BIOL2420 Chapter 11

What groups of prokaryotes are anaerobic chemolithotrophs?

Methanogens (Methanospirillum, Methanosarcina)

What are some characteristics of Methanogens?

Members of Archaea that oxidize hydrogen (H2) gas to generate ATP, using CO2 as a terminal electron acceptor to generate methane

What environments are Methanogens found in?

Sewage, swamps, marine sediments, rice paddies, digestive tracts

What groups of prokaryotes are anaerobic chemoorganotrophs that perform anaerobic respiration?

Sulfur- and sulfate-reducing bacteria (Desulfovibrio)

What are some characteristics of sulfur and sulfate-reducing bacteria?

Use sulfate as a terminal electron acceptor, generating hydrogen sulfide, which is corrosive to metals. Found in anaerobic muds rich in organic material. Gram-negative

What are the characteristics of Desulfovibrio?

Gram-negative curved rods

What groups of prokaryotes are anaerobic chemoorganotrophs that undergo fermentation?

Clostridium, Lactic acid bacteria (Streptococcus, Enterococcus, Lactococcus, Lactobacillus, Leuconostoc), Propionibacterium

What are the characteristics of Clostridium?

Endospore-forming obligate anaerobes. Inhabitants of soil. Gram-positive. Diverse metabolism, some cause diseases.

What environments are Clostridium from?

Common in soils; vegetative cells live in anaerobic microenvironments created by aerobes consuming O2

What are the characteristics of Lactic acid bacteria (Streptococcus, Enterococcus, Lactococcus, Lactobacillus, β-hemolytic S. pyogenes, S. thermophilus)?

Produce lactic acid as the major end product of their fermentative metabolism. Most can grow in aerobic environments and lack catalase, so they can only ferment. Several genera are used by the food industry. Gram-positive.

What the characteristics of Propionibacterium?

Gram-positive pleomorphic rods. Produce propionic acid via fermentation. Can also ferment lactic acid. Important in dairy industry: Swiss cheese

What groups of prokaryotes are anoxygenic phototrophs?

Purple sulfur bacteria (Chromatium, Thiospirillum, Thiodictyon); purple non-sulfur bacteria (Rhodobacter, Rhodopseudomonas); green sulfur bacteria (Chlorobium, Pelodictyon)

What are the characteristics of purple sulfur bacteria (Chromatium, Thiospirillum, Thiodictyon)?

Use sulfur compounds as a source of electrons when making reducing power. Can grow aerobically in the absence of light. Gram-negative. Large cells; some are motile, may have gas vesicles, and store sulfur in intracellular granules

What environments are purple sulfur bacteria (Chromatium, Thiospirillum, Thiodictyon) from?

Form colored (orange, red, or purple) masses in sulfur-rich aquatic habitats.

What are the characteristics of purple non-sulfur bacteria (Rhodobacter, Rhodopseudomonas)?

Preferentially uses organic compounds as a source of electrons for reducing power rather than hydrogen sulfide. Many are metabolically versatile and can grow aerobically in the absence of light using chemotrophic metabolism. Gram-negative. Lack gas vesicles and store sulfur in granules outside the cell

What environments are purple non-sulfur bacteria (Rhodobacter, Rhodopseudomonas) from?

Moist soils, bogs, paddy fields.

What are some characteristics of green sulfur bacteria (Chlorobium, Pelodictyon)?

Gram-negative. Use H2S; form sulfur granules outside of cell. Accessory pigments located in chlorosomes. Lack flagella. May have gas vesicles. Strict anaerobes. None are chemotrophic

What environments are green sulfur bacteria (Chlorobium, Pelodictyon) from?

Sulfur-rich aquatic habitats (similar to purple sulfur bacteria)

What are some characteristics of sulfur-oxidizing bacteria?

Gram-negative rods, spirals. Energy from oxidation of sulfur and sulfur compounds
including hydrogen sulfide and thiosulfate. O2 is the terminal electron acceptor; generates sulfuric acid (important in sulfur cycle)

What are the characteristics of Filamentous Sulfur Oxidizer (Beggiatoa)

Store sulfur as intracellular granules, filaments move by gliding motility

What are the characteristics of Filamentous Sulfur Oxidizer (Thiothrix)

Store sulfur as intracellular granules, filaments immobile; progeny cells detach, move via gliding motility

What groups of prokaryotes are Oxygenic Phototrophs/Cyanobacteria

Anabaena, Synechococcus

What are some characteristics of Anabaena and Synechococcus

Important primary producers. Some fix N2. Gram-negative.

What groups of prokaryotes are Aerobic Chemolithotrophs?

Sulfur-oxidizing bacteria: filamentous sulfur oxidizers, Unicellular sulfur oxidizers. Nitrifiers; Hydrogen-oxidizing bacteria.

What characteristics do Filamentous sulfur oxidizers (Beggiatoa, Thiothrix) have?

Oxidize sulfur compounds as energy sources. Found in sulfur springs and sewage-polluted waters. Gram-negative

What environments are Filamentous sulfur oxidizers (Beggiatoa, Thiothrix) from?

sulfur springs, sewage-polluted waters, surface of marine and freshwater sediments

What characteristics do unicellular sulfur oxidizers (Thiobacillus, Acidithiobacillus) have?

Oxidize metal sulfides; oxidation of gold sulfide produces sulfuric acid; lower pH converts metal to a soluble form. Some species produce enough acid to lower the pH to 1.0. Gram-negative

What environment are unicellular sulfur oxidizers (Thiobacillus, Acidithiobacillus) from?

terrestrial and aquatic habitats

What characteristics do Nitrifiers (Nitrosomonas, Nitrosococcus, Nitrobacter, Nitrococcus) have?

Gram-negative. Oxidize inorganic nitrogen compounds for energy. Concern for farmers using ammonium fertilizer. Can deplete water of 2O if wastes are high in ammonium.

What the two groups of Nitrifiers?

Ammonium oxidizers: Nitrosomonas, Nitrosococcus

Nitrite oxidizers: Nitrobacter, Nitrococcus

What characteristics do Hydrogen-oxidizing bacteria (Aquifex, Hydrogenobacter) have?

Thermophilic bacteria that oxidize hydrogen gas as an energy source. One of the earliest bacterial forms to exist on Earth. Among the few hydrogen-oxidizing bacteria that are obligate chemolithotrophs. Low O2 requirements.

What groups of prokaryotes are Aerobic Chemoorganotrophs (Obligate
Aerobes)?

Micrococcus, Mycopbacterium, Pseudomonas, Thermus, and Deinococcus

What characteristics does Micrococcus have?

Gram-positive cocci. Found in soil, dust particles, inanimate objects, and skin. Pigmented colonies. Tolerate dry, salty conditions

What characteristics does Mycobacterium have?

Acid-fast bacteria, mycolic acid in the cell wall prevents Gram staining; acid-
fast staining is used instead. Generally pleomorphic rods; many saprophytes, living on dead and decaying matter

What are notable pathogens of Mycobacterium?

M. tuberculosis, M. leprae, more resistant to disinfectants, often resistant to
antimicrobial drugs

What characteristics does Pseudomonas have?

Gram-negative rods; polar flagella; often produce pigments. Most are strict aerobes; no fermentation; oxidase-positive. Extreme metabolic diversity is important in degradation (ability sometimes from plasmids)

What environment is Pseudomonas from?

Widespread: soil, water

What characteristics does Thermus have?

Have unusual cell walls. Thermophilic; valuable for their heat-stable enzymes. Stain Gram-negative

What characteristics does Deinococcus have?

Resistant to the damaging effects of gamma radiation. Stains Gram-positive.

What groups of prokaryotes are Aerobic Chemoorganotrophs (Facultative Anaerobes)

Corynebacterium, the Enterobacteriaceae (Escherichia, Enterobacter, Klebsiella, Proteus, Salmonella, Shigella, Yersinia), Vibrio

What characteristics does Corynebacterium have?

Widespread Gram-positive pleomorphic rods. Generally facultative anaerobes; some strict aerobes. Many are harmless in normal microbiota. C. diphtheriae causes diphtheria

What are other forms of Corynebacterium?

Often club-shaped and form V-shapes or palisades. Referred to as coryneforms or diphtheroids.

What characteristics do the Enterobacteriaceae (Escherichia, Enterobacter, Klebsiella, Proteus, Salmonella, Shigella, Yersinia) have?

Known as enterics or enterobacteria. Gram-negative rods found in the intestinal tract of humans and other animals; some thrive in soil.

What Enterobacteriaceae are normal intestinal microbiota?

Enterobacter, Klebsiella, Proteus, most E. coli strains

What Enterobacteriaceae cause diarrheal disease?

Shigella, Salmonella enterica, and some E. coli strains

What Enterobacteriaceae cause typhoid fever?

Salmonella enterica serotype Typhi

What Enterobacteriaceae cause bubonic and pneumonic plague?

Yersinia pestis

What are Enterobacteriaceae lactose fermenters called?

Coliforms; include E. coli, indicator of possible fecal pollution

What characteristics does Vibrio have?

Gram-negative straight or slightly curved rods. Pathogens include V. cholerae, which causes cholera. Some are bioluminescent

What environments are Vibrio found in?

Marine environments, require some Na+ for growth

What is ecophysiology?

The study of the adaptations of physiological mechanisms that prokaryotes use to live in terrestrial and aquatic environments.

What do anaerobic chemolithotrophs do?

Oxidize inorganic chemicals for energy (ex. H2 gas) and use either CO2 or sulfur as their terminal electron acceptor.

What do anaerobic chemoorganotrophs do?

Oxidize organic compounds (ex., glucose) to obtain energy. Use sulfur or sulfate as terminal electron acceptor.

What do anoxygenic phototrophs do?

Earliest photosynthesizers. Use hydrogen sulfide or organic compounds (not water) to
make reducing power for biosynthesis; do not generate O2.

What do aerobic chemolithotrophs do?

Gain energy by oxidizing reduced inorganic chemicals.

What do aerobic chemoorganotrophs do?

Oxidize organic compounds for energy. Use O2 as the terminal electron acceptor. Some inhabit specific environments; others are ubiquitous.

Can obligate aerobes ferment?

No

Which groups/genera thrive in terrestrial environments?

Endospore formers (Bacillus, Clostridium), Azotobacter, Myxobacteria (Chondromyces, Myxococcus, Stigmatella), Streptomyces, Agrobacterium, Rhizobia (Rhizobium, Sinorhizobium, Bradyrhizobium, Mesorhizobium, Azorhizobium)

Which groups/genera thrive in aquatic environments?

Sheathed bacteria (Sphaerotilus, Leptothrix), Prosthecate bacteria (Caulobacter,
Hyphomicrobium), Bdellovibrio, Bioluminescent bacteria (Aliivibrio fischeri, Vibrio harveyi, and Photobacterium phosphoreum), Legionella, Epulopiscium, Free-living spirochetes (Spirochaeta, Leptospira (some species)), Magnetospirillum, Spirillum, Thioploca & Thiomargarita

What are the most common forms of endospore formers?

Bacillus and Clostridium (Gram positive rods)

What are Clostridium’s oxygen requirements, and what diseases can they cause?

Obligate anaerobes, C.tetani causes tetanus

What are Bacillus’s oxygen requirements, and what diseases can they cause?

Obligate and facultative anaerobes, B. anthracis causes anthrax

What types of microorganisms are Gram-negatives rods?

Bacteroides species, Bordetella pertussis, Enterobacteriaceae (Enterobacter species: Escherichia coli, Klebsiella pneumoniae, Proteus species infections, Salmonella enterica serotype Enteritidis)

What is the medical significance of the Bacteroides species?

Obligate anaerobes that commonly inhabit the mouth, intestinal tract, and genital
tract. Cause abscesses and bloodstream infections.

What is the medical significance of Bordetella pertussis?

Causes pertussis (whooping cough)

What is the medical significance of Enterobacteriaceae?

Most live in the intestinal tract.

What is the medical significance of Enterobacter species?

Normal microbiota of the intestinal tract.

What is the medical significance of Escherichia coli?

Normal microbiota of the intestinal tract. Some strains cause urinary tract infections; some strains cause specific types of intestinal disease; some cause meningitis in newborns.

What is the medical significance of Klebsiella pneumoniae?

Normal microbiota of the intestinal tract. Causes pneumonia.

What is the medical significance of Proteus species?

Normal microbiota of the intestinal tract. Cause urinary tract infections.

What is the medical significance of Salmonella enterica
serotype Enteritidis?

Causes gastroenteritis.

Grows in the intestinal tract of infected animals; acquired by consuming contaminated food.

What is the medical significance of Salmonella enterica serotype Typhi?

Causes typhoid fever. Grows in the intestinal tract of infected humans; transmitted
in feces.

What is the medical significance of Shigella species?

Cause dysentery. Grow in the intestinal tract of infected humans; transmitted in
feces.

What is the medical significance of Yersinia pestis?

Causes bubonic plague, which is transmitted by fleas, and pneumonic plague, which is transmitted in respiratory droplets of infected individuals.

What is the medical significance of Haemophilus influenza?

Causes ear infections, respiratory infections, and meningitis in children

What is the medical significance of Haemophilus ducreyi?

Causes chancroid, a sexually transmitted disease.

What is the medical significance of Legionella pneumophila?

Causes legionellosis, a respiratory disease. Grows within protozoa; acquired by inhaling contaminated water droplets.

What is the medical significance of Pseudomonas aeruginosa?

Causes burn, urinary tract, and bloodstream infections. Common in the
environment. Grows in nutrient-poor aqueous solutions. Resistant to many
disinfectants and antimicrobial medications.

What organisms are Gram-Negative Rods (Obligate Intracellular Parasites)?

Chlamydophila (Chlamydia) pneumoniae, Chlamydophila (Chlamydia) psittaci, Chlamydia trachomatis, Coxiella burnetii, Ehrlichia chaffeensis, Orientia tsutsugamushi, Rickettsia prowazekii, Rickettsia, Wolbachia pipientis

What is the medical significance of Chlamydophila (Chlamydia) pneumoniae?

Causes atypical pneumonia, or “walking pneumonia.” Acquired from an infected person.

What is the medical significance of Chlamydophila (Chlamydia) psittaci?

Causes psittacosis, a form of pneumonia. Transmitted by birds.

What is the medical significance of Chlamydia trachomatis?

Causes a sexually transmitted disease that mimics the symptoms of gonorrhea. Also causes conjunctivitis in newborns and trachoma (a serious eye infection)

What is the medical significance of Coxiella burnetii?

Causes Q fever. Acquired by inhaling organisms shed by infected animals.

What is the medical significance of Ehrlichia chaffeensis?

Causes human ehrlichiosis. Transmitted by ticks.

What is the medical significance of Orientia tsutsugamushi?

Causes scrub typhus. Transmitted by mites

What is the medical significance of Rickettsia prowazekii?

Causes epidemic typhus. Transmitted by lice.

What is the medical significance of Rickettsia?

Causes Rocky Mountain spotted fever. Transmitted by ticks.

What is the medical significance of Wolbachia pipientis?

Resides within the filarial worms that cause river blindness and elephantiasis.

What organisms are Gram-Negative Curved Rods?

Campylobacter jejuni, Helicobacter pylori, Vibrio cholera, Vibrio parahaemolyticus, Vibrio vulnificus

What is the medical significance of Campylobacter jejuni?

Causes gastroenteritis. Grows in the intestinal tract of infected animals; acquired by consuming contaminated food.

What is the medical significance of Helicobacter pylori?

Causes peptic ulcers. Neutralizes stomach acid by producing urease

What is the medical significance of Vibrio cholera?

Causes cholera, a severe diarrheal disease; acquired by drinking contaminated water

What is the medical significance of Vibrio parahaemolyticus?

Causes gastroenteritis. Acquired by consuming contaminated seafood.

What is the medical significance of Vibrio vulnificus?

Causes a systemic disease, particularly in people who have liver failure or other underlying complications.

What organisms are Gram-Negative Cocci?

Neisseria meningitides, Neisseria gonorrhoeae

What is the medical significance of Neisseria meningitides?

Causes meningitis.

What is the medical significance of Neisseria gonorrhoeae?

Causes gonorrhea, a sexually transmitted infection.

What organisms are Gram-positive rods?

Bacillus anthracis, Bifidobacterium species, Clostridium botulinum, Clostridium perfringens, Clostridium tetani, Clostridium difficile, Corynebacterium diphtheria

What is the medical significance of Bacillus anthracis?

Causes anthrax. Acquired by inhaling endospores in soil, animal hides, and wool. Also acquired by touching or ingesting the endospores. Bioterrorism agent.

What is the medical significance of Bifidobacterium species?

Predominant member of the intestinal tract in breast-fed infants. Thought to play a protective role in the intestinal tract by excluding pathogens.