334. A simple agar medium for the growth of lactic streptococci: the role of phosphate in the medium

Abstract

A cheap, easily prepared and relatively uniform agar medium, containing beef extract, lactose, peptone, yeast extract and phosphate, is described. It gives excellent results with lactic streptococci and a good growth with many other organisms.The role of phosphate and agar in the medium and the effect of filtration is discussed. It is suggested that the value of phosphate is due partly to its buffering effect and partly to its combination with some constituent of agar to form a substance which has a growth-promoting action on the lactic acid bacteria. This active substance is largely removed from the medium if filtration through paper pulp is practised.