Microbiology - Prokaryotes

• THE PROKARYOTES
• Domain Bacteria: The 4 phyla

  • Proteobacteria
  • Gram-positive bacteria
  • Non-proteobacteria Gram-negative bacteria
  • Fusobacteria
• Proteobacteria: 5 classes

  • Alphaproteobacteria
  • Betaproteobacteria
  • Gammaprobacteria
  • Deltaprobacteria
  • Epsilonprobacteria
• Proteobacteria

  • Largest taxonomic group of bacteria
  • Most of the Gram-negative chemoheterotrophic bacteria included

  
• Proteobacteria

  Named after Proteus, a Greek god of the sea, capable of assuming many different shapes
• Alphaproteobacteria


  • Pelagibacter
  • Rickettsia
  • Ehrlichia
  • Brucella
  • Bartonella
  • Azospirillum
  • Acetobacter & Gluconobacter
  • Caulobacter &Hyphomicrobium
  • Rhizobium, Bradyrhizobium & Agrobacterium
  • Nitrobacter & Nitrosomonas
  • Wolbachia
• Alphaproteobacteria


  • Includes most of the proteobacteria that are capable of growth at very low levels of nutrients
  • Includes agriculturally important bacteria capable of inducing nitrogen fixation in symbiosis with plants
  • Also includes several plant and human pathogens
• Pelagibacter ubique


  One of the most abundant microorganisms on Earth, especially in the Ocean environment
• Rickettsia


  • Gram-negative bacilli or coccobacilli
  • Transmitted to humans by bites of insects or ticks
  • Obligate intracellular parasite of phagocytes
• Diseases caused by Rickettsia


  Spotted fevers such as the epidemic typhus (lice), & Rocky Mountain spotted fever (tick)
• Ehrlichia


  • Gram-negative rickettsia-like bacteria
  • Obligate intracellular parasite of white blood cells (WBCs) but does not cause spotted fevers
  • Transmitted by ticks through bites
  • A sometimes fatal disease in humans and dogs that can lead to fever, rash, and bleeding
• Bartonella


  • Gram-negative bacilli known to cause human disease such as the CAT SCRATCH DISEASE
  • Transmitted by fleas & ticks to cats, and transmitted to humans through cat scratch or bite
• Brucella


  • Small non-motile coccobacilli
  • Transmitted from infected animals or unpasteurized animal products (e.g. milk)
  • Obligate parasites of mammals – Able to survive phagocytosis
• Brucellosis


  Animals that are most commonly infected include sheep, cattle, goats, pigs, and dogs, among others
• Betaproteobacteria


  • Burkholderia
  • Bordetella
  • Neisseria
  • Thiobacillus
  • Spirillum
  • Sphaerotilus
  • Zooglea
• Burkholderia


  • Aerobic gram-negative motile flagellated bacilli
  • Complicates conditions of people with the genetic lung disease cystic fibrosis
  • Capable of degrading more than 100 different organic molecules
  • Can grow on respiratory secretions in the lung
  • Can even grow in disinfectant!
• Bordetella


  • Non-motile aerobic, gram negative bacillus
  • Causes pertussis (whooping cough)
• Neisseria


  • Aerobic, gram-negative diplococci that usually inhibit the mucous membranes of mammals
  • Neisseria gonorrhoeae causes gonorrhea (sexually transmitted disease)
  • Neisseria meningitidis causes meningococcal meningitis
• Gonorrhea


  Sexually transmitted disease characterized by pain and discharge from the urethra ("tulo")
• Gammaproteobacteria

  • Francisella
  • Pseudomonadales (Pseudomonas)
  • Vibrionales (Vibrio)
  • Enterobacteriales (Escherichia, Salmonella, Shigella, Klebsiella, Serratia, Proteus, Enterobacter)
  • Pasteurellales (Pasteurella, Haemophilus)
• Francisella


  • Small pleomorphic bacteria that grow on complex media enriched with blood or tissue extracts
  • Causes tularemia (rabbit fever; rodent fever) with swollen/painful lymph nodes
• Pseudomonas aeruginosa


  • Aerobic gram-negative bacilli with polar flagella
  • Produces a blue-green pigmentation on culture media
  • Can infect the urinary tract, burns, wounds, and can cause blood infections (sepsis), abscesses, and meningitis
  • Also cause of drug-resistant hospital-acquired infections
• Legionella


  • Thin non-capsulated bacilli that poorly staining gram-negative bacteria
  • Difficult to grow on usual culture media
  • Common in steam and warm-water supply lines and air-conditioning systems

  
• Legionnaire's disease


  • Legionella was discovered after an outbreak in 1976 among people who went to a Philadelphia convention of the American Legion
  • Those who were affected suffered from a unique type of pneumonia
• Vibrio


  • Facultatively anaerobic gram-negative curved rods found mostly in aquatic habitats
  • Vibrio cholerae causes the disease cholera
  • Transmitted by ingestion of raw or undercooked shellfish in waters contaminated by vibrios
  • Acute diarrheal disease characterized by profuse and watery diarrhea with stools appearing like rice-water
• Enterobacteriales (Enterics)


  • Escherichia (E.coli)
  • Salmonella
  • Shigella
  • Klebsiella
  • Serratia
  • Proteus
  • Yersinia
• Escherichia coli (E.coli)


  • One of the most common inhabitants of the human intestinal tract, and commonly used in laboratory experiments
  • E. coli is usually NOT pathogenic, but can cause urinary tract infection, traveller's diarrhea, and hemolytic uremic syndrome (HUS)
• Salmonella


  • Common inhabitants of intestinal tracts of many animals especially poultry & cattle
  • Almost all members of this genus are pathogenic
  • Can contaminate food, especially raw eggs
• Salmonella enterica


  • Instead of having multiple species, infectious members are all considered Salmonella enterica
  • This species is divided into 2400 serovars including S. typhimurium, S. bongori, and S. typhi
• Typhoid fever


  • Most severe illness caused by any Salmonella
  • Foodborne illness, caused by ingestion of food or water contaminated by fecal material containing S.typhi
  • Characterized by high fever, severe abdominal pain & diarrhea (sometimes with rash)
• Typhoid Mary was an asymptomatic carrier of typhoid fever who is believed to have infected 53 people, three of whom died
• Shigella


  • Responsible for bacillary dysentery or shigellosis with bloody diarrhea, abdominal pain, and can be life threatening
  • Only found in humans
  • Short bacilli/coccobacilli
• Klebsiella


  • Species commonly found in soil or water, and able to fix nitrogen
  • Klebsiella pneumoniae is a common cause of serious form of pneumonia
• Serratia marcescens


  • Bacterial species distinguished by production of a red pigment
  • Glycocalyx allows the bacteria to form biofilms on catheters or certain sterile solutions

  
• Proteus


  • Swarmer bacilli with peritrichous flagella
  • Swarming colony showing concentric rings as they move outward, twitching motality
  • Implicated in urinary tract & wound infections
• Yersinia pestis


  • Causative agent of the bubonic plague that caused the Black Death of medieval Europe
  • Disease spread by urban rats & squirrels through fleas to humans
• Haemophilus


  • Pathogenic bacteria that inhabit the mucus membranes of the upper respiratory tract
  • Require blood in culture medium to obtain parts of cytochrome for cellular respiration
  • Haemophilus influenzae is a common cause of bacterial meningitis in children, ear infections, epiglottitis, bronchitis, and pneumonitis
• Haemophilus influenzae does not cause influenza!
• Deltaproteobacteria


  • Includes bacterial species that act as predators of other bacteria
  • Includes important contributors in the sulfur cycle
• Epsilonproteobacteria


  • Slender gram negative rods that are helical/curved
  • Include Campylobacter and Helicobacter