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

Abstract

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.

Keywords: Aflatoxin B(1); Aspergillus flavus; Biosensor; Catalase; Electrochemical method.