Listeria monocytogenes is a Gram-positive, rod-shaped, food-borne bacterium, capable of causing the rare, but potentially fatal, disease listeriosis. L. monocytogenes can replicate at temperatures as low as 0°C, allowing it to survive in industrial and domestic refrigerators. L. monocytogenes is often found in soft cheeses, making many varieties of cheese unavailable to those who are immunosuppressed. Man-Cheester aims to introduce the agr quorum sensing system from L. monocytogenes into bacteria used in the cheese making process. On detection of AIP, a key quorum sensing molecule of L. monocytogenes, a colour change will occur, causing the cheese to turn purple and alerting the consumer to its contamination. Our concept could be further developed to include other sources of L. monocytogenes contamination, such as meats, vegetables or kitchen surfaces, to prevent as many cases of listeriosis as possible.