Inorganic salts and the growth of spiroplasmas

Abstract

A chemically defined medium (CC-494M) was used to study the effect of inorganic salts on the growth of three spiroplasmas representing three distinct serogroups: Spiroplasma melliferum (AS 576), Spiroplasma floricola (23–6), and SR 3 spiroplasma. KH2PO4 or NaH2PO4∙H2O was required. KH2PO4 supported faster growth and higher yield for spiroplasmas than NaH2PO4∙H2O. The optimal concentration of KH2PO4 for S. melliferum, S. floricola, and SR 3 spiroplasma was 0.5, 0.5, and 0.25 mM, respectively, whereas that of NaH2PO4∙H2O was 0.5, 0.05, and 2.5 mM. When supplemented with NaH2PO4∙H2O, KCl promoted growth comparable with that obtained from KH2PO4-supplemented medium and RbCl supported limited growth, whereas NaCl, LiCl, CsCl, CaCl2, and MgSO4∙7H2O were inhibitory. Spiroplasma growth decreased as the concentration of LiCl and CsCl increased. At 200 mM LiCl totally inhibited the growth of S. melliferum and SR 3 spiroplasma, whereas limited growth was obtained for S. floricola. CsCl at 150 mM totally inhibited the growth of S. floricola, while limited growth was observed for S. melliferum and SR 3 spiroplasma. RbCl supported limited growth when supplemented with NaH2PO4∙H2O, whereas it was inhibitory when added in KH2PO4-supplemented medium. All the 10 potassium salts (KCH2COOH, KBr, K2CO3, KHSO4, KCl, KOH, Kl, KNO3, KH2PO4, and K2HPO4) at concentrations of 20 mM promoted growth when supplemented with NaH2PO4∙H2O.