Introduction to Microbiology

Introduction to Introduction to MicrobiologyMicrobiology

Dr. Carmen RexachDr. Carmen RexachMt San Antonio CollegeMt San Antonio College

MicrobiologyMicrobiology

What are microbes?

Three empires

BACTERIA

ARCHAEA

EUKARYA

Microbes include:

• Bacteria– Kingdom Prokaryotae (Monera)– Kingdom Archaea

• Protozoans– Kingdom Protista

• Fungi– Kingdom Fungi

• Algae– Kingdom Protista or Plantae

• Multicellular parasites– Kingdom Animalia

Characteristics of life

• Nutrition (self-feeding)• Self-replication (growth)• Differentiation • Chemical Signaling (response to stimuli)• Evolution (natural selection)

Viruses will also be discussed….but they aren’t considered to be alive, even though we classify them as microbes!

The role of microbes

• Decomposers, nutrient recycling

Clover root with Rhizobium nodules

The role of microbes: commercial uses

• Synthesis of chemical products• Foods• Agriculture

Commercial uses

• Biotechnology

Bioreactor and vaccine production

Commercial uses

• Bioremediation

Even though most microbes are harmless

and are important contributors to a healthy

world, we tend to associate them most often with disease!

Even though most Even though most microbes are harmless microbes are harmless

and are important and are important contributors to a healthy contributors to a healthy

world, we tend to world, we tend to associate them most associate them most often with disease!often with disease!

Pathogen: Parasite that does harm to the host

Emerging infectious diseases• Tuberculosis• Hepatitis C• Malaria• Enterohemorrhagic E. coli (0157:H7)• Lyme Disease• Influenza• Hantavirus pulmonary syndrome• AIDS• CJD/BSE• Nipah virus• Foot and Mouth Disease• West Nile Virus• SARS• Zika virus

Why are infectiousWhy are infectiousdiseases still a problem diseases still a problem today?today?

Bacteria are ubiquitous• Aseptic technique: exclude

contaminants, prevent accidental inoculation of ourselves and others

• Try to minimize airborne contaminants

HISTORY OF INFECTIOUS DISEASE

AND GERM THEORY

HISTORY OF HISTORY OF INFECTIOUS DISEASE INFECTIOUS DISEASE

AND GERM THEORYAND GERM THEORY

Ancient History• Association between

sanitation and disease– First toilets on Crete,

India, Pakistan, Scotland 2800 BC

– Rome: Public lavatories with running water AD 315

– Chinese invented toilet paper in AD 589

– Punishment for pollution of water supply in ancient Rome was death

Ancient History• Recognition that some diseases were

communicable– Shunning of lepers– Abandonment of communities during plague

epidemics– Recognition that previously infected individuals

did not get disease again– Biblical rules and regulations for disposal of human

waste– Malaria – Pontine marshes

• The leper who has the disease shall wear torn clothes and let the hair of his head hang loose, and he shall cover his upper lip and cry, `Unclean, unclean.' He shall remain unclean as longas he has the disease; he is unclean; he shall dwell alone in a habitation outside the camp. – Leviticus 13: 45-56

AD 300 first accurate description of leprosy by Sursuta, an Indian physician

History• Hieronymus Fracastorius (1483-1553) from Verona

– Trained in medicine, geology, philosophy– De Contagione

• described seeds of disease• Could be spread by direct contact, fomites,

distance (air and water)• This was first proposal of germ theory, 300 years

before it was formulated by Pasteur and Koch!

Invention of the microscope• Robert Hooke (1665)

– Cells= smallest units of life– Beginning of cell theory

RobertHooke

Invention of microscope• Anton von Leewenhoek (1673-1723)

– Magnifying lenses– Animalcules

• Bacteria from teeth– Believed they arose from rotting gums

• Sperm, Giardia– Royal Society of London

Spontaneous generation: debate

• Francesco Redi (1626-97)• John Needham (1745)• Lazzaro Spallanzani (1729-1799)• Rudolf Virchow (1858)• Louis Pasteur (1822-95)

Sequence of events• Francesco Redi

– Maggots and raw meat– “Omne vivum ex ovo”

• John Needham– Boiled broth left open to the

environment generates microbes• Lazzaro Spallanzani

– Sealed flasks produced no microbes: disputed Needham’s findings

Needham and Laurent Lavoisier respond: there can be no life without oxygen!

Sequence of events

• Rudolf Virchow (1821-1902)– German pathologist– Biogenesis = “omni cellula

a cellula”– Published in 1858– Did not believe in germ

theory

Louis Pasteur (1822-1895)• Swan-necked flask• Basis of aseptic technique

John Tyndall• Supported Pasteur’s position against

spontaneous generation• Spores• Developed “tyndalization”

– Heating media to bp at normal atmospheric pressure over successive days to destroy spores

– Useful when autoclave is unavailable

The presence of spores in Pasteur’s experiment would have given him entirely different results! Great discoveries are often the results of LUCK!

Golden Age of Microbiology (1857-1914)

• Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs

Golden Age of Microbiology

• Fermentation and pasteurization– Pasteur

• Merchants concerned about beer/wine spoilage

• Fermentation= anaerobic process; spoilage caused by aerobic bacteria

• Developed heat pasteurization– Vat temperatures raised to 60oC

– Pasteurization• Still used today!• What happened when E.coli 0157:H7 was

found at Odwalla?Louis Pasteur

Germ theory of disease

• People used to think that diseases were a punishment

• How did we determine that there was link between microbes and disease?

Germ theory

• Agostino Bassi (1835)• Ignaz Semmelweis (1840)• Joseph Lister (1860)• Robert Koch (1876)

Agostino Bassi (1835)

• Italian entomologist• Determined cause of a

silkworm disease by using the microscope and observing fungus

• Set the stage for Pasteur’s discovery of protozoal agent of another silkworm disease

Ignaz Philip Semmelweiss(1818-65)

• Assistant at First Obstetric Clinic, AllgemeinesKrankenhaus, Vienna

• Clinics training physicians had higher rate of puerpural fever than those training nurse midwives…why?

Semmelweiss and handwashing

midwives dinner

physiciansDissecting

room

Putridparticles

Joseph Lister (1827-1912)

• Professor of Surgery, Glasgow Royal Infirmary

• Used phenol (carbolic acid) to sterilize surgical wounds

• Demonstrated that microbes caused wound infections

Robert Koch (1843-1910)

• Received MD 1862• Started by studying

anthrax in cattle/sheep• Enormous contributions

to microbiology• Winner Nobel Prize

1905 in Physiology and Medicine

Koch’s contributions• Demonstrated association between disease

and microbes• Established importance of lab cultures• Concept of pure culture• Specific organisms had specific effects• Discovered M. tuberculosis & developed

acid-fast stain• Discovered V. cholera & method for ID in

water• First photomicrographs of bacteria

Pure culture

• Developed methods via single colonies on solid medium

• Specific size, shape, color of each colony

• Fannie Hess and agar– Wife of graduate student

• Julius R. Petri and the Petri dish

Koch’s postulates• Koch’s postulates

– 1. Organism should be constantly present in diseased animal and not in the healthy

– 2. Must be able to isolate organism in pure culture

– 3. Inoculation of healthy animal with culture must initiate disease symptoms

– 4. Must be able to reisolate organism from experimental animals, culture, and again see same organism

Edward Jenner (1749-1823)

• British physician developed small pox vaccine 70 years before Koch

• Milkmaids and cowpox• Cow pox blisters

inoculated into healthy “volunteers” = immunity

• Later called vaccine from “vacca”

Variolation• Basis for Jenner’s vaccine• Described by Buddhist nun

in China in AD 1022– Grind up smallpox scabs and

blow into nose of non-immune individual to induce immune response

– Called variolation because the small pox virus is called Variola

Vaccines: Pasteur (1880-1890)

• Avirulent microbes stimulate immune response

• Development of vaccines for anthrax, chicken cholera, rabies– Developed method for attenuation

Modern Chemotherapy: synthetic drugs

• Paul Ehrlich (1854-1915)– German doctor doing

research on aniline dyes– Looking for magic bullet to

selectively target microbes• First drug: salvarsan (for

syphillis)• Later developed “neosalvarsan”• These were sulfa drugs, used

extensively in the 1930’s

Antibiotics

• Alexander Fleming (1881-1955)– Scottish doctor– Contaminated culture plates

left unattended– Inhibition of bacterial growth– Isolated Penicillium notatum

• Unaware of applications

• Renee Dubois (1939)– Discovered Gramicidin,

tyrocidine– Kindled interest in applications

for penicillin

Today: Problems of resistance

Modern Developments in Microbiology

• Bacteriology = study of bacteria.• Mycology = study of fungi.• Parasitology = study of protozoa and

parasitic worms.• Genomics provide tools for

reclassifying microorganisms

Modern Developments in Microbiology

• Immunology =study of immunity– Vaccines and interferons to

prevent and cure viral diseases.– Can be used for identification of

bacteria, viruses, toxins, etc.• Serotyping (variants within a

species) proposed by Rebecca Lancefield in 1933

• Agglutination assays• ELISA’s• Etc.

Figure 1.4 (3 of 3)

Modern Developments in Microbiology

• Virology = study of viruses.• Recombinant DNA technology

– Paul Berg (1960) produced recombinant inserting animal DNA into bacterium producing animal protein

– Recombinant DNA technology (genetic engineering) involves microbial genetics and molecular biology

Modern Developments in Microbiology

• Using microbes– George Beadle and Edward Tatum showed

that genes encode a cell’s enzymes (1942).

– Oswald Avery, Colin MacLeod, and MaclynMcCarty showed that DNA was the hereditary material (1944).

– Francois Jacob and Jacques Monod discovered the role of mRNA in protein synthesis (1961).

1901* von Behring Diphtheria antitoxin1902 Ross Malaria transmission1905 Koch TB bacterium1908 Metchnikoff Phagocytosis1945 Fleming, Chain, Florey Penicillin1952 Waksman Streptomycin1969 Delbrück, Hershey, Luria Viral replication1987 Tonegawa Antibody genetics1997 Prusiner Prions

Selected Nobel Prizes in Physiology or Medicine

Biological Insecticides• Microbes used to destroy insect pests• Bacillus thuringiensis (BT) fatal in many

insects, harmless to other animals, including humans, and to plants.

• Remember the Taco Bell incident???

Normal microbial flora and health

• Humans and other organisms are colonized with bacteria

• Bacteria play a major role in health– Colony resistance– Stimulation of immune response

• Presence of low level cross-reactive antibodies• Stimulate development of Peyer’s Patches

– Production of essential products• Vitamin K & Vitamin B12