Abstract
Aspergillus oryzae strains are used extensively in the food industry. Some of these strains excrete alpha-cyclopiazonic acid (CPA), a mycotoxin which may provoke toxicoses in rats. Physicochemical methods may reveal the presence of this toxin, but they are inadequate to screen CPA-nonproducing (CPA-) strains. CPA production is revealed by either bacterial growth inhibition or alkalinization of the culture medium. This first biological property was used to devise a time-saving screening method to isolate mutants affected in their ability to produce CPA. The second method was used as a further test. After N-methyl-N'-nitro-N-nitrosoguanidine treatment, we isolated CPA- mutants from CPA producer strains (CPA+) and CPA+ mutants from CPA- strains. The mutants unable to produce CPA may be used in the food industry to reduce or eliminate the risk of intoxication in humans. Heterokaryon formation between different mutant strains was carried out to evaluate the risks of obtaining CPA from a mixture of mutants modified in their ability to synthesize this toxin. Pairings between two CPA+ strains always gave rise to CPA+ heterokaryons. Pairings between CPA+ and CPA- strains led, most often, to CPA+ heterokaryons. This could be directly correlated to the more frequent genotype (CPA+) in the heterokaryon. CPA hypoproducer and hyperproducer heterokaryons were obtained. Pairings between CPA- strains always gave rise to CPA- heterokaryons. These results suggest that the risks of producing this toxin from two CPA- individuals are not high.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Boutibonnes P. Mise en évidence de l'activité antibactérienne de quelques mycotoxines par utilisation de Bacillus thuringiensis (Berliner). Mycopathologia. 1979 Mar 30;67(1):45–50. doi: 10.1007/BF00436240. [DOI] [PubMed] [Google Scholar]
- Harris S. A., Fisher L. V., Folkers K. The synthesis of tenuazonic and congeneric tetramie acids. J Med Chem. 1965 Jul;8(4):478–482. doi: 10.1021/jm00328a014. [DOI] [PubMed] [Google Scholar]
- Holzapfel C. W. The isolation and structure of cyclopiazonic acid, a toxic metabolite of Penicillium cyclopium Westling. Tetrahedron. 1968 Mar;24(5):2101–2119. doi: 10.1016/0040-4020(68)88113-x. [DOI] [PubMed] [Google Scholar]
- Lafont P., Lafont J., Payen J., Chany E., Bertin G., Frayssinet C. Toxin production by 50 strains of Penicillium used in the cheese industry. Food Cosmet Toxicol. 1976 Apr;14(2):137–139. doi: 10.1016/s0015-6264(76)80258-1. [DOI] [PubMed] [Google Scholar]
- Le Bars J. Cyclopiazonic acid production by Penicillium camemberti Thom and natural occurrence of this mycotoxin in cheese. Appl Environ Microbiol. 1979 Dec;38(6):1052–1055. doi: 10.1128/aem.38.6.1052-1055.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Orth R. Mycotoxins of Aspergillus oryzae strains for use in the food industry as starters and enzyme producing molds. Ann Nutr Aliment. 1977;31(4-6):617–624. [PubMed] [Google Scholar]
- Purchase I. F. The acute toxicity of the mycotoxin cyclopiazonic acid to rats. Toxicol Appl Pharmacol. 1971 Jan;18(1):114–123. doi: 10.1016/0041-008x(71)90320-6. [DOI] [PubMed] [Google Scholar]
- Sorenson W. G., Tucker J. D., Simpson J. P. Mutagenicity of tetramic mycotoxin cyclopiazonic acid. Appl Environ Microbiol. 1984 Jun;47(6):1355–1357. doi: 10.1128/aem.47.6.1355-1357.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thorbek L., Eplov P. The formation, general characteristics and production of alpha-amylase in heterocaryons and diploids of Aspergillus oryzae. J Appl Bacteriol. 1974 Dec;37(4):549–557. doi: 10.1111/j.1365-2672.1974.tb00480.x. [DOI] [PubMed] [Google Scholar]