Bacillus

• What are the main genera of endospore-forming bacteria?

  Bacillus and Clostridium
• What type of anaerobes are Bacillus and Clostridium?

  Bacillus are aerobic/facultative anaerobes, while Clostridium are anaerobic
• What is an endospore?

  An endospore is a distinctive type of dormant cell formed by certain bacteria
• Under what conditions are endospores usually formed?

  Endospores are usually formed when a population reaches conditions of nutrient limitation
• What are the resistance properties of endospores?

  Endospores are highly resistant to heat, UV, toxic chemicals, and ionizing radiation
• What type of cell wall do endospore formers typically have?

  They have a typical Gram-positive cell wall but stain variably
• What is the typical habitat of endospore formers like Bacillus?

  The typical habitat is soil
• What is the sporulation cycle of Bacillus?

  1. Binary fission in vegetative state
  2. Asymmetric cell division forms a pre-spore
  3. Mother cell engulfs pre-spore, creating multiple protective layers
  4. Dehydration occurs, reducing water content to 10-30%
  5. Mother cell degrades, leaving the germination spore
• What is the exosporium in the spore structure?

  The exosporium is a thin delicate layer of mostly protein
• What is the composition of the spore coat?

  The spore coat consists of multiple layers of spore-specific proteins
• What is the function of dipicolinate in the core of the endospore?

  Dipicolinate protects DNA and constitutes about 10% of the spore's mass
• How does dehydration affect the endospore's resistance?

  Dehydration gives the endospore heat and stress resistance
• What is the pH level of the core compared to the vegetative cell?

  The pH of the core is more acidic than that of the vegetative cell
• What role do small acid-soluble spore proteins (SASPs) play in endospores?

  SASPs provide resistance to dry heat, desiccation, and UV, protecting DNA
• What are the characteristics of dormant endospores?

  • Low metabolic activity
  • No macromolecular synthesis
  • Low enzymatic activity
  • Low or absent mRNA synthesis
• How long can endospores remain dormant?

  Endospores can remain dormant for decades
• What treatments can activate dormant spores?

  Heat shock or storage at low temperatures can activate dormant spores
• What happens when activated spores are placed in favorable conditions?

  They germinate and grow out of the spore coat to enter the vegetative state
• What is the longevity of endospores?

  Endospores are extremely stable and can survive for long periods
• What is the significance of the 1995 discovery regarding spores?

  Spores were revived from the gut of a bee preserved in fossil amber, estimated to be 25-40 million years old
• What is the relationship between sequenced rRNA genes and Bacillus sphaericus?

  Sequenced rRNA genes are related to extinct Bacillus sphaericus
• What is Bacillus anthracis known for?

  Bacillus anthracis is the agent of anthrax
• How does Bacillus anthracis affect livestock?

  It causes disease in sheep, goats, and cattle
• Who isolated Bacillus anthracis and when?

  Koch isolated it in 1877 as the first bacterial pathogen
• How long can Bacillus anthracis spores survive in soil?

  Bacillus anthracis spores can survive in soil for 30 years or more
• What is the most common form of anthrax?

  Cutaneous anthrax
• How do spores cause cutaneous anthrax?

  Spores germinate in skin abrasions, leading to skin ulcers
• What is the mortality rate of untreated cutaneous anthrax?

  The mortality rate is 20% if untreated
• What causes gastrointestinal anthrax?

  It is caused by the ingestion of undercooked contaminated meat
• What are the symptoms of abdominal gastrointestinal anthrax?

  Symptoms include nausea, severe abdominal pain, vomiting, and bloody diarrhea
• What are the usual causes of death in gastrointestinal anthrax?

  Intestinal perforation or anthrax toxemia are usual causes of death
• How does pulmonary anthrax occur?

  It occurs through the inhalation of spores
• What happens to spores in the lymph nodes during pulmonary anthrax?

  Some spores are trafficked to the draining lymph nodes and may germinate there
• What are the symptoms of pulmonary anthrax?

  Symptoms include flu-like symptoms, fever, cough, and chest pain
• What is the mortality rate of inhalational anthrax in unvaccinated individuals?

  The mortality rate is 99% in unvaccinated individuals
• What are the virulence factors of Bacillus anthracis?

  • Capsule made of poly-D-glutamate polypeptide
  • Toxin encoded on plasmid pX01 with three parts:
  • PA (binding domain)
  • EF (edema factor)
  • LF (lethal factor)
• How was Bacillus anthracis tested as a biological warfare agent?

  It was tested on Gruinard Island during WW2, leading to sheep deaths
• What was the outcome of the Gruinard Island testing?

  The island was eventually decontaminated
• What is the required caution when handling Bacillus anthracis samples?

  Extreme caution is required when handling samples
• What are the treatments for Bacillus anthracis infection?

  Penicillin, doxycycline, and fluoroquinolones