氧脂素对赭曲霉在大豆培养基质中合成赭曲霉毒素A的影响

Effect of oxylipins on ochratoxin A production by Aspergillus ochraceus in soybean culture medium

摘要:

【背景】赭曲霉毒素A (ochratoxin A，OTA)是曲霉属和青霉属等真菌的次级代谢产物，严重威胁农产品及食品安全，氧脂素羟基十八碳二烯酸(hydroxyoctadecaenoic acids，HODEs)被认为可能是曲霉属的群体感应信号分子，调节曲霉的生长发育和次级代谢物生成。【目的】主要研究HODEs对赭曲霉(Aspergillus ochraceus)菌株AS3.4412产生OTA的影响，检测孢子密度、培养基类别以及内、外源HODEs作用下OTA产量的不同变化。【方法】分别在PDB、黄豆和黑豆培养基中进行赭曲霉的培养，采用高效液相色谱-荧光检测法测定OTA含量，采用高效液相色谱-质谱法测定氧脂素含量，根据变化规律寻找赭曲霉群体密度、氧脂素、OTA三者间的关系。【结果】低密度赭曲霉培养物(103 spores/mL)中9(S)-HODE/13(S)-HODE及OTA产量高于高密度赭曲霉(106 spores/mL)；外源添加9(S)-HODE能促进OTA合成，13(S)-HODE可以抑制OTA合成；赭曲霉侵染抗氧化能力更高的黑豆产生更多的OTA。【结论】OTA的合成受到赭曲霉群体密度和氧脂素的影响，推测9(S)-HODE和13(S)-HODE是赭曲霉群体感应信号分子，并且二者在调节OTA合成中具有相反的作用。

Abstract:

[Background] Ochratoxin A (OTA) is a secondary metabolite of fungi such as Aspergillus spp. and Penicillium spp., which poses a serious threat to agricultural products and food safety. Oxygenated hydroxy octadecadienoic acid (HODEs) is considered the Quorum sensing signal molecules to regulate the growth and development of Aspergillus and the production of secondary metabolites. [Objective] This experiment mainly studied the effect of HODEs on OTA production of Aspergillus ochraceus AS3.4412, and detected different changes of spore density, medium type and OTA yield under the action of endogenous and exogenous HODEs. [Methods] The culture of AS3.4412 was carried out in PDB, soybean and black bean medium respectively. The content of OTA was determined by high performance liquid chromatography-fluorescence detection and the content of oxylipins was determined by high performance liquid chromatography-mass spectrometry. The relationship among population density of A. Ochraceus, Oxylipins and OTA was found according to the variation rule of the experimental results. [Results] The results showed that 9(S)-HODE/13(S)-HODE and OTA production in low density A. ochraceus (103 spores/mL) culture was higher than high density (106 spores/mL). Exogenous addition of 9(S)-HODE promoted OTA synthesis, and 13(S)-HODE inhibitd OTA synthesis. A. ochraceus infects black beans with higher antioxidant capacity and produces more OTA. [Conclusion] The results showed that population density and HODEs could affects the OTA production of A. ochraceus. It is speculated that 9(S)-HODE and 13(S)-HODE are quorum sensing signals of A. ochraceus, and they have the opposite effect in regulating OTA synthesis.