Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 1

The Prokaryotes: Domains Bacteria and Archaea One circular chromosome (no histones), not in a membrane (no nucleus) No organelles 70S ribosomes Peptidoglycan cell walls (mainly bacteria) Binary fission

Domain Archaea Discovered in late 1970s; highly diverse group rRNA sequence differ from Domains Bacteria & Eukarya Cell wall lacks peptidoglycan; a few lack cell wall Some are gram-positive and some are gram- negative

Binary fission, fragmentation or budding Most are morphologically similar to bacteria (rods, cocci, and helixes); but some are very unusual Domain Archaea Figure Disk-shaped Pyrodictium abyssi

Domain Archaea Physiologically diverse (aerobic, facultative anaerobe, and strict/obligate anaerobe) Chemoautotrophs, photoautotrophs, and chemoheterotrophs Frequent inhabitants of extreme environments (heat, cold, acidity, and pressure)

Domain Archaea Hyperthermophiles –Pyrodictium –Sulfolobus Methanogens (economic importance) –Methanobacterium derive energy from combining hydrogen with carbon dioxide to form methane Extreme halophiles –Halobacterium –Halococcus

Domain Bacteria Proteobacteria –Mythical Greek god, Proteus, who could assume many shapes –Gram-negative; many are chemoheterotrophic bacteria –presumed to have arisen from a common photosynthetic ancestor; few are photosynthetic today The alpha (  ) proteobacteria –As a group, most are capable of growth at very low levels of nutrients

The  (alpha) Proteobacteria Chemoautotrophs and chemo- heterotrophs Include agriculturally important bacteria, and several plant and human pathogens

Some have unusual morphology prosthecae: protrusions such as stalks or buds –Caulobacter. Stalked bacteria found in lakes –Hyphomicrobium. Budding bacteria found in lakes The  (alpha) Proteobacteria Figure 11.2 & 3

Human pathogens: –Bartonella: several members are human pathogens B. henselaCat-scratch disease –Brucella: small nonmotile coccobacilli; obligate parasites of mammals and cause diseases brucellosis The  (alpha) Proteobacteria

Obligate intracellular parasites: reproduce only within a mammalian cell –Ehrlichia: tick-borne, cause ehrlichiosis –Rickettsia: arthropod-borne (e.g. lice, rat fleas, and ticks), cause spotted fevers R. prowazekiiEpidemic typhus R. typhiEndemic murine typhus R. rickettsiiRocky Mountain Spotted Fever The  (alpha) Proteobacteria

Figure 11.1

Wolbachia. Live in insects and other animals –infect over a million species of insects as well as spiders, millipedes, mites, crustaceans, and nematodes. The  (alpha) Proteobacteria

Plant pathogen: –Agrobacterium tumefaciens causes a disease called crown gall by inserting a (Ti) plasmid into plant cells, & inducing a tumor The  (alpha) Proteobacteria Figure 9.17

Agriculturally important genera (Nitrogen-fixing & nitrifying bacteria) –Azospirillum Grow in soil, using nutrients excreted by plants Fix nitrogen –Rhizobium Fix nitrogen in the roots of plants The  (alpha) Proteobacteria Figure 27.5

–Nitrobacter oxidize nitrogen (ammonium to nitrite) for energy –Nitrosomonas oxidize nitrogen (nitrite to nitrate) for energy –Both are chemoautotrophic (fix CO 2 as C source). Important for the environment and to agriculture Industrially important genera –Acetobacter Both produce acetic acid –Gluconobacter from ethyl alcohol The  (alpha) Proteobacteria

The  (beta) Proteobacteria Considerable overlap between the  - and  - proteobacteria, esp. among the nitrifying bacteria Many use nutrient substances that diffuse away form areas of anaerobic decomposition of organic matter Chemoautotrophs & chemoheterotrophs Include several important pathogenic bacteria

The  (beta) Proteobacteria

Human pathogens –Neisseria : chemoheterotrophic, cocci N. meningitidis N. gonorrhoeae –Bordetella: chemo- heterotrophic, rods B. pertussis –Burkholderia: cause nosocomial infections The  (beta) Proteobacteria Figure 11. 6

The  (beta) Proteobacteria Sphaerotilus –Chemoheterotophic –form sheaths –Cause problem in sewage treatment Spirillum –Chemoheterotrophic –Helical shaped, but use flagella (no axial filaments) Figures 11.4 & 11.5

Environmentally important genera –Thiobacillus: Chemoautotrophic, important in sulfur cycle by oxidizing sulfur (H 2 S  SO 4 2– ) Industrially important genera –Zoogloea: Slimy masses in aerobic sewage- treatment processes The  (beta) Proteobacteria

The  (gamma) Proteobacteria Largest subgroup of the proteobacteria; include a great variety of physiological types Many are human and plant pathogens

The  (gamma) Proteobacteria

Pseudomonadales: –Pseudomonas Opportunistic pathogens Metabolically diverse Polar flagella –Azotobacter and Azomonas: Nitrogen fixing –Moraxella: Conjunctivitis The  (gamma) Proteobacteria Figure 11.7

Legionellales: –Legionella Found in streams, warm-water pipes, cooling towers L. pneumophilia –Coxiella Q fever transmitted via aerosols or milk The  (gamma) Proteobacteria Figure 24.15b

Vibrionales: –Found in coastal water Vibrio cholerae causes cholera V. parahaemolyticus causes gastroenteritis The  (gamma) Proteobacteria Figure 11.8

The  (gamma) Proteobacteria –Enterobacteriales (enterics): Peritrichous flagella, facultatively anaerobic –Enterobacter –Erwinia –Escherichia –Klebsiella –Proteus –Salmonella –Serratia –Shigella –Yersinia The  (gamma) Proteobacteria

Figure 11.9a, b

Pasteurellales: –Pasteurella Cause pneumonia and septicemia –Haemophilus Require X (heme) and V (NAD +, NADP + ) factors The  (gamma) Proteobacteria

Beggiatoa –Chemoautotrophic, oxidize H 2 S to S 0 for energy Francisella –Chemoheterotrophic, tularemia The  (gamma) Proteobacteria

Actinomyces Corynebacterium Frankia Gardnerella Mycobacterium Nocardia Propionibacteriu m Streptomyces Actinobacteria Figure 11.20b

Actinomyces Corynebacterium Frankia Gardnerella Mycobacterium Nocardia Propionibacteriu m Streptomyces Actinobacteria Figure 11.20b

The  (delta) Proteobacteria Include some bacteria that are predators on other bacteria. Contributors to the sulfur cycle

–Bdellovibrio: prey on other gram-negative bacteria –Desulfovibrionales: sulfur reducing bacteria; use S instead of O 2 as final electron acceptor Release millions of tons of H 2 S into the atmosphere every year and plays a key part in the sulfur cycle –Myxococcales: gliding; cells aggregate to form myxospores; also predatory on other bacteria The  (delta) Proteobacteria

Figure 11.10a

The  (delta) Proteobacteria Figure 11.1b

The  (epsilon) Proteobacteria Slender gram-negative rods; helical or vibroids

Vibroid: helical bacteria that do not have a complete turn Human pathogens –Campylobacter: one polar flagellum; microaerophilic vibrios; cause gastroenteritis C. fetus C. jejuni The  (epsilon) Proteobacteria Figure 11.1a

–Helicobacter: multiple flagella; microaerophilic curbed rods H. pylori causes peptic ulcers & Stomach cancer The  (epsilon) Proteobacteria Figure 11.11