Calcium as a growth stimulant for Lactobacillus casei.

Extensive information has been accumulated concerning the organic nutrient requirements of lactic acid bacteria. Studies of the inorganic requirements of these organisms have been pursued less vigorously. Several investigations (Woolley, 1941; McLeod and Snell, 1947; Rogosa, 1944) have been undertaken to determine the essentiality of Mn++, Mg++, K+, Fe++, and PO-for Lactobacillus caswi, strain 7469. Chattaway, Happold, and Sanford (1943) reported that calcium is needed for maximum acid production by L. casei. It has been shown that L. case growth rate is enhanced by the presence of calcium (Eades, 1948). Meinke and Holland (1950) presented evidence that calcium is a stimulatory factor in the utilization of serine by Lactobacilus delbrueckii, strain 9595, and that L. casei growth is stimulated to some degree by calcium. We present evidence here that calcium is definitely a stimulatory factor for L. casei growth when that organism is cultured in a completely synthetic medium wherein the amino acids are supplied as purified entities instead of protein hydrolyzates.