Chapter 23 “Bacteria”

1. Chapter 23 “Bacteria”

2. 23.1 Prokaryotes: Bacteria are… • Unicellular prokaryotes with no nucleus or membrane organelles • Ubiquitous • Most are helpful • Classified by their biochemistry, habitats, and methods of energy use and obtaining food • Heliobacter pylori • RNA, Eukarya and Archaea

3. Two Groups • Domain - Archaea • Kingdom – Archaebacteria • Lack peptidoglycan (protein carbohydrate) in cell wall • AKA Extremophiles - • Halophiles (love salt) • Methanogens (convert H2 and CO2 into methane gas) • Thermoacidophiles (love acidic, hot environments) • First organisms to colonize primitive earth

4. Domain – BacteriaKingdom – Eubacteria • Eu = True • 3 basic shapes • Bacilli – rod shaped. E. coli, Bacillus anthracis • Cocci – spherical shaped. Staphylococcus aureus, Streptococcus pyogenes • Spirilla – spiral shaped. Spirochette, Syphilis

5. Staining properties • Groups Eubacteria in two groups • Gram Staining • Gram Positive – Gram stain purple with crystal violet due to thick layer of peptidoglycan. Easier to kill with antibiotics • Gram Negative – Gram stain pink with safranin. Hard to kill with antibiotics due to thin layer of peptidoglycan Gram PositiveGram Negative

6. Important Bacteria: The good, the bad, the ugly • Nitrogen fixing bacteria Rhizobium fix N2 into the root nodules of legumes • Eschericheri coli and Salmonella sp. cause food poisoning • Gram positive Clostridium botulinum causes botulism • Gram positive Lactobacilli make yogurt • Bacillus anthracis caused anthrax • Actinomycetes make antibiotics such as streptomycin and tetracyclin • Cyanobacteria are photosynthetic • Gram negative Spirochetes cause Lyme disease, syphyllis • Gram negative Chlamydia cause an STI

7. More Bacterial Roles • Fermentation of milk products – sour cream, yogurt, buttermilk • Production of cheese • Fermentation to produce wine, sauerkraut, pickles • Mining and oil spill cleanup – Bioremediation • Biotechnology

8. 23.2 Biology of Prokaryotes: Basic Structure • Cell Wall • Plasma membrane • Ribosomes • Circular DNA • Pili (hairs) for adherence to host cells • Flagella (protein) for movement, capsule (made of polysaccharides) for attachment.

9. Endospores • Produced by Gram + (usually Bacillus and Clostridium) • A structure which encloses and protects the bacterial DNA • Dormant structure to survive adverse conditions (heat, cold, dryness, chemicals, radiation)

10. Methods of Respiration • Obligate aerobic bacteria must have oxygen; (Tuberculosis bacteria) • Obligate anaerobes die if oxygen is present; (Tetanus bacteria that causes lockjaw) • Facultative anaerobes do not need oxygen, but don’t die if oxygen is present; (E. coli) • Remember: anaerobes carry on fermentation, while aerobes carry on cellular respiration

11. Nutrition • Heterotrophic or autotrophic • Saprophytes – feed off dead, decaying material • Autotrophs – capable of making their own food; photoautotrophs photosynthesize, or chemoautotrophs oxidize inorganic compounds to release energy (ammonia, NH3) to form nitrite (NO2) • Heterotrophs – saprophytes (feed off decaying organic matter) or chemoheterotrophs, like us

12. Reproduction Asexually by binary fission • Conjugation - Sexual reproductive method . Two bacteria form a conjugation bridge or tube between them • Pili hold the bacteria together • DNA is transferred from one bacteria to the other 

13. Recombination • Transformation- bacteria pick up pieces of DNA from other dead bacterial cells • New bacterium is genetically different from original • Remember Griffith? Transduction – when a virus picks up a piece of DNA and transfers it to another bacterium

14. 24.3 Bacteria and Humans • Pathogens – disease causing agents (Pathology – science of studying diseases) • Can produce poisonous toxins (poisons) • Endotoxins are made of lipids and carbohydrates by Gram negative bacteria and released after the bacteria die (cause high fever, circulatory vessel damage) E. coli • Exotoxins are made of protein by Gram + bacteria;secreted into environment. Clostridium tetani

15. To fight them • Antibiotics interfere with cellular functions (Penicillin interferes with synthesis of the cell wall; tetracycline interferes with protein synthesis) • Some antibiotics are made by Actinomycetes bacteria or fungi (penicillin) • Broad-spectrum antibiotics affect a wide variety of organisms • Bacteria can mutate and become antibiotic resistant (often results from overuse of antibiotics) • MERSA

16. Antibacterial Agents • Disinfectants – inhibits growth on a non-living surface – bleach, ammonia • Antiseptics– inhibits growth on a living surface – alcohol, hydrogen peroxide • Sterilization – high heat or chemicals that kills bacteria

17. Diseases caused by bacteria • Anthrax • Botulism • Cholera • Cavities • Gonorrhea • Syphilis • Tetanus • Staph Infection (MRSA) • Food Poisoning • Lyme Disease • Diphtheria • Tuberculosis • Escherichia coli O157: H7 • Leprosy • Meningitis • Strep throat • Whooping cough (Pertussis) • Food poisoning *Results from decay of foods and production of toxins *33 million people/year get “stomach flu” *Seafood accounts for 20 – 25% of cases *33% of all raw poultry tests + for Staphylococcus *1 in every 200 eggs has Salmonella

18. 4 C’s of Food Safety Chill your foods Cook your food to the proper temperature Clean food and cooking surfaces Combat Cross Contamination