Bacterial Replication

Binary fission- copyright J W Schmidt

Replication normally occurs by binary fission and ranges from every 20 mins (e.g. Staphylococci) to 2 weeks (e.g. leprosy bacillus)

• Variation can occur either by mutations in their DNA, or by lateral gene transfer:
  • Transformation- small, naked pieces of DNA are directly transferred between bacteria, e.g. S pneumoniae
  • Transduction- viruses known as bacteriophages transfer the DNA, many genes encoding toxins are transferred this way
    

    Conjugative plasmids- copyright Magnus Manske
  • Conjugation- DNA is transferred in the form of plasmids, genes encoding antibiotic resistance are typically transferred this way.

Typical requirements of bacteria

• Atmospheric requirements:
  • Obligate aerobe- e.g. B. bronchoseptica
  • Facultative (optional) anaerobe-e.g. E. coli
  • Obligate anaerobe- e.g. F. necrophorum
  • Microaerophil- e.g. C. jejuni
  • Aerotolerant- e.g. S. dysgalactiae
• pH- most pathogens require a neutral pH, although some need acidic/alkali environments:
  • Acidophilic- Lactobacillus
  • Alkophilic- Vibrio

Replication of E. coli [1]