Screening and performance evaluation of a zearalenone-degrading bacterial isolate PA26-7

Abstract:

[Background] Zearalenone (ZEN) is non-steroidal estrogenic mycotoxin contaminating a variety of grain crops. ZEN can cause serious health problems in livestock and humans through the food chain, leading to great economic losses in the food industry and livestock farming. [Objective] To optimize the conditions for ZEN degradation and evaluate the degradation performance of a ZEN-degrading bacterial strain isolated from microecological preparations, and then study the influence of the strain on the content of phytic acid and vitamins in feed. [Methods] A ZEN-degrading bacterial strain was isolated from microecological preparations. The cytotoxicity and estrogenic activity of ZEN-degrading products were determined by Cell Counting Kit-8 (CCK-8). The phytic acid content in feed before and after detoxification was determined by ferric chloride colorimetry. HPLC was employed to determine the detoxification effect of the isolate in culture medium and feed and the vitamin content in feed before and after solid state fermentation. [Results] One bacterial isolate, Bacillus velezensis PA26-7, was obtained from microecological preparations, which efficiently degraded ZEN by secreting extracellular enzymes. PA26-7 degraded ZEN at the initial pH 4.0–8.0 and the incubation temperature of 25–60 ℃. The cytotoxicity and estrogenic activity of the degradation products were weaker than those of ZEN. The solid state fermentation with PA26-7 for 72 h decreased the content of ZEN by 66.2%–96.8%, decreased the content of phytic acid by 8.40%–32.26%, and increased the content of vitamin B2, vitamin C, and folic acid in the feed samples including soybean meal, bran, and moldy finished feed for chicken. [Conclusion] B. velezensis PA26-7 can be used as a biodetoxification strain for ZEN in feed. The solid-state fermentation with B. velezensis PA26-7 can effectively remove phytic acid in the feed and produce a variety of vitamins, which is conducive to improving the nutritional structure of feed.