microbiology1st

• Microbes, also called microorganisms, are minute living things that individually are usually too small to be seen with the unaided eye
• Microbes include bacteria, fungi (yeasts and molds), protozoa, and microscopic algae
• Viruses are also considered microbes and are noncellular entities that are sometimes regarded as straddling the border between life and nonlife
• Majority of microorganisms help maintain the balance of living organisms and chemicals in the environment
• Marine and freshwater microorganisms form the basis of the food chain in oceans, lakes, and rivers
• Soil microbes help break down wastes and incorporate nitrogen gas from the air into organic compounds, recycling chemical elements between soil, water, life, and air
• Certain microbes play important roles in photosynthesis, a critical process for life on Earth
• Humans and many other animals depend on microbes in their intestines for digestion and synthesis of vitamins like B vitamins and vitamin K
• Microorganisms have many commercial applications and are used in the synthesis of chemical products like vitamins, organic acids, enzymes, alcohols, and drugs
• Microbes are used in the production of acetone, butanol, and vitamins like B2 (riboflavin) and B12 (cobalamin)
• Microbes are used in the food industry to produce vinegar, sauerkraut, pickles, soy sauce, cheese, yogurt, bread, and alcoholic beverages
• Enzymes from microbes can be manipulated to produce substances they normally do not synthesize, including cellulose, digestive aids, drain cleaner, and therapeutic substances like insulin
• Microbial enzymes may have contributed to the production of various products including clothing like jeans
• Practical knowledge of microbes is necessary for medicine and related health sciences
• Hospital workers must protect patients from common microbes that are normally harmless but pose a threat to the sick and injured
• Microorganisms are found almost everywhere and were unknown to scientists before the invention of the microscope
• Thousands of people died in devastating epidemics before the understanding of microbes, vaccines, and antibiotics
• Scientific nomenclature assigns each organism two names - the genus (always capitalized) and the specific epithet (species name, not capitalized), both underlined or italicized
• Scientific names can describe an organism, honor a researcher, or identify the habitat of a species
• Classification of microorganisms includes Bacteria, Archaea, Eukarya (Protists, Fungi, Plants, Animals)
• Bacteria are prokaryotic cells with various shapes like bacillus, coccus, and spiral, enclosed in cell walls mainly composed of peptidoglycan
• Bacteria reproduce by binary fission and use organic chemicals for nutrition, some can manufacture their own food by photosynthesis
• Archaea are prokaryotic cells found in extreme environments, divided into methanogens, extreme halophiles, and extreme thermophiles
• Fungi are eukaryotes with cells containing a distinct nucleus, cell walls composed primarily of chitin, and can be unicellular or multicellular
• Protozoa are unicellular eukaryotic microbes that move by pseudopods, flagella, or cilia, and can reproduce sexually or asexually
• Algae are photosynthetic eukaryotes with a wide variety of shapes, cell walls composed of cellulose, and produce oxygen and carbohydrates through photosynthesis
• Viruses are acellular entities containing a core made of DNA or RNA surrounded by a protein coat, reproduce only within host cells, and are considered parasites of other forms of life
• Multicellular animal parasites like helminths are eukaryotes and of medical importance
• Carl Woese devised a classification system based on cellular organization grouping organisms into Bacteria, Archaea, and Eukarya
• Microbiology dates back 200 years, with key developments like the discovery of cells by Robert Hooke and observation of microorganisms by Anton van Leeuwenhoek
• Spontaneous generation was a hypothesis that some forms of life could arise spontaneously from nonliving matter
• Francesco Redi's experiment in 1668 demonstrated that maggots did not arise spontaneously from decaying meat
• Redi's second experiment with a fine net covering the jar also showed that maggots appeared only when flies were allowed to lay their eggs on the meat
• John Needham's experiment in 1745 suggested that microorganisms developed spontaneously from heated nutrient fluids, but Lazzaro Spallanzani showed that microorganisms from the air likely contaminated the solutions
• Louis Pasteur's experiments in the mid-1800s demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but air itself does not create microbes
• Pasteur's experiments with short-necked flasks and S-shaped curves showed that air could pass into the flask without contaminating the broth, leading to the development of aseptic techniques
• Rudolf Virchow challenged spontaneous generation with the concept of biogenesis, claiming that living cells can only arise from preexisting living cells
• Louis Pasteur's work led to the establishment of microbiology as a science and the Golden Age of Microbiology from 1857 to 1914
• Joseph Lister applied the germ theory to medical procedures, using phenol to kill bacteria and reduce infections
• Robert Koch established Koch's postulates, linking specific microbes to specific diseases, and provided the first proof that bacteria cause disease