Enhancement of Propagation of Mycoplasma Hyopneumoniae by Culture in a Biphasic Medium

Fischer, 0.: Enhancement of Propagation of Mycoplasma hyopneumoniae by Culture in a Biphasic Medium. Acta vet. Bmo, 1995,64:243-247. Mycoplasma hyopneumoniae (strain J) was propagated in a liquid and a biphasic media. The solid phase of the biphasic medium was obtained by the addition of 1.9% or 0.19% of agar to the liquid medium. Compared with the liquid medium, a more rapid propagation of mycoplasmas was observed in the biphasic medium after two weeks of incubation. After three weeks of incubation in the liquid and the biphasic medium containing 0.19% of agar in the solid phase, the numbers of mycoplasmas rose 2.7fold and 4.7fold, respectively. The biphasic medium, simulating partly the environment of the porcine respiratory tract, supported better the propagation of M. hyopneumoniae than the liquid medium. The biphasic medium containing 0.19% of agar in the solid phase should be preferred when a mass of Mycoplasma cells is to be obtained. Porcine enzootic pneumonia, culture media, biomass The causal agent of porcine enzootic pneumonia Mycoplasma hyopneumoniae ranks with Mycoplasma species which are difficult to propagate (Friis 1975, 1979). On solid media, this species does not form the "fried eggs" colonies typical of a majority of mycoplasmas, but rather small, dispersed bodies resembling poppy-seeds. The propagation in liquid media is very slow, taking several weeks. Larger amounts of Mycoplasma cells can be obtained only by gradually increasing the volume of the culture medium (Kuksa et al. 1987). M. hyopneumoniae lives on the surface of porcine respiratory mucosae (MeyIing 1971; Kobisch et al. 1993). The mucus of the respiratory tract protects M. hyopneumoniae cells from drying in the environment thus supporting the spread of porcine enzootic pneumonia by droplet infection (Goodwin 1972; Friis 1973). As a typical mucosal pathogenic agent, M. hyopneumoniae is adapted to an environment which is more viscous than are the conventional liquid media used for its culture in vitro. A biphasic culture medium, simulating partly the conditions prevailing in the porcine respiratory tract, was used to provide more favourable conditions for the culture of M. hyopneumoniae in vitro. Materials and Methods The strain] of Mycoplasma hyopneumoniae (type strain NCI'C 10110, ATCC 25934) was obtained from the Collection of Animal Pathogenic Microorganisms, Bmo (CAPM M-38).The biphasic culture medium consisted of solid and liquid phases. Liquid phase The medium FF (Friis, 1971) was modified as follows: Saline A: 160 g NaCI, 8 g KCI, 2 g MgS04.7H20, 2 g MgC~.6H20, and 2.8 g anhydrous CaC~ were dissolvt;ld in 1 L bidistilled water. Saline B: 3 g N~HP04.12~0 and 1.2 g ~P04 were dissolved in 1 L bidistilled water.