The effect of ionophores on growth and glycosyltransferase production of Streptococcus sanguis

Abstract Batch cultures of Streptococcus sanguis NCTC7865 were grown in complex medium in the presence and absence of the ionophores gramicidin, valinomycin and nigericin, to study their effects on growth and glycosyltransferase production. Growth of S. sanguis was markedly inhibited by nigericin or gramicidin, whereas valinomycin had no significant effect. The presence of ionophores caused only slight decreases in glucosyltransferase activity. Fructosyltransferase activity was however reduced by at least 90%. The results indicate that ΔpH rather than ΔΨ is essential for maintaining normal growth in S. sanguis . However, both ΔpH and ΔΨ are necessary for fructosyltransferase synthesis and secretion, but are not apparently involved in the synthesis and secretion of glucosyltransferase.