This study investigates the growth dynamics of Lactobacillus delbrueckii, a thermophilic lactic acid species used in the manufacture of numerous cheese varieties. Dynamics were studied during the moulding of Swiss-type cheeses manufactured from clean raw milk inoculated with different thermophilic starter species. 24 cheeses – 18 different combinations of starters and 6 replicates – were manufactured in similar and controlled conditions. The cheeses were inoculated with one strain of Streptococcus thermophilus – added at a low or a high level, Lactobacillus helveticus – strain 1, 2 or not, and Lactobacillus delbrueckii – strain 1, 2 or not. The strains 1 and 2 differed by their acidifying and proteolytic potentials evaluated in milk (high for both strains 1). The results showed a great variability of L. delbrueckii growth dynamics during cheese-making. We were able to relate statistically the growth dynamics of L. delbrueckii with some variables linked to the growth and metabolism of the other thermophilic bacteria. We also highlighted that different growth dynamics of L. delbrueckii generated different characteristics in the 1-day-old and ripened cheeses. Finally, we observed that the acidifying activity of the strain L. delbrueckii 2 in cheese was not predictable according to its potential evaluated in milk. During the moulding of Swiss-type cheeses, the growth dynamics of L. delbrueckii were influenced by the other thermophilic bacteria, which led to think that some interactions took place between some species of thermophilic lactic acid bacteria. These interactions and resulting L. delbrueckii growth dynamics have been found determinant for the characteristics of the ripened cheeses. Interactions between thermophilic bacteria have been pointed out. Like L. delbrueckii, growth dynamics of other thermophilic lactic acid bacteria could generate variability in ripened cheese, so these bacteria could be used as a mean to maintain diversity within Swiss-type cheeses.