BACKGROUND Ustilago cynodontis ranks among the relatively unknown itaconate production organisms. In comparison to the well-known and established organisms like Aspergillus terreus and Ustilago maydis, genetic engineering and first optimizations for itaconate production were only recently developed for U. cynodontis, enabling metabolic and morphological engineering of this acid-tolerant organism for efficient itaconate production. These engineered strains were so far mostly characterized in small scale shaken cultures. RESULTS In pH-controlled fed-batch experiments an optimum pH of 3.6 could be determined for itaconate production in the morphology-engineered U. cynodontis Δfuz7. With U. cynodontis ∆fuz7r ∆cyp3r PetefmttA Pria1ria1, optimized for itaconate production through the deletion of an itaconate oxidase and overexpression of rate-limiting production steps, titers up to 82.9 ± 0.8 g L-1 were reached in a high-density pulsed fed-batch fermentation at this pH. The use of a constant glucose feed controlled by in-line glucose analysis increased the yield in the production phase to 0.61 gITA gGLC-1, which is 84% of the maximum theoretical pathway yield. Productivity could be improved to a maximum of 1.44 g L-1 h-1 and cell recycling was achieved by repeated-batch application. CONCLUSIONS Here, we characterize engineered U. cynodontis strains in controlled bioreactors and optimize the fermentation process for itaconate production. The results obtained are discussed in a biotechnological context and show the great potential of U. cynodontis as an itaconate producing host.

中文翻译：

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耐pH值的美人鱼（Ustilago cynodontis）的工艺设计，可有效生产衣康酸。

背景技术犬齿白头鹦鹉属于相对未知的衣康酸生产生物。与著名的和已建立的生物如土曲霉和乌斯季亚哥（Ustilago maydis）相比，伊卡藻的遗传工程和衣康酸生产的首次优化是最近才开发出来的，可对这种耐酸生物进行代谢和形态工程，以有效地生产衣康酸。迄今为止，这些工程菌株大多以小规模摇动培养为特征。结果在pH控制的分批投料实验中，可以确定形态工程化的美人鱼U. cynodontisΔfuz7中衣康酸酯生产的最佳pH为3.6。对于美人鱼∆fuz7r ∆cyp3r PetefmttA Pria1ria1，通过缺失衣康酸氧化酶和过量表达限速生产步骤对衣康酸生产进行了优化，在此pH下的高密度脉冲分批补料发酵中滴定度达到82.9±0.8 g L-1。通过在线葡萄糖分析控制的恒定葡萄糖进料的使用，将生产阶段的产量提高到0.61 gITA gGLC-1，这是最大理论途径产量的84％。生产率可以提高到最大1.44 g L-1 h-1，并且通过重复分批施用实现了细胞回收。结论在这里，我们表征了在受控的生物反应器中工程化的犬齿美人鱼菌株的特性，并优化了衣康酸酯生产的发酵过程。所获得的结果在生物技术背景下进行了讨论，并显示了犬齿单胞菌作为衣康酸酯生产宿主的巨大潜力。