Microorganisms and Their Roles PDF

Microorganisms as disease agents Bacterial, fungal, parasitic, and viral pathogens Figure 1.8  Most microorganisms are with us and beneficial Figure 1.10 Gut microbiome: digests complex...

Microorganisms as disease agents Bacterial, fungal, parasitic, and viral pathogens Figure 1.8  Most microorganisms are with us and beneficial Figure 1.10 Gut microbiome: digests complex carbohydrates in humans: synthesize vitamins and other nutrients Commensal microorganisms and human Commensal population of microbes plays a critical role in human survival by participating in the metabolism of food products, provides essential growth factors, protects against infections with highly virulent microorganisms, and stimulates the immune response.  Microorganisms and food negative impacts can cause food spoilage and foodborne disease harvest, storage, safety, prevention of spoilage influenced by microbes positive impacts improving food safety, preservation dairy products (e.g., cheeses, yogurt, buttermilk) other food products (e.g., sauerkraut, kimchi, pickles, chocolate, coffee, leavened breads, beer) Figure 1.11  Microorganisms and industry Biofilms: growth on submerged surfaces (e.g., pipes, storage tanks, implanted medical devices) - Bad Industrial microbiology: massive growth of naturally-occurring microbes to make low-cost products (e.g., antibiotics, enzymes, some chemicals) – good Biotechnology and synthetic biology: genetically engineered microbes making high-value products in small amounts – great and the future!  Production of biofuels examples: methane, ethanol (Figure 1.12) Wastewater treatment Bioremediation: cleaning up pollutants Figure 1.12 Structure and activities of microbial cells The cell: A living compartment that interacts with the environment and other cells Elements of microbial structure All cells have the following in common (Figure 1.3): cytoplasmic (cell) membrane: barrier that separates the inside of the cell from the outside environment cytoplasm: aqueous mixture of macromolecules, small organics, ions, and ribosomes inside cell ribosomes: protein-synthesizing structures cell wall: present in some microbes; confers structural strength  Prokaryotic versus eukaryotic cells Prokaryotes (Figure 1.3a) Bacteria and Archaea no membrane-enclosed organelles (membrane-enclosed structures), no nucleus generally single circular chromosome that aggregates to form the nucleoid region (Figure 1.3a) may also have plasmids (extrachromosomal DNA) that confer special properties (e.g., antibiotic resistance) small, compact (0.5–10 million base pairs) Eukaryotes (Figure 1.3b) plants, animals, algae, protozoa, fungi contain organelles DNA enclosed in a membrane-bound nucleus Linear and much larger/more DNA (up to billions of base pairs) Figure 1.3  Activities of microbial ells In nature, cells typically live in microbial communities. metabolism: chemical transformation of nutrients enzymes: protein catalysts transcription: DNA information converted to RNA translation: RNA used by ribosome protein Motility: Many cells move through self- propulsion. Differentiation: Some microbes modify structures to form specialized cell. Intercellular communication: Some microbes respond to other microbes. Evolution: Genetic changes transfer to offspring. Figure 1.4