Microbiology Concepts & History PDF

Used until today to prove the causative agent of an infection disease for e.g. Covid-19 Figure 1.29 A hand-colored photograph taken by Walther Hesse of colonies formed on agar. The colonies include those of molds and bacteria obtained during Hesse’s studies of th...

Used until today to prove the causative agent of an infection disease for e.g. Covid-19 Figure 1.29 A hand-colored photograph taken by Walther Hesse of colonies formed on agar. The colonies include those of molds and bacteria obtained during Hesse’s studies of the microbial content of air in Berlin, Germany, in 1882. From Hesse, W. 1884. “Ueber quantitative Bestimmung der in der Luft enthaltenen Mikroorganismen.” Mittheilungen aus dem Kaiserlichen Gesundheitsamte. 2: 182–207. Figure 1.30  Microbial diversity: focuses on nonmedical aspects of microbiology in soil and water Enrichment culture Martinus Beijerinck (1851–1931) Developed enrichment culture technique Microbes can be isolated from natural samples in a highly selective fashion by manipulating nutrient and incubation conditions: example: nitrogen-fixing rhizobia (Figure 1.9) Figure 1.9  Discovery of chemolithotrophy Sergei Winogradsky (1856–1953) and the concept of chemolithotrophy demonstrated that specific bacteria are linked to specific biogeochemical transformations (e.g., N and S cycles) (see Figure 1.32) proposed concept of chemolithotrophy: oxidation of inorganic compounds to yield energy demonstrated chemolithotrophs use carbon from CO2 (autotrophy) first to demonstrate nitrogen fixation (Clostridium pasteurianum) and nitrification  The start of modern antibiotics Penicillium in culture Antibiotic susceptibility test Sir Alexander Fleming Fleming discovered, by “accident”, antibiotic substance benzylpenicillin (Penicillin G) from the mold (fungus) Penicillium notatum in 1928. β-Lactam ring β-Lactam antibiotics inhibit the formation Wikipedia of peptidoglycan cross-links in the bacterial cell wall.  Microorganisms and the biosphere History of Life on Earth Earth is 4.6 billion years old. First cells appeared between 3.8 and 4.3 billion years ago. The atmosphere was anoxic (no O2) until ~2.6 billion years ago. only anaerobic metabolisms first anoxygenic phototrophs ~3.6 billion years ago plants and animals ~0.5 billion years ago LUCA : the last universal common ancestor Figure 1.5  Microbial ecology Notable umbers: – ~2 x 1030 microbial cells on Earth – in humans, 1–10 microbial cells per human cell Ecosystem refers to all living organisms plus physical and chemical constituents of their environment. Metabolic activities can change habitats and affect other organisms. Structures and colors formed by microbes in the environment Halobacteria http://www.biochem.mpg.de/522218/Org_Hasal http://halo.umbc.edu/haloed/motility Lake Hillier of Australia’s Recherche Archipelago; Pink color possibly caused pink bacteria halobacteria living in high salinity lake water. https://www.tumblr.com/search/halobacteria Extremophiles live in habitats too harsh for other life forms. examples: hot springs, glaciers, high salt, high acidity/alkalinity, high pressure (Table 1.1) Table 1.1 The Impact of Microorganisms on Human Society Microorganisms can be both beneficial and harmful to humans. agents of disease food and agriculture valuable human products, energy generation, environmental clean-up For plant: nitrogen-fixing bacteria For animal: cellulose-degrading microbes in rumen