Degradation Mechanism of Aflatoxin M₁ by Recombinant Catalase from <i>Bacillus pumilus</i>E-1-1-1: Food Applications in Milk and Beer

Abstract

A bacteria capable of degrading aflatoxin M1 (AFM1) was isolated from African elephant manure. It was identified as Bacillus pumilus by 16s rDNA sequencing and named B. pumilusE-1-1-1. Compared with physical and chemical methods, biological methods have attracted much attention due to their advantages, such as thorough detoxification, high specificity, and environmental friendliness. This work aimed to study the effects of a recombinant catalase (rCAT) from B. pumilusE-1-1-1 on the degradation of AFM1 in pattern solution. The degradation mechanism was further explored and applied to milk and beer. Kinetic Momentum and Virtual Machine Maximum values for rCAT toward AFM1 were 4.1 μg/mL and 2.5 μg/mL/min, respectively. The rCAT-mediated AFM1 degradation product was identified as C15H14O3. Molecular docking simulations suggested that hydrogen and pi bonds played major roles in the steadiness of AFM1–rCAT. In other work, compared with identical density of AFM1, survival rates of Hep-G2 cells incubated with catalase-produced AFM1 degradation products increased by about 3 times. In addition, degradation rates in lager beer and milk were 31.3% and 47.2%, respectively. Therefore, CAT may be a prospective substitute to decrease AFM1 contamination in pattern solution, milk, and beer, thereby minimizing its influence on human health.

Keywords

• catalase
• biological degradation
• catalase-mediator system
• degradation products
• hepatotoxicity