Antagonism of lactic streptococci toward Staphylococcus aureus in associative milk cutures

The inhibition of growth of Staphylococcus aureus by lactic streptococci in associative cultures in milk was not due to hydrogen peroxide produced by the streptococci. Dialyzed whey from the milk culture of lactic streptococci was more inhibitory than dialyzed whey from milk acidified with lactic acid, indicating that material other than lactate was also involved. Analyses of cation and anion exchange fractions from the dialyzed whey showed that only the neutral fraction was inhibitory.