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Correlation between catalase activity and aflatoxin synthesis in Aspergillus flavus

The aim of this study was to determine whether there is a correlation between catalase activity of Aspergillus flavus, grown on substrates which either induce or inhibit the synthesis of aflatoxins. The work used GMS and PMS liquid media which only differ in glucose (GMS) and peptone (PMS) content. Following cultivation of mold, extraction, and immunoaffinity clean-up, aflatoxin levels were determined using HPLC. Based on the results, glucose has a higher degree of conversion to mold biomass than peptone. A total of 23 ppb aflatoxin was detected in the PMS medium, while the GMS had a significantly higher amount of up to 362 ppb. Pepton is a source of nitrogen which made the PMS medium more suitable for protein synthesis. Catalase activity was lower in the glucose-based GMS medium, as expected. The enzyme activity and the amount of aflatoxins were inversely proportional regardless of medium: GMS r = -0.91 (p = 0.03) ; PMS r = -0.94 (p = 0.02). Apparently, the decline of catalase activity may have contributed to cellular oxidative stress prompting molds to aflatoxin synthesis.

catalase; aflatoxins; Aspergillus flavus; oxidative stress; HPLC

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