Introduction to Microbiology PDF

Introduction to Microbiology ---------------------------- What is Microbiology? - From the Greek words "mikros" (small), "bios" (life), and "logia" or "logos" (study/ science) - The study of organisms that are so small they cannot be seen with the naked eye. - Microorganisms or mic...

Introduction to Microbiology ---------------------------- What is Microbiology? - From the Greek words "mikros" (small), "bios" (life), and "logia" or "logos" (study/ science) - The study of organisms that are so small they cannot be seen with the naked eye. - Microorganisms or microbes are categorized into: - Acellular Infectious Agents - Prions - Viruses - Cellular Microorganism - Prokaryotes - Archaea - Bacteria - Eukaryotes - Algae - Fungi - Protozoa Divisions of Microbiology: Bacteriology -- the study of bacteria Virology -- the study of viruses Mycology -- the study of fungi (mycoses) Parasitology- the study of protozoa and parasitic worms Phycology -- the study of algae Immunology -- the study of the immune system and the immune response Why Study Microbiology? - Normal Flora: The human body hosts around a thousand species of microorganisms, also known as normal or indigenous flora, which can cause disease mainly in individuals with compromised immune systems. - Biotechnology: Microorganisms play vital roles in various biotechnological applications such as food and beverage production, pharmaceuticals, and genetics. - Antimicrobial Agents: Many bacteria and fungi are sources of important antimicrobial agents. - Decomposition: Microbes act as saprophytes or decomposers, recycling nutrients in the ecosystem. - Awareness of Risks: Knowledge in microbiology provides insights into issues like the resurgence of diseases, biological warfare, and antibiotic resistance NOMENCLATURE - The body or system of names - Established by Carolus Linnaeus in 1735 - Latin was the language traditionally used by scholars. - Microorganisms are normally known by two names: Genus (plural = genera) Both are underlined OR *italicized* - Scientific names can, among other things, Describe an organism Honor a researcher Identify the habitat of the species Identify its use HISTORY OF MICROBIOLOGY ----------------------- Robert Hooke - An Englishman - Father of Cytology - Discovered the cell and described it as "little boxes" - The Cell Theory -- all living things are composed of cells. - Hooke's 1665 book, *Micrographia*, contained descriptions of plant cells Anton van Leeuwenhoek - Dutch merchant and an amateur scientist - Created the single lens microscope - The first to actually observe live microorganisms which he called *animalcules/ beasties* - Father of Microscopy - Simple Microscope - Father of Microbiology Louis Pasteur - Disproved the theory of Spontaneous Generation (abiogenesis) - Pasteur proved that only preexisting microbes could give rise to other microbes (biogenesis) - Developed the process of Pasteurization (food preservation) and Fermentation (the process in which a substance breaks down into a simpler substance) Ferdinand Julius Cohn - German biologist - Classification of bacteria into four groups based on shape Spherical = cocci short rods = bacilli threads = spirochetes spirals = spirillum - Gave some of the first insights into the incredible complexity and diversity of microbial life. Robert Koch - German physician - Father of Microbiological Techniques - Koch's postulates: a specific organism causes a specific disease. - Discovered: Edward Jenner - Father of Immunology - Discovered the first vaccine for smallpox (from the Latin word *vacca,* meaning cow) Joseph Lister - Father of Antiseptic Surgery - Joseph Lister found a way to prevent infection in wounds during and after surgery. - Introduced weak carbolic hand washes for surgical staff and carbolic acid baths for the instruments - Lister\'s Antisepsis System is the basis of modern infection control Paul Ehrlich - Father of Chemotherapy - Discovered Salvarsan for the treatment of syphilis (disease that was then endemic, incurable, and often deadly) - Chemotherapy: treatment of disease by using chemical substances - Salvarsan is also known as the "magic bullet" - Salvarsan became the most widely prescribed drug in the world, first blockbuster drug and remained the most effective drug for syphilis until penicillin became available Alexander Fleming - Discovered Penicillin from *Penicillium notatum* - Before its introduction there was no effective treatment for infections such as pneumonia, gonorrhea or rheumatic fever. Hospitals were full of people with blood poisoning contracted from a cut or a scratch - Introduction of penicillin in the 1940s, which began the era of antibiotics - Discovered on September 3, 1928 but was introduced as treatment by Howard Florey and Ernst Chain (Penicillin Discovery to Development) Ignaz Semmelweis - Hungarian physician - Father of Infection Control - First person to discover and propose the medical benefits of handwashing THE MICROBIAL WORLD ------------------- - All organisms are composed of cells, the basic fundamental unit of life. The cells of microorganisms are categorized into two -- prokaryotes and eukaryotes. - Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled. - Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle. - Viruses are acellular. They are neither prokaryotic nor eukaryotic Eubacteria - The bacteria of interest in medicine - Cell walls that are largely composed of a carbohydrate and protein complex called peptidoglycan. - Generally, reproduce by dividing into two equal cells called binary fission - Many bacteria can "swim" by using moving appendages called flagella Archaea - Have no medical importance - Often found in extreme environments, divided into three main groups: - methanogens produce methane as a waste product from respiration. - extreme halophiles live in extremely salty environments - extreme thermophiles live in hot sulfurous water - Not known to cause disease in humans Fungi - May be unicellular or multicellular - Large multicellular fungi such as mushroom, may somewhat look like plants, but they cannot carry out photosynthesis. - True fungi have cell walls composed primarily of a substance called chitin - Human fungal diseases (mycoses) are classified by the location on or in the body where the infection occurs. - Divided into two: Molds and Yeasts Protozoa - Unicellular eukaryotic microbes - Move by using extensions of their cytoplasm called pseudopods (false feet) - Other protozoa have long flagella or numerous shorter appendages for locomotion called cilia - Have a variety of shapes and live either as free entities or as parasites that absorb or ingest organic compounds from their environment. - Can reproduce asexually or sexually. Algae - Photosynthetic eukaryotes with a wide variety of shapes and both sexual and asexual reproductive forms ∙ The cell walls of many algae, are composed of a carbohydrate called cellulose - Algae are abundant in freshwater and salt water, in soil, and in association with plants - Do not produce significant disease in humans but are beneficial as sources of food, iodine, and other minerals. Helminths - Groups of worms that live as parasites - Eukaryotic organisms with complex body organization - They are parasitic in the sense that they receive nutrients by ingesting or absorbing digestive contents or ingesting or absorbing body fluids or tissues - They are divided into three main groups: - Tapeworms (cestodes) - Flukes (trematodes) - Roundworms (nematodes) Virus - Acellular, obligate intracellular parasites that is structurally very simple - Can reproduce only by using the cellular machinery of other organisms - A virus particle contains: - A core made up of only one type of nucleic acid, EITHER DNA or RNA. - The core is surrounded by a protein coat (capsid) - Sometimes, the coat is encased by an additional layer, a lipid membrane called an envelope. Prions - An infectious particle - A type of protein found in the brain that is responsible for a variety of extremely fatal neurodegenerative diseases of animals but can be transmitted to humans known as transmissible spongiform encephalitis (TSE) - To date, its cause or how it happens is still unknown. - Examples include Bovine Spongiform Encephalopathy (BSE) in cattle, Scrapie in sheep and goats and Creutzfeldt-Jakob Disease (CJD) in humans. CELLULAR STRUCTURES AND FUNCTIONS --------------------------------- Bacterial Shape -- arrangement Cocci -- spherical in nature - Diplococci - Tetrad - Sarcina - Streptococci - Staphylococci Bacilli -- rod-shaped in nature - Single - Diplobacilli - Streptobacilli - Coccobacilli Spiral -- curved or s-shaped in nature - Vibrio - Spirillum - Spirochetes Structures External to the Cell Wall - Glycocalyx - Evasion of phagocytosis (to get rid of microbes) - Aka Sugar Coat - The bacterial glycocalyx is a viscous (sticky), gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide, or both. - If glycocalyx is organized and is firmly attached to the cell wall, it is described as a capsule; if it is loosely attached, it is described as a slime layer - Flagella - Long filamentous appendages that propel bacteria. - Atrichous - Bacteria that lack flagella - Peritrichous - distributed over the entire cell; - Monotrichous - a single flagellum - Lophotrichous - a tuft of flagella coming from one pole - Amphitrichous - flagella at both poles of the cell - Axial Filaments - Aka Endoflagella - located inside the cell, found in spirochetes only - Have a structure similar to that of flagella. - The rotation of the filaments produces a movement of the outer sheath that propels the spirochetes in a spiral motion. - Pili (short)/Fimbriae (long) - Hair-like appendages that are shorter, straighter, and thinner than flagella - Used for attachment and transfer of DNA rather than for motility Cell Wall - Defines the shape of the bacterium - Protects bacteria from osmotic shock - If destroyed, the bacterium dies - The bacterial cell wall is composed of a macromolecular network called peptidoglycan (also known as *murein*) - The bacteria from the genus [Mycoplasma] do not have a cell wall. Hence, resistant to Gram Staining - Gram Positive Cell Wall - 40 layers thick, 90% peptidoglycan, 10% Teichoic acid - Teichoic acid - consist primarily of an alcohol (such as glycerol or ribitol) and phosphate. Teichoic acids may bind and regulate the movement of cations (positive ions) into and out of the cell. - They may also assume a role in cell growth, preventing extensive wall breakdown and possible cell lysis - There are two classes of teichoic acids: - Lipoteichoic acid- linked to the plasma membrane - Wall teichoic acid- linked to the peptidoglycan layer - Gram Negative Cell Wall - Very thin, 1 layer only, no teichoic acid but with outer cell envelope (makes the cell impermeable to antibacterial agents) - The outer cell envelope consists of: - lipopolysaccharide layer (LPS) which is toxic and antigenic (LIPID A - toxic portion which when released in the circulation may cause diarrhea, fever, dilation of blood vessels, shock, and blood clotting), - phospholipid layer - periplasmic space (contains antibiotic -inactivating enzyme) Structures Internal to the Cell Wall Plasma Membrane - serve as a selective barrier through which materials enter and exit the cell - selectively permeable because of phospholipids important to the breakdown of nutrients and the production of energy. - contains enzymes capable of catalyzing the chemical reactions that break down nutrients and produce ATP. Cytoplasm - 80% Water thick, aqueous, semitransparent, and elastic houses the nucleoid (containing DNA), particles called ribosomes, and reserve deposits called inclusions. Nucleoid - single long, continuous, and frequently circularly arranged thread of double-stranded DNA called the bacterial chromosome (which carries all the information required for the cell's structures and functions). Ribosome - Sites of protein synthesis - Composed of two subunits: 30S and 50S - Usually the target of many antibiotics Plasmids - extrachromosomal genetic elements that are not connected to the main bacterial chromosome, but can replicate independently of chromosomal DNA. - Plasmids may carry genes for such activities as antibiotic resistance, tolerance to toxic metals, the production of toxins, and the synthesis of enzymes. - Used for gene manipulation in biotechnology - Inclusions - Aka Reserve deposits - Cells may accumulate certain nutrients when they are plentiful and use them when the environment is deficient. Endospores - aka resting cells - produced by bacteria (genus Bacillus and Clostridium) when they are under hostile environment - composed of dipicolinic acid which is resistant to heat, drying, chemical agents and radiation - the process of spore formation is called sporulation which occurs when environment is not favorable to the bacterium. Germination is the process called when bacterium returns to its vegetative state Application and Real-World Relevance - The study of microorganisms has significant implications in various fields: Medicine: Understanding pathogenic bacteria guides antibiotic treatment and vaccine development. Biotechnology: Microorganisms are engineered for various applications, including gene therapy and bioremediation. Environmental Science: Microbes contribute to nutrient cycling, soil health, and biogeochemical processes