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Bacteria Chapter 19-1 Microscopic organisms • Viruses = not living, but studied as micro• Bacteria = divided into 2 kingdoms; most are helpful, harmful tracked by CDC & WHO • Protists = most diverse; show fungal, plant or animal characteristics • Fungus = decomposers; most are helpful, some are disease-causing Prokaryote characteristics Single-cell organisms Anucleated (no nucleus) Small (1-5 m) Lacks organelles Variety of shapes Variety of growth patterns Two kingdoms: Eubacteria and Archaebacteria Bacterial characteristics: • Prokaryotic (no nuclear membrane) – Ribosomes only – Pili = for attachment – Capsule = outermost layer for extra protection • • • • Unicellular (some colonial) Varied metabolism & nutritional types Often flagellated May contain endospores… to survive harsh conditions • Binary fission to reproduce Archaebacteria • Extremophiles: organisms that prefer extreme environments • Ex: salt marshes, deep sea ocean vents, swamps, etc. aerobic halophil Archaebacteria • Lack the peptidoglycan of Eubacteria • Have different membrane lipids • DNA sequences are more like those of eukaryotes Chemosynthetic bacteria in deep sea vents Photosynthetic Cyanobacteria in fresh-water ponds or streams Eubacteria cell structure Peptidoglycan Cell Cell Ribosome wall membrane Flagella DNA Pili See page 465 Practice Bacterial shapes • • • • Bacillus = rod-shaped (ex: Lactobacillus) Coccus = sphere (ex: Streptococcus) Spirillum = coiled (ex: Spirochete) Strepto(chains) • Staphylo(clusters) (like grapes) • Diplo- (pairs) Bacterial morphology Coccus Bacillus Spirillum Blue = causes Lyme disease Black = causes syphilis A Bacilli with and without flagella B Streptococci C Staphylococci D Diplococci E Spirochete F Club rod G Filamentous H Streptobacilli Movement • Depending upon how the cells is flagellated, movements such as gliding or tumbling may occur. flagellated E. coli Gram stain • a technique that determines the differences in the composition of bacterial cell walls (thick or thin) which helps to determine which antibiotics to use. Gram-positive bacteria thick peptidoglycan cell walls. Gram-negative bacteria thinner cell walls with a outer lipid layer. Gram negative Gram positive How bacteria obtain nutrition • Heterotrophs: consume carbon matter to make ATP – Chemoheterotroph: consumes only – Photoheterotroph: consumes and photosynthesizes Gram-negative, facultative anaerobic How bacteria obtain nutrition • Autotrophs: produces carbon matter to make ATP • Photoautotroph: produces with light energy (photosynthesis) • Chemoautotroph: produces carbon matter without light source Chemoautotroph: Purple sulfur bacteria Nutritional diversity (Recap) • Autotrophs: (producers) – Photosynthetic = Cyanobacteria – Chemosynthetic = bacteria in deep ocean vents use sulfur instead of light for energy • Heterotrophs: (consumers) – Saprobes = decomposers feed on dead organic matter (nitrogen-fixing bacteria) – Parasitic = feed on living host (pathogenic) Oxygen requirements • Obligate aerobe: requires constant oxygen supply in environment • Facultative aerobes: prefers oxygen, but not necessary • Facultative anaerobe: can survive with or without oxygen • Obligate anaerobe: requires constant lack of oxygen in environment Binary fission • asexual method of reproduction • parent cell splits into two daughter cells • Daughter cells are identical to parent cell Binary fission • Cell Replication • (cloning) for prokaryotic cell • Much simpler than mitosis (like cytokinesis without the 4 other stages) Conjugation • Genetic material exchange • Increases genetic variation within bacterial population Spore formation • In unfavorable growth conditions, structures (endospores) form to protect the bacterium. • Thick wall encloses the DNA and a small amount of cytoplasm. • The rest of the cell dies off. • The spore can survive in tough conditions for years. • Ex: Bacillus anthracis (anthrax) causes black necrotic lesions, sudden massive chest oedema followed by cardiovascular shock then death Endospore formation Methods of Microbe Transmission 1) Direct Contact: 2) Air: 3) Fomites: (inanimate objects) Early microbiologists • Louis Pasteur • Concluded that microorganisms cannot spontaneously generate • Showed world how heat kills microorganisms (pasteurization) Microorganisms & You • Food for heterotrophs typically are carbonbased macromolecules: • Carbohydrates, lipids, & proteins • Bacteria & fungus are responsible for food spoilage because many are saprobes Helpful bacteria • Decomposers • Nitrogen fixers: Rhizobium • Symbiosis with humans in large intestines • Food production Rhizobium Food & Microorganisms: Making cheese • Bacteria placed in an anaerobic environment, and the milk breaks down to form cheese • Milk (sugar source) + little oxygen → lactic acid + protein solids + curds “Little Miss Muffet, sat on her tuffet, eating her… cottage cheese” Yogurt: • Yogurt is produced by a mixed culture of 2 types of bacteria. Imbedded in particles of the protein casein, you will see chains of cocci or diplococci (Streptococcus thermophilus) and big rod-shaped bacilli (either Lactobacillus acidophilus or L. bulgaricus). Buttermilk: • Buttermilk is the fermentation of milk by a culture of lactctic-acid producing Streptococcus lactis plus Leuconostoc citrovorum which converts lactic acid to aldehydes and ketones which gives buttermilk its flavor and aroma. Making cured meats • Some bacteria are able to ferment meat products • The final products are sausages, bologna, salami, country cured hams, etc Making pickled vegetables • Sauerkraut is a product of lactic acid fermentation of Lactobacillus genus bacteria. • Bacteria ferments the cabbage, but salt is added to prevent other bacteria from spoiling the product. Some cured food products • Cured animal products: • Beef • Corned beef • Bresaola • Tapa • Pork • Ham • Prosciutto • Jambon de Bayonne • Jamón serrano • Jinhua ham • Coppa • Lomo • Capicola • Lardon Bacon and Pancetta Elenski but Sausage Salami Pepperoni Chorizo Linguiça Fish Anchovy Salt cod Lox (salmon) Pickled herring Cured vegetable products: Tofu Sauerkraut Kimchi Pickled cucumbers Olive (fruit) Nitrogen cycle includes nitrogen fixation How else are bacteria helpful? • Nitrogen-fixation • decomposing bacteria convert atmospheric N2 for use by autotrophs • Symbiotic bacteria allow a host to live a different lifestyle than would normally be possible • Cyanobacteria (& unicellular algae) produce most of the world’s oxygen by photosynthesis Microorganisms & your health Antibiotics that kill pathogenic microorganisms are made from microorganisms