Chapter 1 Introduction

Ubiquitous – they are everywhere Air, water, Soil ( microbes are all around us) Normal flora – found in the gastrointestinal tract, genitourinary tract, respiratory tract, skin. Beneficial aspects and harmful aspects Normal flora protect us from diseases. They suppress the growth of pathogens. E. coli in the large intestine makes vitamin K – used for blood clotting.

Aquatic environments. Unicellular algae – bottom of the food chain. Unicellular algae > tiny fish > large fish > shark. Algae are autotrophs. They use CO 2 and water to make sugar. Soil microbes are involved in recycling chemical elements. Breakdown cellulose and release CO 2. Making food products (yogurt, cheese, bread). Yeast + flour > dough

Small ball of dough -----large ball of dough Therapeutic substances – genetic engineering is used to force E. coli to make human insulin. Bioremediation – microbes are used to clean up chemical pollutants (oil spills) in the environment. Insecticide – BT toxin is sprayed on plants. Sewage treatment – breakdown organic matter to produce methane.

Harmful aspects Tuberculosis, Lyme disease Spoilage of food products. Milk sour. Lactose --- acids. History of microbiology 1665 Robert Hooke – plant materials (leaves and stems). Little boxes – cells – 1723 Anton van Leeuwenhoek observe microbes under the microscope.

Rain water, scrapings from his teeth. Called the microbes animalcules. Spontaneous generation theory – life could arise from nonliving matter. Decaying meat give birth to maggots (larvae of flies)

Fine net No maggots

Needham 1745

Rudolph Virchow – theory of biogenesis. Life could arise only from pre-existing living cells Louis Pasteur disproved the spontaneous generation theory.

Pasteur’s experiment S shaped curve

Microbes are found in the air, in liquids and on solids. Foundation for the aseptic procedure used in the lab to prevent contamination

1857 – discovered fermentation. Yeast converted sugars in the grapes to alcohol and CO 2 in the absence of O – came up with pasteurization. Beverages such as milk are heated enough to kill microbes without destroying the flavor of the beverages.

Germ theory of disease A belief microbes could cause diseases. 1860s Joseph Lister treated surgical wounds with disinfectant Robert Koch proved the germ theory of disease. Animals such as cattle were dying of a disease.

Drew blood from the animals that had died of the disease. Isolated a rod-shaped bacterium (isolate #1) Grew bacterium in the lab and obtained a pure culture of the bacterium. Injected bacterium into healthy animals. They got sick and died. He isolated rod shaped bacterium from these animals (isolate #2)

Compared the 2 isolates and found that they were identical. Anthrax. Bacillus anthracis. The above steps are known as Koch’s postulates. They are used even today to determine the causative agent of a mysterious infectious disease Alexander Fleming discovered penicillin.

Naming organisms 1735 Carolus Linnaeus – binomial Genus and species Latin – describe the organism, honor a scientist. Staphylococcus aureus Escherichia coli

Diversity of Microorganisms Bacteria – prokaryotic Pre-nucleus – DNA is NOT surrounded by a membrane Unicellular Heterotroph – get energy from organic molecules. Cell walls - peptidoglycan

Fungi – yeasts and molds Eukaryotic – true nucleus Unicellular/multicellular Cell walls – chitin All are heterotrophs

Protozoa – eukaryotic Unicellular Heterotophs Algae – eukaryotic Unicellular/multicellular Autotrophs - photosynthesize

Viruses – acellular Either have DNA or RNA Obligate intracellular parasites Helminths – multicellular Worms Eggs are microscopic

Classification of organisms 1969 Robert whittaker 5 kingdom system Classification based on Cell type - prokaryotic/eukaryotic Cellular organization – unicellular/multicellular Nutritional requirements – photosynthetic/nonphotosynthetic

Classification of organisms Prokaryotae (monera) – prokaryotic organisms – bacteria Protista - protozoa Fungi – Yeasts and molds Plant – ferns, trees, flowering plants Animal – worms, insects, vertebrates

3 domains Ribosomal RNA sequence Archaea, Bacteria, Eukarya Bacteria – prokaryotic Normal flora, pathogens Peptidoglycan

Archaea Prokaryotic Unusual, extreme environments Salt lakes, dead sea Do not have peptidoglycan cell wall pseudomurein

Eukarya All the eukaryotic organisms Protozoa, fungi, plants and animals