The Diversity of Prokaryotic Organisms

1. The Diversity of Prokaryotic Organisms Chapter 11

2. Domains Bacteria and Archaea One circular chromosome not in a membrane 70S ribosomes No membrane-bound organelles Binary fission rRNA provides evidence of phylogenic differences between the 2 Domains

3. Domain Bacteria • Proteobacteria • Includes most of the gram-negative bacteria • Phylogeny based on rRNA studies • Common photosynthetic ancestor • few are still photosynthetic • Mythical Greek god, Proteus • Largest taxonomic group of bacteria • Classes designated by Greek letters

4. The  (alpha) Proteobacteria • Some grow at low nutrient levels • Some have unusual morphology • Many are agriculturally important • several medically important genra

5. The  (alpha) Proteobacteria • Human pathogens: • Bartonella - bacillus • Cat-scratch disease

6. Obligate intracellular parasite: • Rickettsia – bacillus or coccobacilli • Arthropod-borne cause spotted fevers • R. typhi - Endemic murine typhus (fleas) • R. rickettsii - Rocky Mountain Spotted Fever (ticks)

7. Have prosthecae: • Caulobacter • Stalked bacteria found in low nutrient aquatic environment • Hyphomicrobium • Budding bacteria found in low nutrient environment

8. Pelagibacter • Very small with tiny genome • P. ubique is abundant marine microbe

9. Nitrogen-fixing bacteria: • Azospirillum • Grows in association with tropical grasses and sugar cane • Rhizobia • Rhizobium, Bradyrhizobium • Infects roots of legumes forming root nodules

10. Nitrifying bacteria : • Chemoautotrophs • Oxidize nitrogen • Nitrosomonas NH4+ NO2– (ammonium to nitrite) • Nitrobacter NO2– NO3– (nitrite to nitrate)

11. Plant pathogen: • Agrobacterium • Inserts plasmid into plant cells, inducing tumors • Crown gall

12. Produce acetic acid from ethyl alcohol: • Acetobacter • Gluconobacter

13. Wolbachia • Most common infectious bacteria • Endosymbionts of insects and other animals

14. The  (beta) Proteobacteria • Utilize nutrients diffusing from areas of decomposition of organic matter • hydrogen gas, ammonia, and methane

15. Thiobacillus • Chemoautotroph, oxidizes sulfur: H2S  SO42– • Sphaerotilus • - hollow sheath • - polar flagella • - problem in sewage

16. Spirillum • Large, aerobic freshwater bacterium

17. Neisseria • N. meningitidis • Meningococcal meningitis • N. gonorrhoeae

18. Bordetella • Aerobic, rods or coccobacillus • B. pertussis - whooping cough

19. The  (gamma) Proteobacteria • Largest subgroup • Great variety of physiological types • Includes the enterics

20. Beggiatoa • Chemoautotroph, oxidize H2S to S0 • Gliding motility • Beggiatoa alba is only species • Azotobacter and Azomonas • Nitrogen fixing, free-living soil bacteria • Large ovoid cell with heavy capsule

21. Francisella • Pleomorphic • Francisella tularensis – tularemia (rabbit fever) • Resistant to many antibiotics

22. Pseudomonas • Aerobic rods; Polar flagella • Extra-cellular and/or florescent pigments • Opportunistic pathogen • Metabolize wide variety of substrates • Resistant to many anti-microbials • Denitrification

23. Legionella • Found in streams, warm-water pipes, cooling towers • L. pneumophilia • Causes a form of pneumonia called legionellosis • Survive inside aquatic amoeba

24. Coxiella • Coxiella burnetii • Q fever • Obligate intracellular pathogen • transmitted via aerosols or milk • Resistant spore–like body

25. Vibrio • Facultative anaerobic vibrio • Vibrio cholerae • Cholera • Dysentery • V. parahaemolyticus • Less severe gastroenteritis • Undercooked shellfish

26. Pasteurella • mainly pathogens of domestic animals • Cause pneumonia and septicemia • passed to humans from cat and dogbites • P. multocidia - carried by Komodo dragon

27. Haemophilus • inhabit mucous membranes of upper respiratory tract, mouth, vagina, and intestinal tract • require heme fraction (X factor) and NAD cofactor (V factor) • H. ducreyi • Chancroid (STD) • H. influenzae • meningitis, pneumonia, bronchitis, septic arthritis, earaches

28. Enterobacteriales (enterics): • Facultatively anaerobic, rods • Peritrichous flagella • Most ferment glucose and other sugars • Inhabit intestinal tract of animals (humans)

29. Escherichia Coliforms – fecal contamination UTI and Travelers Diarrhea Food poisoning – E. coli 0157:H7 Salmonella S. enterica – 2400 servors S. enterica servor typhi – typhoid fever Enterics

30. Enterics • Shigella • Shigellosis (bacillary dysentery) • Klebsiella • K. pneumoniae – serious form of pneumonia • Some species fix nitrogen

31. Yersinia Y. pestis – plague Proteus Swarmer cells UTI and wound infections Enterics

32. The  (delta) Proteobacteria • Some species are predators on other bacteria • Important contributors to the sulfur cycle

33. Bdellovibrio • Aerobic, rod with polar flagella • attack other gram (-) bacteria similar to the way a virus would

34. Desulfovibrio • Human intestinal tract and anaerobic sediments • obligate anaerobe, sulfur reducing bacteria • Use S for final electron acceptor • Release tons of H2S annually

35. Myxococcus • Gliding motility • Feed on bacteria they encounter • Cells aggregate to form fruiting body loaded with myxospores

36. The  (epsilon) Proteobacteria • Microaerophilic, helical or vibrioid rods • Motile by means of flagella

37. Campylobacter • C. fetus • causes spontaneous abortion in domestic animals • C. jejuni • leading cause of bacterial diarrhea • Helicobacter • H. pylori • common cause of stomach ulcers