Lecture 01 General Microbiology PDF

Department of Mathematics & Natural Sciences MIC101 GENERAL MICROBIOLOGY Lecture 01 What are microbes? The word Microorganism came from the Greek word, mikrós, "small" and organismós, "organism" Microorganisms or microbes are microscopic organisms that exist as...

Department of Mathematics & Natural Sciences MIC101 GENERAL MICROBIOLOGY Lecture 01 What are microbes? The word Microorganism came from the Greek word, mikrós, "small" and organismós, "organism" Microorganisms or microbes are microscopic organisms that exist as ? unicellular, multicellular, or cell clusters. Microorganisms are widespread in nature and are beneficial to life, but some can cause serious harm.  Microbiota means the What is collection of microorganisms Microbiota/ of a particular site, habitat, or geological period. Microbiome Microbiome means the Important note: The terms Microbiota and Microbiome are ? combined genetic material often used interchangeably. (i.e. DNA and RNA) of the microorganisms in a particular environment. Role of Microbiome Humans and many other animals depend on these microbes to maintain good health. Bacteria in our intestines, including E. coli, aid digestion and even synthesize some vitamins that our bodies require, including B vitamins for metabolism and vitamin K for blood clotting. They also prevent growth of pathogenic species that might otherwise take up residence. Many factors influence where and whether a microbe can indefinitely colonize the body as benign normal microbiota or transient microbiota. Microbes can colonize only those body sites that can supply the appropriate nutrients. Temperature, pH, and the presence or absence of chemical compounds are some factors that influence what types of microbes can flourish. What is microbiology? ‘Microbiology’ should be an easy word to define: the science (logos) of small (micro) life (bios). Microbiology is the study of microorganisms, or microbes, a diverse group of generally minute simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses. It usually includes microbes less than about one millimetre (1 mm) in diameter.  Microbiology Morphology Ecology Metabolism Genetics Pathology Application Engineering  Seeing the Unseen The first instrument used in microbiology was a microscope; an optical instrument which magnifies the dimension of an object for visualization. Six major groups of microorganisms Bacteria (mostly unicellular micro-organisms without organized nucleus that usually get its energy from oxidizing organic compounds). Archaea (mostly unicellular micro-organisms without organized nucleus that survive mostly in extreme heat, acidity, alkalinity or extreme concentration of particular chemicals) Protozoa (unicellular microbes with nucleus but without cell walls that depend on organic materials for nutrition) Fungus (uni-cellular or multi-cellular microbes with organized nucleus and rigid cell walls that are totally dependent on organic nutrients for survival) Algae (microbes with nucleus that can make its own food from sunlight and inorganic elements) Virus (non-cellular genetic elements carrying DNA or RNA that can replicate only inside living cells)  Bacteriology for bacteria Branches of Virology for virus Microbiology Mycology for fungus Phycology for algae Parasitology for protozoa Study of extremophiles for Archaea Classification Systems in the Prokaryotes Bacterial Nomenclature System -The system of binomial nomenclature (naming) for organisms in use today was established in 1735 by Carolus Linnaeus. -Scientific names are Latinized because Latin was the language traditionally used by scholars. -Scientific nomenclature assigns each organism two names-the genus (plural: genera) is the first name and is always capitalized; the specific epithet (species name) follows and is not capitalized. -The organism is referred to by both the genus and the specific epithet, and both names are underlined or italicized. By custom, after a scientific name has been mentioned once, it can be abbreviated with the initial of the genus followed by the specific epithet Bacterial Scientific names can, (i) describe an organism, (ii) honor a researcher, or (iii) identify the Nomenclatur habitat of a species. -For example, consider Staphylococcus aureus, e Systems a bacterium commonly found on human skin. -Staphylo- describes the clustered arrangement of the cells; coccus indicates that they are shaped like spheres. -The specific epithet, aureus, is Latin for golden, the color of many colonies of this bacterium. -The genus of the bacterium Escherichia coli is named for a scientist, Theodor Escherich, whereas its specific epithet, coli, reminds us that E. coli live in the colon, or large intestine. Classification of Microorganisms In 1978, Carl Richard Woese, a professor of Microbiology, devised a system of classification based on cellular organization of organisms. It groups all organisms in three domains, namely, Bacteria, Archaea, and Eukarya. 1. Bacteria (prokaryotic; cell walls contain a protein-carbohydrate complex called peptidoglycan) 2. Archaea (prokaryotic; cell walls, if present, lack peptidoglycan) 3. Eukarya (eukaryotic), which includes the following: (i) Protists (slime molds, protozoa, and algae), (ii) Fungi (unicellular yeasts, multicellular molds, and mushrooms), (iii) Plants (includes mosses, ferns, conifers, and flowering plants), and (iv) Animals (includes sponges, worms, insects, and vertebrates). Task: Find out the six kingdoms proposed by Carl Woese Ribosomes are structures in the cytoplasm where proteins are made. All cells contain ribosomes, both prokaryotes and eukaryotes. The discovery of three cell types was based on the observations that ribosomes are not the same in all cells. Comparing the sequences of nucleotides in ribosomal RNA (rRNA) of organisms, phylogenetic trees are constructed. Looking back: The history of microbiology Theory of Spontaneous Generation Till the second half the nineteenth century, scientists and philosophers believed that some forms of life could arise spontaneously from nonliving matter, they called the hypothetical process Spontanous Generation. Even at the beginning of 1800, people commonly believed that toads, snakes and mice could be born of moist soil, that flies could emerge from manure; and that maggots, the larvae of flies could arise from decaying corpses. The debate over Spontaneous Generation  Redi’s Experiment Redi filled two jars with decaying meat. The first was left unsealed, allowing flies to lay eggs on the meat, which developed into larvae. The second jar was sealed, and because the flies could not get inside, no maggots appeared. 1. Evidence against Spontaneous generation 2. But opponents said- Maggots needed fresh air. Fresh air needed for spontaneous generation So Redi set up a second experiment, in which he covered a jar with a fine net instead of sealing it. No larvae appeared in the gauze-covered jar, even though air was present. Task: Read more from the book “Microbiology _ an introduction by Gerard J Tortora (13 Ed)”, Page: 33-34 John Needham fought back with an experiment in support of spontaneous generation theory in 1745, John Needham found that even after he heated chicken broth prior to pouring them into covered flasks, the cooled solutions were soon teeming with microorganisms. Needham claimed that microbes developed spontaneously from the fluids. Boiled chicken broth to kill all Still, broth became Claimed, microbes microorganisms, cloudy with developed covered flask, cooled microorganisms spontaneously the broth Task: Can you point out what might have gone wrong with Needham’s experiment? Lazzaro Spallanzani’s answer to Needham’s experiment 1. suggested, air exposure might be the reason of growth of microorganisms 2. So Spallanzani covered the flask, then boiled chicken broth perfectly. 3. No microbial growth Interestingly, when Needham was asked about Spallanzani’s experiment, he said- vital force (oxygen) was destroyed, which is why, microorganism couldn’t grow.  Pasteur’s Swan Neck Flask Experiment to finally disprove spontaneous generation theory Task: What was the purpose of S-shaped tube?  Biogenesis is the theory that living things come only from other pre-existing living things Abiogenesis is the study of how biological life arises from non-living matter through natural processes Note: Abiogenesis theory and Spontaneous Generation theory are grossly similar, however, there are fundamental differences as well. Abiogenesis hypothesizes that primitive lifeforms such as self-replicating RNA & Protein molecules originated from non-living matter. Whereas, Spontaneous Generation assumed that complex life form could emerge from non-living matter. To date, Spontaneous Generation is disproved and rejected, but Abiogenesis is neither proved or disproved. Thank you