【摘要】 玉米赤霉烯酮（Zearalenone,ZEN）是镰刀菌属霉菌产生的一种霉菌毒素,常见于霉变的玉米、小麦等谷物中.研究发现,来源于粉红黏帚霉（Gliocladium roseum）的α/β水解酶ZHD101能够断裂ZEN的内酯键,破坏ZEN的毒性.本文利用食品安全级的马克斯克鲁维酵母（Kluyveromyces marxianus）重组分泌表达了ZHD101,发酵液上清中的表达产物具有水解ZEN的活性.利用UV和⁶⁰Co-γ联合诱变方法,提高了ZHD101在马克斯克鲁维酵母中的表达水平.高效液相色谱（HPLC）分析表明,重组菌株分泌表达的ZHD101酶蛋白既能水解标准品ZEN,又能在较温和的条件下水解发霉玉米样本中的ZEN,结果表明该重组菌株表达的玉米赤霉烯酮降解酶ZHD101,可应用于发霉玉米的脱毒处理.更多还原

【Abstract】 Zearalenone（ZEN）,a nonsteroid estrogenic mycotoxin,produced by numerous Fusarium species in several moldy cereals,causes hyperestrogenic syndrome and homeostasis disorder of livestock and poses genotoxicity and carcinogenicity in mammals and humans.ZHD101 is a lactone hydrolase from G.roseumthat could convert ZEN to a far less estrogenic product by hydrolyzing the lactone bond.In this study,we cloned and expressed the zhd101 gene in the GRAS（Generally Recognized as Safe）yeast K.marxianus for producing the ZHD101 hydrolase in vitro.To elevate the expression of heterologous zhd101 in the recombinant,the UV-⁶⁰Co-γirradiation mutagenesis was introduced and a mutant possessed tripled hydrolytic activity and high plasmid stability was isolated using a high-throughput screening system.The detoxification capability of the recombinant ZHD101 was further investigated using the moldy corn.HPLC analysis showed that ZHD101 lactonase from the FIM/N112-zhd101-M1 mutant could hydrolyze ZEN in the moldy corn samples completely after 12 hincubation at room temperature,suggesting that the recombinant K.marxianus strain could be applied to the detoxification of moldy cereals.更多还原