Microbiology 155Chapter 1

An Introduction to the World of Microbiology

1. Archaebacteria

Archaebacteria – Very small bacteria that are adapted to extreme conditions

Thermophiles- extreme heatHalophiles – high concentrations of saltMethanogens – live in a hostile environment

and produce methane gas as a by product of their life style

Sulfur loving bacteria – live in high concentrations of sulfurous gases

2. Bacteria

• Eubacteria – True bacteria – Includes environmental bacteria such as nitrogen fixing bacteria and bacteria of decay and decomposition as well as pathogens.

• Cyanobacteria – Formerly known as blue green algae – small, unicellular algae found in ponds, lakes, streams, and the ocean. Essential to the web of life

Prokaryote cells

•Are very small and undifferentiated

• Lack a nuclear membrane

• Lack cellular organelles like mitochondria

• Have unique cell walls and cell membranes

• Have only one circular chromosome

Bacterial Growth= Cell Division

Binary fission

Bacterial cells can be seen with a light microscope or an electron

microscope

3. Eukarya

• Includes• Protozoans• Algae• Fungi• Animals and Plants

Algae

Eukaryote cells with cellulose cell wall

Aquatic environment

Microbes that Cause Disease

• Viruses- acellular• Bacteria• Fungi• Protozoans• Worms( Helminths )

Viruses

Blepharisma, large protozoan

Paramecium Amoeba

Malaria

Schsiotosomes, a parasitic worm

Candiasis, yeast

Historical Roots of Microbiology

1660: Robert Hooke (1635-1703) published "Micrographia", containing drawings and detailed observations of biological materials made with the best compound microscope and illumination system of the time. 1676: Anton von Leeunhoek (1632-1723) was the first person to observe microorganisms. 1883: Carl Zeiss pioneered developments in microscopy (such as immersion lenses and apochromatic lenses which reduce chromatic aberration) which perist until the present day. 1931: Ernst Rusko -constructed the first electron microscope.

1688: Francesco Redi (1626-1678) was an Italian physician who refuted the idea of spontaneous generation by showing that rotting meat carefully kept from flies will not spontaneously produce maggots. 1836: Theodor Schwann (1810-1882) helped develop the cell theory of living organisms, namely that that all living organisms are composed of one or more cells and that the cell is the basic functional unit of living organisms. 1861: Louis Pasteur (1822-1895) famous experiments with swan-necked flasks finally proved that microorganisms do not arise by spontaneous generation.

Redi’s Experiment

Edward Jenner

1546: Hieronomus Fracastoro (Girolamo Fracastoro) wrote "On Contagion" ("De contagione et contagiosis morbis et curatione"), the the first known discussion of the phenomenon of contagious infection. 1835 Agostino Bassi de Lodi showed that a disease affecting silkworms was caused by a fungus - the first microorganism to be recognized as a contagious agent of animal disease. 1847: Ignaz Semmelweis (1818-1865), a Hungarian physician who decided that doctors in Vienna hospitals were spreading childbed fever while delivering babies. He started forcing doctors under his supervision to wash their hands before touching patients. 1857: Louis Pasteur proposed the "germ theory" of disease. 1867: Joseph Lister (1827-1912) introduced antiseptics in surgery. By spraying carbolic acid on surgical instruments, wounds and dressings, he reduced surgical mortality due to bacterial infection considerably

Lister’s Carboxylic spray

Sterile Surgery

Pasteur Fermentation

Beer and Bread

1876: Robert Koch (1843-1910). German bacteriologist was the first to cultivate anthrax bacteria outside the body using blood serum at body temperature. Building on pasteur's "germ theory", he subsequently published

"Koch's postulates" (1884), the critical test for the involvement of a microorganism in a disease:

The agent must be present in every case of the disease. The agent must be isolated and cultured in vitro. The disease must be reproduced when a pure culture of the

agent is inoculated into a susceptible host. The agent must be recoverable from the experimentally-infected

host.

Fields of MicrobiologyBacteriology

Virology

Epidemiology

Immunology

Parasitology

Protozoology

Mycology

Virology

Recombinant DNA technology and genetic engineering

Biotechnology

Modern Microbiology