Prevalence of Aflatoxin M1 and Molecular Studies on Some Food Born Fungi Isolated from Milk and Dairy Products

Fungal contamination of milk and dairy products is the main cause of spoilage of these products and mycotoxicosis in humans. The aim of this study was to investigate the fungal contamination of milk and some dairy products. One hundred and twenty samples of milk and dairy products (20 of each processed cheese, Talaga cheese, powdered milk, UHT milk, pasteurized milk and raw milk) were collected from different markets at Giza Governorate, Egypt and then submitted for mycological, molecular examination and detection of Aflatoxin M1 residues(AFM1 ). The mycological examination revealed that the fungal contamination was not detected in Ultra high temperature (UHT) milk samples, whereas yeast contamination was detected only in Talaga cheese and raw milk with incidence rate of 50 % and 80%, respectively. In addition, the prevalence of moulds in processed cheese, Talaga cheese, powdered milk, pasteurized milk and raw milk was 90%, 30%, 35%, 30% and 80% respectively. Moreover, AFM1 residues were detected in Talaga cheese, powdered milk, UHT milk, pasteurized milk and raw milk with a prevalence of 20%,15%, 10%,20% and 15%, respectively. In this analysis, we have optimized the conditions for the use of real-time PCR (RT-PCR) together with propidium monoazide (PMA), (q PCR-PMA) for discrimination between the live and dead fungal cells in the examined samples. Nine samples of milk and dairy products, which were negative upon culturing, were subjected to ITS SYBR green RT- PCR, with the results showing that six out of the nine tested samples were found to be positive. After words, these six samples were subjected to propidium monoazide (PMA) treatment prior to RT-PCR to demonstrate the viability of the fungal cells. As a result, all of the six positive samples in RT-PCR were positive after PMA treatment, indicating that all positive RT-PCR samples contained viable but non-culturable fungal cells. In conclusion, Propidium monoazide (PMA) treatment accompanied with RT- PCR is a rapid and reliable method for molecular identification of fungal contamination in milk and milk products.