001, dissemination of B. anthracis via mail infected 22 people.

Emerging Infectious Diseases