Week 1 Introduction to the Microbial World PDF

**Week 1 Introduction to the Microbial World** ============================================== The Science of Taxonomy - **Taxonomy:** classification, description, identification, and naming of living organisms - Carolus Linnaeus: Introduced [Linnaean taxonomy] in 1735 with \"Systema N...

**Week 1 Introduction to the Microbial World** ============================================== The Science of Taxonomy - **Taxonomy:** classification, description, identification, and naming of living organisms - Carolus Linnaeus: Introduced [Linnaean taxonomy] in 1735 with \"Systema Naturae\": Organized organisms into hierarchical levels: kingdom, class, order, family, genus, and species. - The most specific and basic taxonomic unit: species - At first, the original kingdom for this taxonomy was animal, plant and mineral A Human Microbiome Map - Points closer together are more similar; points further apart are more dissimilar. - Different parts of the body have distinct microbiomes. - Microbiomes vary based on lifestyle, diet, and environmental factors **Naming** Microbes and Bergey's Manuals - Binominal nomenclature: by Linnaeus: Two-word naming system **[(genus and species)]**. - **Example: *Escherichia coli* (genus Escherichia, species coli).** - Naming conventions: Genus capitalized, species not, both italicized - Names are derived from Latin, Greek or English **Types of microorganisms** - Varies in size, structure, habitat and metabolism - Most are unicellular **Prokaryotic vs Eukaryotic** - **Prokaryotic organisms:** - Single-celled - No nucleus - Single circular chromosome - Lack organelles - **Prokaryotic microorganisms:** - Unicellular organisms (bacteria and archaea) - **Bacteria:** - Found in almost every habitat on Earth - **Shapes**: Spherical (coccus), rod-shaped (bacillus), curved (vibrio, spirillum, spirochete). - Metabolism: Photosynthetic (e.g., cyanobacteria) and non-photosynthetic. - **Archaea** - Cell walls lack peptidoglycan; often composed of pseudopeptidoglycan. - Found in extreme environments; none are known human pathogens - **Eukaryotic organisms:** - Single or multicellular - Contains a nucleus - Evolved from prokaryotes - DNA consists of multiple linear chromosomes - Contains organelles - **Eukaryotic Microorganisms** - Uni or multicellular organisms (contain a nucleus) - **Protists**: - **Examples: Algae (photosynthetic, cellulose cell walls), Protozoa (diverse, motile, some pathogenic).** - **Fungi**: - **Yeasts (unicellular, used in food production, some pathogenic), Molds (multicellular, decomposers, some produce antibiotics).** **Viruses** - Acellular (no cell) - Consists of proteins and genetic material (RNA or DNA) - Can infect all types of cells Where pathogenic microorganisms can be found? - **Air**: Through respiratory droplets or aerosols from infected individuals. - **Water**: Contaminated drinking water or recreational water sources. - **Food**: Improperly cooked or contaminated food. - **Surfaces**: Contaminated objects or surfaces (fomites). - **Soil**: Soil contaminated with pathogens, particularly in agricultural settings. - **Animals**: Through direct contact with infected animals or their waste products. - **Human** **Contact**: Direct contact with infected individuals, including skin contact, bodily fluids, and through sexual contact - About 0.5 pound of us is from microorganisms like bacteria and viruses - Human body is made of 30 trillion human cells, and our microbiome is made of also 30 trillion bacteria, viruses and fungi **Symbiosis:** Meaning all organisms living together in close proximity - **Mutualism**: Both populations benefit. - ***Escherichia coli* in our large intestine produces vitamin K and gets nutrients from us** - **Amensalism**: One population is harmed while the other is unaffected. - ***Lucilia sericata* produces a protein that destroys *Staphylococcus aureus* on human skin; excessive hand washing can disrupt this and lead to S. aureus diseases** - **Commensalism**: One population benefits while the other is unaffected. - **Much of our microbiome are commensals (benefits from the host) e.g., *Staphylococcus epidermidis* of our skin** - **Neutralism**: Both populations are unaffected - **Hard to prove (likely there are some affects that we don't know about)** - **Parasitism**: One population benefits while the other is harmed. - **Disease-causing bacteria, viruses, fungi etc. e.g., *Salmonella spp, Vibrio cholerae, Helicobacter pylori*, *Hepatitis B*** **Dysbiosis** - Imbalance of microbial, particularly in the gut - Can lead to many diseases\' conditions - 3 categories: - Loss of beneficial organisms - Excessive growth of potentially harmful organisms - Loss of overall microbial diversity