Amino acid requirements for growth of Chlamydia pneumoniae in cell cultures: growth enhancement by lysine or methionine depletion.

Amino acid requirements for growth of two isolates of Chlamydia pneumoniae were studied and compared with those for one strain of Chlamydia trachomatis in a HeLa 229 cell culture. It was shown that among 13 amino acids in Eagle minimum essential medium, C. pneumoniae required all amino acids except lysine. A true requirement for arginine, isoleucine, leucine, threonine, and valine could not be determined because depletion of 100% of these amino acids caused cell detachment. Consequently, a requirement for these amino acids was based on 90% depletion. C. trachomatis biovar trachoma required all amino acids except threonine, which was indeterminable. Depletion of 100 and 90% of the lysine and 90 to 70% of the methionine was shown to enhance the growth of C. pneumoniae. This phenomenon was shown to be a property of C. pneumoniae because the effect of lysine and methionine reduction was also demonstrated in another human line, HL cells, and a mouse line, McCoy cells.