The Significance of Yeast Extract Composition on Metabolite Production in Penicillium
In the literature and in our own experience, significant variations occur in morphological characteristics and production of secondary metabolites by cultures grown on YES (2% yeast extract and 15% sucrose) agar, a substrate which is often used in screening for mycotoxins in moulds. In this investigation we have demonstrated a very significant influence of yeast extract brand (Difco, Sigma Y4000 and Y0325, Oxoid, Merck, Lab M and Gibco) on the production of mycotoxins in YES by some important Penicillia. Using a TLC screening method the variation in mycotoxin production due to the use of different brands of yeast extract ranged between detection in 5 days and none detected in 4 weeks. The difference in mycotoxin production was often accompanied by differences in several other characteristics like pH changes of the substrate, sporulation, colony diameter and reverse colour. We have been unable to find which components in the yeast extracts were responsible for the observed changes, but the addition of MgSO4 appeared to be a satisfactory compensation in most respects. So it is suggested that this compound in general is added to the YES formula, along with previously suggested compounds like ZnSO4 and CuSO4, thus making this substrate a very valuable and reliable tool in screening for production of secondary metabolites and in mould taxonomy. Further it is suggested to use pH registration monitoring in the cultures parallel to screening for secondary metabolites, since pH differences proved to be a useful indication of significant changes in the detected profiles.
KeywordsYeast Extract Secondary Metabolite Metabolite Production Colony Diameter Kojic Acid
Unable to display preview. Download preview PDF.
- Betina, V., ed. 1984. Mycotoxins: production, isolation, separation and purification. Amsterdam: Elsevier.Google Scholar
- Bridge, P.D., Hawksworth, Z., Kozakiewicz, Z., Onions, A.H.S., Paterson, R.R.M. and Sackin, M.J. 1985. An integrated approach to Penicillium systematics. In Advances in Penicillium and Aspergillus Systematics, eds. R.A. Samson and J.I. Pitt, pp. 281–309. New York and London: Plenum Press.Google Scholar
- Constantinescu, O. 1990. Standardisation of methods in Penicillium identification. In Modern Concepts in Penicillium and Aspergillus Classification, eds. R.A. Samson and J.I. Pitt, pp. 17–25 New York and London: Plenum Press.Google Scholar
- Filtenborg, O. and Frisvad, J.C. 1980. A simple screening method for toxinogenic moulds in pure culture. Lebensmittel Wissenschaft und Technologie 13: 128–130.Google Scholar
- Frisvad, J.C. and Filtenborg, O. 1989. Terverticillate Penicillia: Chemotaxonomy and mycotoxin production. Mycologia 81 (in press).Google Scholar
- Frisvad, J.C. Filtenborg, O. and Thrane, U. 1989. Analysis and screening for mycotoxins and other secondary metabolites in fungal cultures by thin-layer chromatography and high-performance liquid chromatography. Archives of Environmental Contamination and Toxicology 18: 331–335.PubMedCrossRefGoogle Scholar
- Krumphanzl, V., Sikyta, B. and Vanek, Z. eds. 1982. Overproduction of microbial products. London: Academic Press.Google Scholar
- Pitt, J.I. 1979. The genus Penicillium and its teleomorphic states Eupenicilium and Talaromyces. London: Academic Press.Google Scholar
- Samson, R.A. and Pitt, J.I., eds. 1985. Advances in Penicillium and Aspergillus Systematics. New York en London: Plenum Press.Google Scholar
- Turner, W.B. 1971. Fungal metabolites. London: Academic Press.Google Scholar