bacteria chapter 24. two kingdoms of prokaryotes
TRANSCRIPT
BacteriaChapter 24
Two Kingdoms ofProkaryotes
Comparing EubacteriaWith Archaebacteria
Three Bacterial Cell Shapes
Gram Staining
Tour of a Bacterium
Bacterial Diseases and Modes of Transmission
Gram-positive bacteria (Gram +) • Thick layer of peptidoglycan
(protein-sugar) complex in cell walls & single layer of lipids
• Stain purple
• Lactobacilli are used to make yogurt, buttermilk ….
• Actinomycetes make antibiotics like tetracycline & streptomycin
Gram-negative bacteria (Gram -)• Cell walls have a thin layer of
peptidoglycan & an extra layer of lipids on the outside
• Stain pink or reddish • Lipid layer prevents the purple stain &
antibiotics from entering (antibiotic resistant)
• Some are photosynthetic but make sulfur, not oxygen
Mixture of gram positive and gram negative bacteria, G+ purplish, G-
Pinkish
Bacteria
Kingdom Archaebacteria• Found in harsh environments (undersea
volcanic vents, acidic hot springs, salty water)
• Cell walls without peptidoglycan • Subdivided into 3 groups based on their
habitat --- methanogens, thermoacidophiles, & extreme halophiles
Methanogens• Live in anaerobic environments (no oxygen) • Obtain energy by changing H2 and CO2 gas into
methane gas • Found in swamps, marshes, sewage treatment
plants, digestive tracts of animals • Break down cellulose for herbivores (cows) • Produce marsh gas or intestinal gas (methane)
Extreme Halophiles• Live in very salty
water.• Found in the dead sea,
great salt lake, etc.• Use salt to help
generate ATP (energy).
Thermoacidophiles (Thermophiles)
• Live in extremely hot (1100C) and acidic (ph 2) water
• Found in hot springs in Yellowstone national park, in volcanic vents on land, & in cracks on the ocean floor that leak scalding acidic water
Kingdom Eubacteria (true bacteria)• Most bacteria in this kingdom • Come in 3 basic shapes --- cocci (spheres), bacilli
(rod shaped), spirilla (corkscrew shape)
• Bacteria can occur in pairs ( diplo- bacilli or cocci)
• Bacteria occurring in chains are called strepto- bacilli or cocci
• Bacteria in grapelike clusters are called staphylococci
• Most are heterotrophic (can’t make their own food)
• Can be aerobic (require oxygen) or anaerobic (don’t need oxygen)
• Subdivided into 4 phyla --- Cyanobacteria (blue-green bacteria), spirochetes, gram-positive, & Proteobacteria
• Can be identified by gram staining (gram positive or gram negative)
• Disease-causing gram + bacteria produce poisons called toxins
• Clostridium causes tetanus or lockjaw • Streptococcus cause infections such as
“strep” throat • Staphylococci cause “staph” infections • Also cause toxic shock, bacterial
pneumonia, botulism (food poisoning), & scarlet fever
• Can be treated with penicillin (antibiotics) & sulfa drugs
Nutrient pollution often causes explosive algal growth which depletes waters of oxygen when the algae die. Toxic and foul smelling compounds may also be produced through this process. Nutrient pollution is the single largest pollution problem effecting coastal waters of the United States (Howarth et al., 2000). Most excess nutrients come from discharges of sewage treatment plants and septic tanks, storm-water runoff from overfertilized lawns, golf courses and agricultural fields. Over 60 percent of the coastal rivers and bays in the United States are moderately to severely affected by nutrient pollution (Howarth et al., 2000). (Photo: Weeks Bay NERRS site)