Upload
brian-bennett
View
251
Download
1
Tags:
Embed Size (px)
Citation preview
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 11.25
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. hensela Cat-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. prowazekii Epidemic typhus
• R. typhi Endemic murine typhus
• R. rickettsii Rocky Mountain Spotted Fever
The (alpha) Proteobacteria
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 CO2 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 (H2S SO42–)
• 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
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 H2S to S0 for
energy
• Francisella– Chemoheterotrophic, tularemia
The (gamma) Proteobacteria
• Actinomyces
• Corynebacterium
• Frankia
• Gardnerella
• Mycobacterium
• Nocardia
• Propionibacterium
• Streptomyces
Actinobacteria
Figure 11.20b
• Actinomyces
• Corynebacterium
• Frankia
• Gardnerella
• Mycobacterium
• Nocardia
• Propionibacterium
• 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 O2 as final electron acceptor
• Release millions of tons of H2S 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
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