Abstract
Mycoplasmas require a sterol for growth. To meet this requirement, horse serum (HS) has been used most frequently in mycoplasma media. In this study, chicken egg yolk extract (EY) was tested as an HS substitute.
The tested strains were Mycoplasma salivarium ATCC 23064, Mycoplasma orate ATCC 15539 and Ureaplasma urealyticum ATCC 27816.
The growth-promoting (g. p.) ability of EY in liquid medium: EY medium (PPLO broth incorporatedwith 10% EY) and HS medium (mycoplasma or ureaplasma media consisting of PPLO broth, HS and yeast extract) were inoculated with tested strains, and viable counts (v. c.) were measuredperiodically. M. orale grew better in EY than HS medium. The maximum (m.) v. c. in EY mediumwere 10 to 100 times those in HS medium. The growth of M. salivarium in EY medium was nearlycomparable to that in HS medium, although m. v. c. in HS medium were approximately 10 timesthose in EY medium. Ureaplasma did not grow in EY medium.
The g. p. ability of EY in agar medium: The liquid medium was supplemented with 1% agarand plated. M. salivarium and M. orale produced almost the same number of colonies on EY and HS medium. But the size of the colonies was considerably smaller on EY than HS medium. U. urealyticum did not grow on EY medium, but grew well on the medium enriched with 10% yeastextract.
Based on the results, it was concluded that HS can be replaced by EY in mycoplasma mediafor cultivation of laboratory strains of M. salivarium and M. orate for some limited purposes, although EY is a little inferior to HS in g. p. ability.
