Cultural characteristics

CULTURAL CHARACTERISTICS

  • It is a facultative anaerobe, but growth is enhanced by 10% C02.
  • It is able to grow in a temperature range of 5ºC to 42ºC, within a pH range 6.7 to 9.2 and 8% NaCl2.
  • Growth occurs on nutrient agar but is improved by the addition of serum or blood. It will not grow on Mac Conkey agar.
  • Media contain either sodium azide (0.1%) or crystal violet (0.001%) may be used as selective media.
  • On blood agar, non-haemolytic pinpoint colonies (0.5 mm) appear at 24 hrs incubation.
  • Colonial variation becomes obvious at 48 hrs incubation when a zone of greenish haemolysis often develops under and just around the colonies.
  • The smooth form colonies are convex, circular with an entire edge.
  • The large rough form colonies are flatter, more opaque and have an irregular edge.
  • A characteristic reaction is produced when triple sugar iron agar is stab inoculated.
  • When incubated at 37ºC for 24 hrs H2S is produced as a thin, black line just along the inoculation stab.
  • The R forms gives a bottle-brush type of growth in stab cultures of gelatin incubated at 21ºC for 5 days.
Last modified: Monday, 4 June 2012, 4:52 AM