[Investigation on growth media for Mycoplasma: evaluation of infusions, peptones, sera, yeast extracts and other supplements]

Survival of mycoplasmas inoculated in horse sera

Although it is known that commercialized bovine serum is sometimes contaminated with mycoplasmas, it is not clear whether mycoplasmas can survive in horse serum. In this study, as a preliminary examination of the survival of mycoplasmas inoculated in horse sera, the survivability of 8 strains of 7 mycoplasmas was tested. The results obtained reveal that two strains of M. bovis and M. gallisepticum were found to survive in non-heated and inactivated sera for 94 to 330 days at 30 or 37 degrees C. Three strains of M. bovirhinis, M. gateae and A. laidlawii lived for 7 to 330 days depending upon the temperature maintained or pH of the serum. Strains of M. bovigenitalium and U. diversum survived for a maximum of 8 days in all horse sera tested. Therefore, mycoplasmas are generally likely to survive for a long period in horse serum although the survival period depends on the species, strain and temperature.

Comparison of Chalquest and Hayflick media, with and without ammonium reineckate, for isolating Mycoplasma pulmonis from rats

Chalquest and Hayflick media with and without ammonium reineckate were compared for isolation of Mycoplasma pulmonis from the nasopharyngeal ducts, tracheobronchial trees, and middle ears of 66 naturally infected rats. The results show that 92% (366 of 396) of the samples were positive for M. pulmonis in Chalquest medium with and without ammonium reineckate and 66% (260 of 396) were positive in Hayflick medium with and without ammonium reineckate (P less than 0.001). An enhancing effect of ammonium reineckate on M. pulmonis isolation was observed only in Hayflick medium; the isolation rate was 76% (151 of 198) in Hayflick medium with ammonium reineckate as compared with 55% (109 of 198) in Hayflick medium without ammonium reineckate (P less than 0.03). No significant differences in isolation rates were observed between Chalquest medium with and without ammonium reineckate. The mean growth time of M. pulmonis on Chalquest medium was 3.4 days as compared with 5.1 days in Hayflick medium, indicating that M. pulmonis can be detected earlier on Chalquest medium than on Hayflick medium. These data indicate that Chalquest medium is superior to Hayflick medium for M. pulmonis isolation from rats.

Comparison of the efficacy of egg yolk extract and horse serum for growth of Mycoplasma pneumoniae

The usefulness of chicken egg yolk extract as a substitute for horse serum in culture media for Mycoplasma pneumoniae was investigated. As a growth-supporting factor in the growth medium for M. pneumoniae and some other mycoplasmal species, the primary isolation medium for M. pneumoniae, and the metabolism-inhibition test medium for diagnosis of M. pneumoniae infection, egg yolk extract may be an excellent substitute for horse serum. The particular superiority of egg yolk extract to horse serum is that egg yolk extract, unlike horse serum, did not show any inhibitory effect on the growth of M. pneumoniae.

Utility of egg yolk medium for cultivation of Mycoplasma pneumoniae

Chicken egg yolk broth medium containing 10% (vol/vol) phosphate-buffered saline extract of egg yolk instead of horse serum showed better growth-promoting activity for Mycoplasma pneumoniae than did Chanock medium and was effective in promoting the growth of small numbers of M. pneumoniae. Moreover, the phosphate-buffered saline extract of egg yolk proved superior to horse serum in the following respects: (i) it was consistent in growth-promoting activity for M. pneumoniae among different batches; (ii) it could be preserved at 4 degrees C for at least 2 years; (iii) it is inexpensive and easy to obtain; and (iv) it contains large amounts of lipoproteins, cholesterol, and phospholipids.

Comparison of undefined medium and its dialyzable fraction for growth of Mycoplasma

In examining the medium used in cultivation of Mycoplasma for deoxyribonucleic acid isolation, it was found that an aggregate was present which sedimented with the organisms and which was ethyl alcohol-precipitated during deoxyribonucleic acid purification. To eliminate the contaminating material, a method was devised to obtain only the dialyzable constituents of the medium. This report describes the preparation of a dialysate of soy peptone-yeast extract. The medium, obtained by immersion of the encased dehydrated ingredients in sodium chloride solution for 5.5 hr at approximately 80 C, has been employed as the basal medium for cultivation of a number of Mycoplasma species. Comparative growth curves of two saprophytic strains and two parasitic species indicated that multiplication in dialysate, with suitable supplement, followed the pattern typical of the common eubacteria. Thus, by elimination of the sediment which occurred in nondialyzed medium, Mycoplasma could be concentrated without concomitant accumulation of contaminating macromolecules.