Microorganisms, Tiny Titans of the Earth PDF

Microorganisms, Tiny Titans of the Earth Microorganisms (microbes) are life forms too small to be seen by the human eye diverse in form/function inhabit every environment that supports life many single-celled, some form complex structures, some multicellular live in microbial...

Microorganisms, Tiny Titans of the Earth Microorganisms (microbes) are life forms too small to be seen by the human eye diverse in form/function inhabit every environment that supports life many single-celled, some form complex structures, some multicellular live in microbial communities (Figure 1.1) Phase-contrast Fluorescent microscopy microscopy Scanning electron micrograph Figure 1.1  Microorganisms, Tiny Titans of the Earth Oldest form of life Major fraction of Earth’s biomass Surround plants and animals Inside the bodies and tissues Affect human life (infectious diseases, food and water, soils, animal health, fuel)  Tools for studying microorganisms Grow and visualization: microscopy culture: cells grown in/on nutrient medium medium: liquid/solid mixture containing all required nutrients for example, bacteria can grow to form a visible colony on a culture plate (Figure 1.2) Molecular, genomic and immunological techniques PCR sequencing antibody-based tests …  Macroscale: Microscale: A single colony can contain A bacterial cell in this colony is more than 10 million (107) about 10 µM in length individual cells. Figure 1.2  Historical perspective of microbiology Infusoria under microscope Antonie van Leeuwenhoek Otto Friedrich Müller 1632-1723 http://ikanrainbowfish.blogspot. Danish naturalist Invented microscope. hk/2013/07/kultur-infusoria.html 1730 -1784 Organized bacteria into genera and species according to the classification methods Wikipedia of Carolus Linnaeus.  “Germ theory” – diseases are caused by microbes Wikipedia Friedrich Henle Louis Pasteur Robert Koch In 1840, the German pathologist Friedrich Henle proposed criteria for proving that microorganisms were responsible for causing human disease (the “germ theory” of disease). Robert Koch and Louis Pasteur confirmed this theory in the 1870s and 1880s with a series of elegant experiments proving that microorganisms were responsible for causing anthrax, rabies, plague, cholera, and tuberculosis.  Pasteur disproved spontaneous generation theory Louis Pasteur: chemist and microscopist discovered that living organisms discriminate between optical isomers (Figure 1.25) discovered that alcoholic fermentation was a biologically (not just chemically) mediated process Using the swan-necked Pasteur flask, he disproved theory of spontaneous generation (Figure 1.26): Life arose spontaneously from nonliving material. – led to sterilization methods and food preservation developed vaccines for anthrax, fowl cholera, and rabies Swan-necked Pasteur flask Figure 1.26 Koch, Infectious Disease, and Pure Cultures Robert Koch (1843–1910): physician and microbiologist (Figure 1.28) experimentally demonstrated the link between microbes and infectious diseases (germ theory of infectious disease) identified causative agents of anthrax, tuberculosis, and cholera Koch's postulates (Figure 1.29) developed solid media for obtaining pure cultures of microbes (Figure 1.30) observed that masses of cells (called colonies) have different shapes, colors, and sizes awarded Nobel Prize for Physiology and Medicine in 1905