Electrochemical analysis of specific catalase activity during development of Aspergillus flavus and its correlation with aflatoxin B1 production.

Aflatoxin B1 (AFB1) contamination causes huge economic losses. To explore the correlation between catalase (CAT) and AFB1 production during fungal development, we fabricated an electrochemical CAT-activity sensor by measuring residual H2O2 after enzymatic degradation. The sensor made by palladium nanoparticles/carbonized bacterial cellulose nanocomposites exhibits a linear range over 0.5-3.5 U/mL and a detection limit of 0.434 U/mL. Both dry weight and CAT activity of mycelia continuously increase. But, the latter shows a greater increase than the former after three days. Specific CAT activity in crude enzyme extract of A. flavus was quantified. It maintains at ~25.00 U/mg for 3 days and enhances to 28.91 and 45.30 U/mg, respectively, on days 4 and 5. AFB1 production follows the same trend. On days 4 and 5, AFB1 concentration reaches 201.35 and 767.9 ng/mL, respectively. The positive correlation between specific CAT activity and AFB1 production suggests that CAT is involved in AFB1 biosynthesis.