Dairy Industry Association of Australia

Microbial interactions are of importance for the establishment and growth of cheese ripening cultures. An interesting aspect of microbial interactions is cell-cell communication, often referred to as quorum sensing; the process in which micro-organisms communicate with
signalling molecules and co-ordinate gene expression in a cell density dependent manner. Little is known about quorum sensing in foods. However, as quorum sensing is expected to be a general phenomenon in micro-organisms, it is likely to be of importance for micro-organisms in foods. An example of a food product where quorum sensing could be of importance is surface ripened cheeses. The present review focuses on our findings on quorum sensing systems in cheese ripening cultures. The main focus is on the group of bacterial non-species-specific signalling molecules referred to as autoinducer-2 (AI-2) in smear bacteria as well as alcohol-based and ammonia signalling in the dairy-relevant yeast Debaryomyces hansenii. Furthermore, the influence of cheese matrices on quorum sensing systems is briefly mentioned. Finally, we discuss how knowledge on quorum sensing systems in cheese ripening cultures may be used for optimisation of the ripening processes.