Biphasic culture of Arcobacter spp.

Arcobacter spp. have recently been genetically differentiated as a genus distinct from Campylobacter. Physiologically, Arcobacter spp. are aerotolerant bacteria, while Campylobacter spp. are microaerophilic. However, since Arcobacter spp. have been difficult to grow to high population densities in broth media, alternative culture techniques were investigated. A biphasic culture system was developed in 25 cm2 tissue culture flasks. Biphasic culture, consisting of a solid phase of 10% bovine blood agar and a liquid phase of Brain Heart Infusion broth, was found to increase bacterial population densities by more than 2 log10 cycles for strains of A. butzleri and A. skirrowii. A strain of A. cryaerophilus, which was non-culturable in broth culture, attained population densities of 10(9) cells ml-1 in biphasic culture. Neither the addition of fetal bovine serum to the liquid nor an increase in the surface area from 25 to 75 cm2 resulted in increased cell densities.