Interactions among thermophilic lactobacilli during growth in cheese whey

The starters used in the Parmesan cheese technology are whey‐cultured, mixed strain cultures of thermophilic rod lactic acid bacteria. In mixed strain cultures, interactions among different strains can result in both stimulatory or inhibitory effects on microbial growth rate and metabolic activity. These effects, studied by the use of conductance, were observed for individual strains of thermophilic lactobacilli, which were grown in whey and in the presence of cell‐free supernatant fluids from whey cultures of other strains. The importance of whey as a growth medium on the microbial composition of the whey cultures is discussed.