Finals-Microbio

• Endosymbiotic theory


  States that eukaryotic cells evolved from prokaryotic cells living inside one another as endosymbionts
• Endosymbiosis


  • We need each other
• The three domains


  • Bacteria
  • Archaea
  • Eukarya

  
• Phyla of domain Bacteria


  • Proteobacteria
  • Gram-positive Bacteria
  • Cyanobacteria
  • Chlamydiae
  • Planctomycetes
  • Bacteroides
  • Fusobacteria
  • Spirochaetes
  • Purple & Green Bacteria
  • Deinococci

  
• Proteobacteria


  Largest taxonomic group of bacteria, most of the Gram-negative chemoheterotrophic bacteria included
• Proteobacteria


  • Named after Proteus, Greek god of the sea, who is capable of assuming many different shapes
  • Separated into 5 classes
• Alphaproteobacteria


  • Most of the proteobacteria capable of growth at very low levels of nutrients
  • Some agriculturally important bacteria capable of inducing nitrogen fixation in symbiosis with plants
  • Also includes several plant and human pathogens
• Pelagibacter (Pelagibacter ubique)


  One of the most abundant microorganisms on Earth, found in the ocean environment
• Rickettsia


  • Gram-negative bacilli or coccobacilli
  • Transmitted to humans by bites of insects or ticks
  • Obligate intracellular parasite of phagocytes (enter host cell by inducing phagocytosis)
  • Causes spotted fevers like epidemic typhus and Rocky Mountain spotted fever

  
• 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
  • Causes Ehrlichiosis, a sometimes fatal disease in humans and dogs that leads to fever, rash and severe bleeding

  
• Bartonella


  • Gram-negative bacilli known to cause human diseases such as the cat scratch disease
  • Transmitted by fleas and 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)
  • Causes Brucellosis, a disease that infects animals like sheep, cattle, goats, pigs, and dogs
• Betaproteobacteria


  • Group of bacteria that often use nutrient substances that diffuse away from areas of anaerobic decomposition of organic matter
  • Includes several pathogenic bacteria
• Burkholderia


  • Aerobic gram-negative motile flagellated bacilli
  • Complicates conditions of those with the genetic lung disease, cystic fibrosis
  • Burkholderia cepacia is capable of degrading more than 100 different organic molecules, can grow on respiratory secretions in the lung, and can even grow in disinfectants
• 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 infection characterized by pain and discharge from the urethra (tulo)
• Gammaproteobacteria


  • Largest subgroup of proteobacteria
  • Includes pathologic bacteria
• 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, also known as rabbit fever or rodent fever, which leads to swollen/painful lymph nodes

  
• Pseudomonas


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


  • Thin non-capsulated poorly staining gram-negative bacteria
  • Difficult to grow on usual culture media
  • Common in steam and warm-water supply lines and air-conditioning systems
  • Causes a unique type of pneumonia discovered after an outbreak in 1976 among people who went to a Philadelphia convention of the American Legion
• Vibrio


  • Facultatively anaerobic gram-negative curved rods found mostly in seawater habitats
  • Vibrio cholerae causes the disease cholera, which is transmitted by ingestion of raw or undercooked shellfish in waters contaminated by vibrios
• Cholera


  Acute diarrheal disease characterized by profuse and watery diarrhea with stools appearing like rice-water
• Enterobacteriales (Enterics)


  • Gram-negative bacilli, facultatively anaerobic, and active fermenters of glucose and other carbohydrates
  • Inhabit the intestinal tracts of humans, animals
  • Have peritrichous flagella and sex pili
• Escherichia coli (E.coli)


  • One of the most common inhabitants of the human intestinal tract, and commonly used in laboratory experiments
  • Usually NOT pathogenic but can cause urinary tract infection, traveller's diarrhea, and hemolytic uremic syndrome (HUS)
  • Gram-negative (pink staining) bacillus

  
• Salmonella


  • Common inhabitants of intestinal tracts of many animals especially poultry, cattle
  • Almost all members of this genus are pathogenic (flagella, capsule and cell wall can act as antigens)
  • Can contaminate food, especially raw eggs
  • Salmonella enterica refers to all members of Salmonella capable of causing infection, divided into 2400 serovars
  • Typhoid Fever is the most severe illness caused by any Salmonella, a 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)
• Shigella


  • Responsible for bacillary dysentery or shigellosis, causing 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 a serious form of pneumonia
• Serratia

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

  
• Proteus

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


  • Yersinia pestis is the 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
  • Haemo- = requires blood in culture medium to obtain parts of cytochrome for cellular respiration
  • Clinically important species include Haemophilus influenzae, responsible for several important diseases like bacterial meningitis in children, ear infections, epiglottitis, bronchitis, and pneumonitis (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
  • Includes Campylobacter, microaerophilic vibrios that cause fetal abortions in animals (Campylobacter fetus) and foodborne intestinal diseases (Campylobacter jejuni)
  • Also includes Helicobacter, microaerophilic vibrios with multiple flagella, most common cause of peptic ulcers in humans (Helicobacter pylori)

  
• Phylum #2: Gram Positive Bacteria

  • Firmicutes (low G+C ratios)
  • Actinobacteria (high G+C ratios)
• Firmicutes (Low G+C) Gram Positives


  • Group of gram-positive bacteria that have less than 50% of G+C ratio
  • Includes endospore-formers Clostridium & Bacillus, Staphylococcus, Streptococcus, Enterococcus, Lactobacillus, Mycoplasma
• Clostridium


  • Genus of obligate anaerobic bacilli that contain endospore that distends the cell
  • C. tetani (tetanus) thrive in solid and rusty metals and cause fatal diseases
  • C. botulinum (botulism) is a contaminant of canned food, wounds and infant umbilicus, causing fatal neurological disease
• Bacillus


  • Gram-positive rods that produce endospores, common in the soil
  • Few species are clinically significant like Bacillus anthracis (anthrax, biological warfare), Bacillus thuringensis (BT crops), and Bacillus cereus (food poisoning, reheated fried rice)
  • Anthrax is a deadly disease causing skin changes such as itchy bumps or sores/ulcers with a black center
• Staphylococcus


  • Gram-positive cocci occurring as grape-like clusters and mostly facultative anaerobes
  • Grow well under conditions of high osmotic pressure and low moisture, found in skin and nasal secretions, ham and cured meats
  • Includes the significant Staphylococcus aureus, whose golden yellow-pigmented colonies possibly confer protection from sunlight
  • Produces toxins that increase its ability to invade or damage the body, causing various diseases like surgical wound infection, food poisoning, and toxic shock syndrome