Dynamic flux balance modeling of S. cerevisiae and E. coli co-cultures for efficient consumption of glucose/xylose mixtures
Dynamic flux balance modeling of S. cerevisiae and E. coli co-cultures for efficient consumption of glucose/xylose mixtures
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DOI：
10.1007/s00253-011-3628-1
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发表时间：
2012-03-01
影响因子：
5
通讯作者：
Henson, Michael A.
中科院分区：
文献类型：
--
作者：
Hanly, Timothy J.;Urello, Morgan;Henson, Michael A.
目前利用木质纤维原料生产生物化学品的研究主要集中在利用复杂糖类混合物的单个微生物的鉴定和工程设计上。微生物联合体代表了另一种方法，有可能更好地利用个别物种的底物吸收和生化生产能力。在这项工作中，我们构建并实验验证了酿酒酵母和大肠杆菌共培养的动态流平衡模型，该模型旨在有效地有氧消耗葡萄糖/木糖混合物。每个微生物都是底物专家，野生型酿酒酵母只消耗葡萄糖，工程菌ZSC113只消耗木糖，以避免在单个微生物中常见的二次生长。在实验确定了最佳共培养批次生长的共同pH和温度之后，我们证明了为最佳生长条件开发的纯培养模型可以通过调整每个微生物的非生长相关的ATP维持来适应次优的共同生长条件。通过将纯培养模型预测与共培养实验数据进行比较，发现酿酒酵母产生的乙醇对大肠杆菌生长的抑制作用是共培养模型中唯一必要的交互作用，以生成准确的批次分布预测。通过预测不同糖混合物同时产生葡萄糖和木糖消耗的初始细胞浓度，证明了共培养模型的实用性。模型预测的成功实验验证表明，为单个微生物开发的稳态代谢重建可用于开发微生物群体的动态通量平衡模型，用于生产可再生化学品。
Current researches into the production of biochemicals from lignocellulosic feedstocks are focused on the identification and engineering of individual microbes that utilize complex sugar mixtures. Microbial consortia represent an alternative approach that has the potential to better exploit individual species capabilities for substrate uptake and biochemical production. In this work, we construct and experimentally validate a dynamic flux balance model of a Saccharomyces cerevisiae and Escherichia coli co-culture designed for efficient aerobic consumption of glucose/xylose mixtures. Each microbe is a substrate specialist, with wild-type S. cerevisiae consuming only glucose and engineered E. coli strain ZSC113 consuming only xylose, to avoid diauxic growth commonly observed in individual microbes. Following experimental identification of a common pH and temperature for optimal co-culture batch growth, we demonstrate that pure culture models developed for optimal growth conditions can be adapted to the suboptimal, common growth condition by adjustment of the non-growth associated ATP maintenance of each microbe. By comparing pure culture model predictions to co-culture experimental data, the inhibitory effect of ethanol produced by S. cerevisiae on E. coli growth was found to be the only interaction necessary to include in the co-culture model to generate accurate batch profile predictions. Co-culture model utility was demonstrated by predicting initial cell concentrations that yield simultaneous glucose and xylose exhaustion for different sugar mixtures. Successful experimental validation of the model predictions demonstrated that steady-state metabolic reconstructions developed for individual microbes can be adapted to develop dynamic flux balance models of microbial consortia for the production of renewable chemicals.