Effect of moisture content of the medium on colony morphology of Campylobacter fetus subsp. jejuni.

Reduction in the moisture content of the medium produced a profound effect on the colony morphology of Campylobacter fetus subsp. jejuni. Fresh medium produced flat, grayfish, spreading colonies with an irregular shape and variety appearance. Plates that were incubated at 30 degrees C for 48 h produced round, convex, butyrous colonies with an entire edge. Plates incubated at 30 degrees C for 24 h before inoculation produced colonies of an intermediate nature; they were round and raised, but not convex, and slightly water or mucoid in nature. This marked effect produced by moisture content of the medium was reproducible and may account for the variation in colonies observed by other investigators.