MICROBIOLOGY AND IMMUNOLOGY (BIOL200/343), SUMMER, 2017 Lecture:2 MICROBIOLOGY AND IMMUNOLOGY (BIOL200/343), SUMMER, 2017 Dr.Q.M.I.Haq

Distribution of microorganisms Air Soil Water Animals Human body

Microbes Microbes are single celled organisms They are found practically EVERYWHERE on earth Also commonly known as bugs, germs and microbes Are invisible to the naked eye, you need a powerful microscope to see them. Are mostly useful, but some are harmful Have been around for 3.8 bn years. They have adapted to live in some of the harshest environments on earth.

Microbes exist in huge numbers In one single teaspoon of garden soil, there are over 100,000 microbes. In 1ltr of seawater, there are over 1bn microbes. On your hands there are more microbes than there are people in the world. There are so many microbes, that scientists have only named 0.5% of the. It is estimated that microbes comprise over 50% of the earth’s living matter. Less than 1% of all bacteria have been identified, cultured, and studied.

Microorganisms and Human Beings Beneficial activities: Most microbes are of benefit to human beings, some are necessary ( nitrogen, carbon cycles) Harmful activities: A portion of microbes cause diseases and are poisonous to human, and these are really that concern us in the study of Medical Microbiology, etc.

Microbes live among us Microbes are vital for life on Earth. In our food, cleaning up our waste, killing pests, making medicines, in the making of such things as leather, soy sauce, cheese and paper etc. Microbes in our mouths, in our bodies. Without microbes, life on this planet would be entirely different – they help in processing of food we eat, they generate oxygen, are part of the carbon and nitrogen cycles. They drive the chemistry of life, breaking things down into their parts so that life can being again (recycling).

Microbial Taxonomy/Microbial Classification Identifying, organizing, classifying and naming microorganisms according to specific criteria is known as Microbial Taxonomy. Formal system originated by Swedish scientist Carl Linnaeus.

In microbiology the binominal system of nomenclature is accepted, where each species has a generic and a specific name. The generic name is written with a capital letter, and the specific name – with a small letter. For example: Bacillus anthracis; Clostridium tetani etc. Both italicized or underlined Staphylococcus aureus (S. aureus) Bacillus subtilis (B. subtilis) Escherichia coli (E. coli)

Taxonomy Hierarchy

The three domains Attempt by Carl Woese to improve the accuracy of the classification system based on studies of rRNA. Eubacteria: ‘true’ bacteria, prokaryotes with no organized nucleus and no membrane-bound organelles. Archaea: archaebacteria or ‘ancient’ bacteria are also prokaryotes; most live in extreme environments Eukarya: single-celled and multicellular organisms which all have their DNA contained in a nucleus; plants, animals, protists, and fungi

Diversity of habitat of Archaebacteria Methanogens – use carbon dioxide to make methane; strict anaerobes; live in guts of termites and cattle, Siberian tundra etc., and in large intestines of dogs, pigs, and humans Thermophiles – live in sulfur hot springs where the pH is very acidic and temperatures are up to 90°C; some live in hydrothermal vents up to 105°C Halophiles – live in the Dead Sea, the Great Salt lake, and evaporated salt water ponds

Relationship of Microbes 12

Germ Theory of Disease Microorganisms cause disease Robert Koch (1876) proved that a particular microorganism cause a particular disease

In 1884, Robert Koch proposed a series of postulates in his treatise on Mycobacterium tuberculosis and tuberculosis.

Koch´s postulates are summarized as follows: The microorganism should be found in all cases of the disease. The microorganism should be grown in pure culture in vitro. When such a pure culture is inoculated into susceptible animal species, the typical disease must result. The microorganism must again be isolated from the lesions of such experimentally produced disease.

Koch´s postulates remain a mainstay of microbiology Koch´s postulates remain a mainstay of microbiology. However, since the late 19th century, many microorganisms that do not meet the criteria of the postulates have been shown to cause disease. For example, Treponema pallidum (syphilis) and Mycobacerium leprae (leprosy) cannot be grown in vitro.

Analysis of infection and disease through the application of principles such as Koch´s postulates leads to classification of bacteria as pathogenic or non-pathogenic. Modern-day microbial genetics has opened new frontiers to study pathogenic bacteria and differentiate them from non-pathogens.

The Importance of Microbiology Environment Medicine Food Industry Biotechnology Research

The Importance of Microbiology Humans & many other animals depend on the microbes in their intestines (microflora) for: The digestion & the synthesis of some vitamins that their bodies require some B vitamins = metabolism vitamin K = blood clotting Some microorganisms are used in commercial & industrial application # Industry: Chemicals --- organic acids ,enzymes & alcohol (ethanol, acetone, etc.) # Food: cheese, yogurt, bread, pickles & vinegar # Drugs --- antibiotics (penicillin)

Environment: microbes used to treat sewage and clean up pollution Bioremediation “Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site.” microbes cultured for their ability to digest oil and other petroleum derivatives.

Biotechnology: Recombinant products (e.g., human insulin, vaccines)