本文研究了吲哚对黄曲霉的生长以及产毒的抑制作用。通过96孔板微量法发现吲哚能够抑制黄曲霉的生长，其最小抑制浓度（MIC）为100 μg/mL；进而采用差量法测定了吲哚对黄曲霉菌丝生长量的抑制作用，结果表明200 μg/mL的吲哚处理可以完全抑制黄曲霉的菌丝生长。此外，通过高效液相色谱分析发现吲哚浓度达到50 μg/mL时，尽管对菌丝生长量没有明显影响，但是可以有效地抑制黄曲霉毒素B1的产生。这些结果说明吲哚抑制毒素产生并不是通过抑制生长来实现的。为了进一步了解吲哚对毒素产生的抑制机制，本研究通过RT-PCR分析了吲哚对黄曲霉产毒相关基因表达的影响。结果显示吲哚对产毒调控基因aflR的影响与其对毒素的作用趋势相同，同时吲哚还能够下调其他一些产毒相关基因aflK和alfD的表达。我们的研究结果表明吲哚具有很高的开发价值应用于粮食和饲料中黄曲霉毒素污染的控制。

The inhibitory effects of indole on the mycelial growth and aflatoxin B1 production of Aspergillus flavus were investigated in this study. It was found that indole could efficiently inhibit the growth of A. flavus in a 96-well plate with the minimum inhibitory concentration (MIC) value of 100 μg/mL. Furthermore, the difference method was used to determine the inhibitory effects of indole on the mycelial weight of A. flavus. The results showed that 200 μg/mL indole could lead to the complete arrest of A. flavus mycelial growth. In addition, high performance liquid chromatography (HPLC) analysis showed that when the indole concentration was 50 μg/mL, the production of aflatoxin B1 was effectively inhibited whereas no significant impacts were observed on the mycelial growth of A. flavus. These results indicate that the inhibition of aflatoxin B1 production by indole is not achieved by inhibiting the mycelial growth of A. flavus. To further understand the mechanism underlying the inhibition of aflatoxin B1 production, reverse transcription polymerase chain reaction (RT-PCR) was performed to analyze the effects of indole on the expression of genes relevant to aflatoxin production. The results showed that indole exerted the same impacts on the expression of aflR- the regulatory gene in aflatoxin biosynthesis- as on aflatoxin B1 production. Additionally, indole could also downregulate the expression of aflD and aflK that are related to aflatoxin production. In summary, our results indicate that indole can be a potential candidate for application in the control of A. flavus contamination in food and animal feed.

国家自然科学基金资助项目（31101231）；河南省高校科技创新团队项目（13IRTSTHN006）