Regulation of aflatoxin biosynthesis. III. Comparative study of adenine nucleotide pool in aflatoxigenic and non-aflatoxigenic strains.

The adenine nucleotide pools were studied in toxigenic (NRRL 3240) and non-toxigenic (NRRL 3537) strains of Aspergillus flavus group in relation to aflatoxin biosynthesis. The levels of ADP and AMP were comparatively low in the non-toxigenic strain throughout the growth period. In the toxigenic strain the levels of ADP and AMP increased significantly during the stationary phase. The ATP content of the toxigencic strain had higher ATP levels during the stationary phase compared to the toxigenic strain. The inorganic phosphate levels of the non-aflatoxigenic strain were higher when compared with the aflatoxigenic strain. High levels of inorganic phosphate have been reported to be inhibitory for secondary biosynthesis including aflatoxins. The energy charge values of the non-toxigenic strain, compared to the toxigenic strain, were lower during exponential phase but higher during stationary phase. The observed changes have been correlated with aflatoxin biosynthesis.