Characterization of an extracellular aflatoxin B1 degrading enzyme from a Pseudomonas strain

Abstract:

[Background] Aflatoxin B1 (aflatoxin B1, AFB1) is a highly toxic and widespread mycotoxin. At present, there is no effective method to control its pollution. [Objective] To discover efficient AFB1 degrading bacteria and explore its degradation characteristics, enzymatic properties of an AFB1 degrading strain (HAI2) from mangrove sludge samples were analyzed. [Methods] Using the structural analogue of AFB1 as the sole carbon source, a highly efficient AFB1 degrading strain was screened out, then 16S rRNA gene sequencing technology was used to identify the strain species, and HPLC was used to analyze the strain’s degradation characteristics to AFB1. [Results] 16S rRNA gene sequence of HAI2 shares 99.85% homology with Pseudomonas putida (NR 113651.1). The main component of degradation AFB1 was extracellular protein. According to the analysis of enzymatic properties, the optimum pH value of HAI2-AFB1 degrading enzyme was 7.0 and the optimum temperature was 37 °C. Fe2+, Ca2+, and Zn2+ could inhibit the degradation rate of AFB1, and Cu2+ and Mn2+ could increase the degradation rate of AFB1. The degradation rate of 100 ng/mL AFB1 by HAI2 supernatant was 71.52% for 24 h. Besides, P. putida HAI2 could inhibit AFB1 synthesis in corn infected by Aspergillus flavus, and the content could be reduced by 63.46%. [Conclusion] P. putida HAI2 had a high ability to degrade AFB1, and its main degradation active substance was extracellular protein, with a large application prospect in the food and feed industry.