Aflatoxin-Exposure of Vibrio gazogenes as a Novel System for the Generation of Aflatoxin Synthesis Inhibitors
Aflatoxin-Exposure of Vibrio gazogenes as a Novel System for the Generation of Aflatoxin Synthesis Inhibitors
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DOI：
10.3389/fmicb.2016.00814
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发表时间：
2016-06-03
影响因子：
5.2
通讯作者：
Chanda, Anindya
中科院分区：
文献类型：
--
作者：
Gummadidala, Phani M.;Chen, Yung Pin;Chanda, Anindya
黄曲霉毒素是一种真菌毒素和次级代谢物，是已知最强的肝脏致癌物，污染几种重要作物，对公众健康和经济构成重大威胁。迄今为止报道的可用方法不足以消除这种威胁，因此提供了探索防止黄曲霉毒素在环境中积累的新方法的理由。许多陆生植物和微生物，共享生态位，并遇到黄曲霉毒素生产者有能力合成化合物，抑制黄曲霉毒素的合成。然而，报告的天然黄曲霉毒素抑制剂的海洋生态系统组成部分，不共享生态位的黄曲霉毒素生产者是罕见的。在这里，我们表明，一个非致病性的海洋细菌，产气弧菌，当暴露于低无毒剂量的黄曲霉毒素B-1，表现出其代谢产物的转变，并合成代谢产物馏分，抑制黄曲霉毒素的合成，而不影响菌丝生长的模型黄曲霉毒素生产者，寄生曲霉。该馏分中主要代谢产物的分子量也不同于已知的灵菌红素，后者是由该弧菌合成的已知抗真菌次级代谢产物。使用RT-PCR的基因表达分析表明，该代谢产物部分通过下调生长阶段早期、中期和晚期黄曲霉毒素基因、黄曲霉毒素途径调节剂aflR和次级代谢的一个全局调节剂laeA的表达来抑制黄曲霉毒素合成。我们的研究建立了一个新的系统产生的黄曲霉毒素合成抑制剂，并强调了潜在的未开发的弧菌的沉默基因组产生新的真菌次生代谢调节剂。
Aflatoxin is a mycotoxin and a secondary metabolite, and the most potent known liver carcinogen that contaminates several important crops, and represents a significant threat to public health and the economy. Available approaches reported thus far have been insufficient to eliminate this threat, and therefore provide the rational to explore novel methods for preventing aflatoxin accumulation in the environment. Many terrestrial plants and microbes that share ecological niches and encounter the aflatoxin producers have the ability to synthesize compounds that inhibit aflatoxin synthesis. However, reports of natural aflatoxin inhibitors from marine ecosystem components that do not share ecological niches with the aflatoxin producers are rare. Here, we show that a non-pathogenic marine bacterium, Vibrio gazogenes, when exposed to low non-toxic doses of aflatoxin B-1, demonstrates a shift in its metabolic output and synthesizes a metabolite fraction that inhibits aflatoxin synthesis without affecting hyphal growth in the model aflatoxin producer, Aspergillus parasitic us. The molecular mass of the predominant metabolite in this fraction was also different from the known prodigiosins, which are the known antifungal secondary metabolites synthesized by this Vibrio. Gene expression analyses using RT-PCR demonstrate that this metabolite fraction inhibits aflatoxin synthesis by down-regulating the expression of early-, middle-, and late growth stage aflatoxin genes, the aflatoxin pathway regulator, aflR and one global regulator of secondary metabolism, laeA. Our study establishes a novel system for generation of aflatoxin synthesis inhibitors, and emphasizes the potential of the under explored Vibrio's silent genome for generating new modulators of fungal secondary metabolism.