中文摘要：种子受聚酮霉菌毒素如曲霉产生的杂色曲霉素（ST）污染是一个全球性问题。构巢曲霉中ST的生物合成途径已经非常明了，但碳源调控方面仍然是谜。乳糖尤其如此，因为某些产ST的变异株仍能利用乳糖合成ST，但用其它碳源则不行。在此，动力学数据显示利用D-葡萄糖，仅在培养基中的糖耗尽之后合成ST；而利用乳糖，则发生在大部分的碳源仍然可用时。利用乳糖产生的ST生物量明显高于利用D-葡萄糖的，说明ST形成可能由碳代谢的调节机制介导，或低比生长率时利用乳糖引起。这些推测通过有限D-葡萄糖恒化连续发酵进行验证。结果发现高增长率时无ST形成，而低增长率生成了0.4mg/L的ST。通过CreA突变株也得到了类似结果。由此得出如下结论：低比生长率可能是构巢曲霉利用乳糖生长中期形成ST的主要原因，以及碳利用率可能在生物合成时起着普通的调节作用。
外文摘要：Seed contamination with polyketide mycotoxins such as sterigmatocystin (ST) produced by Aspergilli is a worldwide issue. The ST biosynthetic pathway is well-characterized in A. nidulans, but regulatory aspects related to the carbon source are still enigmatic. This is particularly true for lactose, inasmuch as some ST production mutant strains still synthesize ST on lactose but not on other carbon substrates. Here, kinetic data revealed that on d-glucose, ST forms only after the sugar is depleted from the medium, while on lactose, ST appears when most of the carbon source is still available. Biomass-specified ST production on lactose was significantly higher than on d-glucose, suggesting that ST formation may either be mediated by a carbon catabolite regulatory mechanism, or induced by low specific growth rates attainable on lactose. These hypotheses were tested by d-glucose limited chemostat-type continuous fermentations. No ST formed at a high growth rate, while a low growth rate led to the formation of 0.4 mg·L−1 ST. Similar results were obtained with a CreA mutant strain. We concluded that low specific growth rates may be the primary cause of mid-growth ST formation on lactose in A. nidulans, and that carbon utilization rates likely play a general regulatory role during biosynthesis.
外文关键词：Aspergillus nidulans；sterigmatocystin；lactose；D-glucose；CreA；growth rate
作者：Nemeth, Z；Molnar, AP；Fejes, B；Novak, L；Karaffa, L；Keller, NP；Fekete, E
作者单位：Univ Debrecen
期刊名称：TOXINS
期刊影响因子：3.571
出版年份：2016
出版刊次：12
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