Microbio Chapter 1

Importance of microorganisms

- most populous/diverse

- found everywhere!

- recycling

- photosynthesis

- production of food, beverages, antibiotics, and vitamins

- cause disease

Microorganisms

- organisms and acellular entities too small to be clearly seen by the unaided eye

- generally

Cellular

LIVING

- Fungi

- Protists

- Bacteria

- Archaea

Acellular

NON-LIVING

- Viruses

- Viroids

- Satellites

- Prions

Prokaryotic cells

lack a true membrane-delimited nucleus

Eukaryotic cells

have a membrane-enclosed nucleus, more complex morphologically

Three domain system

based on a comparison of ribosomal RNA genes, divides microorganisms into:

- Bacteria

- Archaea

- Eukarya

Domain Bacteria

- single-celled

- cell wall w/ peptidoglycan

- lack a membrane-bound nucleus

- live everywhere and in extreme environments!

- Cyanobacteria (produce significant amounts of oxygen!)

Domain Archaea

- unique rRNA gene sequences

- lack peptidoglycan in cell walls

- unique membrane lipids

- unusual metabolic characteristics

- live in extreme environments

Protists

unicellular and sometimes colonial eukaryotic organism that lack cellular differentiation into tissues

Fungi

Viruses

an infectious agent having a simple acellular organization with a protein coat and a nucleic acid genome, lacking independent metabolism, and multiplying only within living host cells

Viroids

an infectious agent that is a single-stranded RNA not associated with any protein; the RNA does not code for any proteins and is not translated

Satellites

Subviral infectious agents composed of DNA or RNA encapsulated with the aid of an unrelated helper virus.

Prions

an infectious agent consisting only of protein

Criteria for living organisms

1) cells and organization

2) response to environmental changes (irritability/sensitivty)

3) Growth/development

4) Biological evolution

5) Energy use and metabolism

6) regulation and homeostasis

7) reproduction

Central dogma of biology

DNA-transcription-RNA-translation-protein

RNA

believed to be the earliest molecule because it has the ability to form peptide bonds and perform cellular work/replication

Photosynthesis

the trapping of light energy and its conversion to chemical energy, which is then used to reduce CO2 and incorporate it into organic molecules

Cyanobacteria

a large group of gram-negative, morphologically diverse bacteria that carry out oxygenic photosynthesis

Universal phylogenetic tree

A phylogenetic tree that considers the *evolutionary relationships* among organism from all three domains of life: Bacteria, Archaea, and Eukarya.

Last Universal Common Ancestor (LUCA)

the most recent organism to which all extant organisms are related

Endosymbiotic Hypothesis

The hypothesis that mitochondria, and related organelles, and chloroplasts arose from bacterial endosymbionts of ancestral eukaryotic cells

Horizontal gene transfer

the process by which genes are transferred from one mature, independent organism to another

strains

a population of organisms that descends from a single organism or pure culture isolate

Eukaryotic microbes

reproduce isolated populations

Biovars

variant strains of microbes characterized by biological or physiological differences

Morphovars

A variant strain of a microbe characterized by morphological differences

Serovars

a variant strain of a microbe that has distinctive antigenic properties

Microbiology

the study of microorganisms

Francesco Stelluti

observed bees and weevils between 1625-1630

Robert Hooke

published drawings of the fungus Mucor in his book, Micrographia, in 1665

Antony van Leeuwenhoek

(1632-1723) first person to observe microorganisms accurately

- was not a scientist- he was a hobbyist!

Spontaneous generation

idea that living organisms can develop from nonliving or decomposing matter

Biogenesis

Aristotle (384-322)

History of Animals- organisms arise from elements and pneuma of material

Elements- earth, air, fire, and water

Animating force

Francesco Redi (1626-1697)

Discredited spontaneous generation

- showed that maggots on decaying meat came from fly eggs

John Needham (1713-1781)

Proponent of spontaneous generation

- experimented with cooked meat from which life arose

Lazzaro Spallanzani (1729-1799)

Reproduced Needham's experiments, but sealed the flasks

Anaximenes' (585-528) air

living things need oxygen in order to survive

Franz Schulze (1815-1873)

Reproduced Needham's experiments, passing air through a strong acid which kills most organisms

- critics suggested that acid 'altered' the air

Theodor Schwann (1810-1882)

Reproduced Needham's experiments, passing air through a heated glass tubing

- Critics suggested that Heraclitus ( 535-475) fire 'altered' the air

Heinrich Schroder and Theodor von Dusch

reproduced Needham's experiments, filtering air through cotton plug

John Tyndall

- Demonstrated that dust carries microorganisms

- showed that if dust was absent, nutrient broths remained sterile, even if exposed to air

- exceptionally heat-resistant forms of bacteria

Louis Pasteur

- Father of microbiology

- Swan-neck flask experiments (result: no growth of microorganisms- disproved spontaneous generation)

- Germ theory of fermentation

- germ theory of disease

- Pasteurization!

- rabies vaccine

Ferdinand Cohn

Heat-resistant bacteria could produce endospores

4 bodily humors

Believed to be the cause of infectious diseases

- Yellow bile

- Blood

- Black Bile

- Phlegm

The plague of Athens

- Killed 1/4 of Athens population: led to their defeat against Sparta

- Thucydides: writes about the symptoms

- Survivors became immune and cared for the ill

Roger Bacon

believed disease was caused by "invisible" beings

Girolamo Fracastoro

proposed that epidemic diseases are caused by transferable particles or "spores," which were more of a chemical than a biological form

Oliver Wendell Holmes

discovered the transmission of venereal diseases by midwives

Ignaz Semmelweis

Pioneered obstetrical procedures which reduced infections

Agostino Bassi

showed a disease of silkworms was caused by a fungus

M.J. Berkeley

demonstrated the Potato Blight of Ireland was caused by a water mold

Heinrich de Bary

showed that smut and rust fungi caused cereal crop diseases

Joseph Lister

- provided indirect evidence that microorganisms were the causal agents of disease

- developed an antiseptic surgery system which led to fewer postoperative infections

Robert Koch

- established the relationship between Bacillus anthracis and anthrax

- taught by jacob henle

Koch's 1st postulate

the microorganism must be present in every case of the disease but absent from healthy organisms

Koch's 2nd postulate

the suspected microorganism must be isolated and grown in a pure culture

Koch's 3rd postulate

the same disease must result when the isolated microorganism is inoculated into a healthy host

Koch's 4th postulate

the same microorganism must be isolated again from the diseased host

Limitations of koch's postulates

- some organims cannot be grown in pure culture

- ethical limitations

- molecular/genetic evidence could replace/overcome these limits

Koch's work led to discovery or development of:

- Agar

- Petri dishes

- Nutrient broth and nutrient agar

- methods for isolating microorganisms

Charles Chamberland

- Developed porcelain filters to study tobacco mosaic disease

- discovered that viruses are smaller than bacteria

Pasteur and Roux

incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease (termed attenuation)

Pasteur + coworkers

Developed vaccines for chicken cholera, anthrax, and rabies

Immunology

the study of a host's defenses to a pathogen

Edward Jenner

Father of immunology

- discovered small pox vaccine

- immunized James Phipps for cow pox in 1796

Emil von Behring and Shibasaburo Kitasato

developed antitoxins for diphtheria

Elie Metchnikoff

discovered bacteria-engulfing, phagocytic cells in blood

Basic aspects of microbiology

concerned with individual groups of microbes, microbial physiology, genetics, molecular biology and taxonomy

Applied aspects of microbiology

concerned with practical problems - disease, water, food and industrial microbiology

Paul Ehrlich

Chemotherapeutic agents- Salvarsanis used to treat syphilis instead of arsenic and mercury

Alexander Fleming

discovered the first antibiotic, penicillin

Molecular and Genomic methods

Led to a second golden age of microbiology

Medical microbiology

diseases of humans and animals

Public health microbiology

control and spread of communicable diseases

Microbial ecology

concerned with the relationship of organisms with their environment

Agricultural Microbiology

concerned with the impact of microorganisms on food production

Industrial microbiology

-Penicillin and other antibiotics

-Vaccines, steroids, alcohols and other solvents, vitamins, amino acids, enzymes, and biofuels

Microbial physiology

studies metabolic pathways of microorganisms

Microbial genetics

molecular biology concerned with the understanding of genetic information

Microbes

model system of genomics