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 Cell wall Cell membrane Ribosome Peptidoglycan Pili DNA Flagella

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 3) Fomites: (inanimate objects) 1) Direct Contact: 2) Air:

Early microbiologists Louis Pasteur Concluded that microorganisms cannot spontaneously generate Showed world how heat kills microorganisms (pasteurization)

Microorganisms & You Food for heterotrophs typically are carbon-based 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