A new selective base medium for the rapid detection and enumeration of aflatoxin-producing Aspergillus flavus and Aspergillus parasiticus species is now available from Thermo Scientific. AFPA Base medium has been specially formulated to indicate the presence of these organisms in food samples, and demonstrate whether they are present in sufficient numbers to pose a significant risk to human health.
AFPA Base is a modification of Aspergillus Differential Medium1, and is based on the formulation devised by Pitt, Hocking and Glenn2. The product offers a number of advantages over other mycological media. It provides improved colour production on the reverse of the plate (due to the optimal concentration of a more soluble iron salt and the addition of yeast extract). Colonies of A. flavus and A. parasiticus develop an intense yellow/orange colouration on the reverse of the colonies, which is a differential characteristic for these species. The medium also improves the growth rate of A. flavus as its formulation achieves an optimal balance of peptone and yeast extract. In addition, use of a mixture of dichloran and chloramphenicol gives improved inhibition of bacteria and rapid growth of fungi.
Aspergillus often appears as a green mould when present on foods such as oilseeds, edible nuts and cereals, but the aflatoxins which may be produced are not visible to the naked eye. Aflatoxins may even be present when no outward indication of mould can be observed. Their acute toxic effects include cirrhosis of the liver, tumour induction and teratogenesis, and they can also act as immuno- suppressants leaving affected individuals susceptible to a wide range of diseases.
The isolation and enumeration of yeasts and moulds in food should ideally support the recovery of all viable propagules, restrict spreading moulds, inhibit bacterial growth and aid in the identification of the fungi under identification, says Alison Smith, Marketing Manager at Thermo Scientific, Our new AFPA Base medium comes very close to this ideal.
AFPA Base has been added to Thermo Scientifics extensive portfolio of mycological media under product code CM0731.