Abstract
Streptococcus thermophilus grows as chains of variable length which can be broken by processes such as freezing or freeze-drying. This makes survival rates difficult to establish by the agar plate method. Our studies showed that in the presence of cations (Mg2+, Li+, and Na+), these bacteria grew as shorter chains and their enumeration was more precise. A maximal length chain reduction was obtained with sodium concentrations over 80 HIM. Moreover, growth was strongly stimulated by the buffering effect of sodium salts such as acetate and hydrogen carbonate. Finally, this shortening effect of sodium occurred in 17 out of the 20 Streptococcus thermophilus strains tested.
