, Volume 107, Issue 2–3, pp 127–130 | Cite as

Metabolic precursor regulation of aflatoxin formation in toxigenic and non-toxigenic strains ofAspergillus flavus

  • L. S. Lee


Non-aflatoxin-producing isolates ofAspergillus flavus from nature and isolates ofA. flavus that had lost their toxigenic trait following laboratory transfer were compared biochemically. After the addition of aflatoxin B1 precursors sterigmatocystin or O-methylsterigmatocystin to whole cell cultures, the non-toxin producing isolates from nature remained non-toxigenic while toxigenicity was restored in the nontoxigenic laboratory strains. Results imply a lack of enzymes needed for biochemical conversions of precursors to aflatoxin B1 in natural non-producers and suppression of these enzymes in the nonproducing laboratory strains.

Key words

aflatoxin Aspergillus flavus non-toxigenic O-methylsterigmetocystin sterigmetocystin nontoxigenic 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Adye J, Mateles RI. Incorporation of labelled compounds into aflatoxins. Biochem Biophs Acta 1964; 86: 418–20.Google Scholar
  2. 2.
    Bennett JW, Christensen SB. New perspectives on aflatoxin biosynthesis. Adv Appl Microbiol 1983; 29: 53–92.Google Scholar
  3. 3.
    Dutton MF. Enzymes and aflatoxin biosynthesis. Microbiol Rev. 1988; 52: 274–95.Google Scholar
  4. 4.
    Bennett JW, Lee LS, Shos SM, Boudreaux GH. Identification of averantin as an aflatoxin B1 precursor: Placement in the biosynthetic pathway. Appl Environ Microbiol 1980; 39: 835–9.Google Scholar
  5. 5.
    Bhatnagar D, McCormick SP, Lee LS, Hill RA. Identification of O-methylsterigmatocystin as an aflatoxin B1 and G1 precursor inAspergillus parasiticus. Appl Environ Microbiol 1987; 53: 1028–33.Google Scholar
  6. 6.
    Cleveland TE, Lax AR, Lee LS, Bhatnagar D. Appearance of enzyme activities catalyzing conversion of sterigmatocystin to aflatoxin B1 in late-growth-phaseAspergillus parasiticus cultures. Appl Environ Microbiol 1987; 53: 1711–13.Google Scholar
  7. 7.
    Dorner JW, Cole RJ, Diener UL. The relationship ofAspergillus flavus andAspergillus parasiticus with reference to production of aflatoxins and cyclopiazonic acid. Mycopathologia 1984; 87: 13–15.Google Scholar
  8. 8.
    Hesseltine CW, Shotwell OL, Smith M, Ellis JJ, Vandergraft E, Shannon G. Production of various aflatoxins by strains of theAspergillus flavus series. In: Herzberg M, ed. Proceedings of the First U.S.-Japan Conference on Toxic Microorganisms, UJNR Joint Panels on Toxic Micro-organisms and the US Dept. of the Interior, U.S. Govt. Printing Office Washington DC, 1970: 202–10.Google Scholar
  9. 9.
    Hsieh DPH, Lin MT, Yao RC. Conversion of sterigmatocystin to aflatoxin B1 byAspergillus parasiticus. Biochem Biophys Res Commun 1973; 52: 992–97.Google Scholar
  10. 10.
    Hsieh DPH, Lin MT, Yao RC, Singh R. Biogenesis of aflatoxins: Conversion of norsolorinic acid and other hypothetical intermediates into aflatoxin B1 byAspergillus parasiticus. J Agric Chem 1976; 24: 1171–74.Google Scholar
  11. 11.
    Lax AR, Cleveland TE, Bhatnagar D, Lee LS. Enzymatic conversion of sterigmatocystin to aflatoxin B1 through O-methylsterigmatocystin. Plant Physiol 1986; 80: S-19.Google Scholar
  12. 12.
    Lee LS, Bennett JW, Cucullu AF, Ory RL. Biosynthesis of Aflatoxin B1. Conversion of versicolorin A to aflatoxin B1 byAspergillus parasiticus. J Agric Food Chem 1976; 24: 1167–70.Google Scholar
  13. 13.
    Lee LS, Lax AR, Mellon JE, Klich MA. Stability for the character for aflatoxin production byAspergillus flavus obtained from Arizona cotton. J Am Oil Chem Soc 1986; 4: 694A.Google Scholar
  14. 14.
    Lin MT, Hsieh DPH, Yao RC, Donkersloot JA. Conversion of averufin into aflatoxins byAspergillus parasiticus. Biochemistry 1973; 12: 5167–71.Google Scholar
  15. 15.
    McCormick SP, Bhatnagar D, Lee LS. Averufanin is an aflatoxin precursor between averantin and averufm in the biosynthetic pathway. Appl Environ Microbiol 1987; 53: 14–16.Google Scholar
  16. 16.
    Shroeder HW, Cole RJ, Grigsby RD, Hein Jr. H. Inhibition of aflatoxin production and tentative identification of an aflatoxin intermediate ‘Versiconal acetate’ from treatment with dichlorvus. Appl Microbiol 1974; 27: 394–9.Google Scholar

Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • L. S. Lee
    • 1
  1. 1.Southern Regional Research CenterNew OrleansUSA

Personalised recommendations