玉米赤霉烯酮脱毒菌PA26-7的分离鉴定及其应用效果评价

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

摘要:

【背景】玉米赤霉烯酮(zearalenone, ZEN)是广泛污染粮谷类作物的一种雌激素类真菌毒素，不仅给农业经济带来巨大损失，还能通过食物链对人和动物健康造成危害。【目的】从微生态制剂中筛选获得能够高效降解玉米赤霉烯酮的菌株，优化其脱毒条件，测定其在饲料中的实际脱毒效果及对饲料中植酸、维生素含量变化的影响。【方法】从微生态制剂中分离出玉米赤霉烯酮降解菌，通过细胞计数试剂盒-8 (cell counting kit-8, CCK-8)测定菌株降解玉米赤霉烯酮产物的细胞毒性和雌激素活性，通过高效液相色谱法测定分离株在培养基和饲料中的解毒效果，以及分离株在霉变的豆粕、麸皮和成品饲料中固态发酵前后维生素的含量变化，通过三氯化铁比色法测定饲料脱毒前后植酸的含量变化。【结果】从微生态制剂中筛选出一株通过分泌胞外酶高效降解玉米赤霉烯酮的贝莱斯芽孢杆菌(Bacillus velezensis) PA26-7，该菌株在培养基起始pH 4.0-8.0、培养温度25-60 ℃条件下均可降解玉米赤霉烯酮，产物的细胞毒性和雌激素活性均较ZEN弱。PA26-7经固态发酵72 h后，饲料原料(豆粕和麸皮)及霉变的成品鸡饲料中玉米赤霉烯酮含量下降66.2%-96.8%，植酸含量下降8.40%-32.26%，维生素B₂、维生素C和叶酸的含量显著提高。【结论】B. velezensis PA26-7可作为饲料中玉米赤霉烯酮的生物脱毒菌株，其固态发酵有效清除了饲料中的植酸，并产生了多种维生素，有利于改善饲料的营养结构。

关键词:玉米赤霉烯酮;贝莱斯芽孢杆菌;饲料脱毒;植酸;维生素

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.

Key words:zearalenone;Bacillus velezensis;feed detoxification;phytic acid;vitamin