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首页> 外文期刊>Biotechnology Progress >Measurement and Analysis of Intracellular ATP Levels in Metabolically Engineered Zymomonas mobilis Fermenting Glucose and Xylose Mixtures
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Measurement and Analysis of Intracellular ATP Levels in Metabolically Engineered Zymomonas mobilis Fermenting Glucose and Xylose Mixtures

机译：代谢工程化运动发酵单胞菌发酵葡萄糖和木糖混合物的细胞内ATP水平的测量和分析

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摘要

Intracellular adenosine-5'-triphosphate (ATP) levels were measured in a metabolically engineered Zymomonas mobilis over the course of batch fermentations of glucose and xylose mixtures.Fermentations were conducted over a range of pH (5-6) in the presence of varying initial amounts of acetic acid (0-8 g/L) using a 10% (w/v) total sugar concentration (glucose only,xylose only,or 5% glucose/5% xylose mixture).Over the design space investigated,ethanol process yields varied between 56.6% and 92.3%+-1.3% of theoretical,depending upon the test conditions.The large variation in process yields reflects the strong effect pH plays in modulating the inhibitory effect of acetic acid on fermentation performance.A corresponding effect was observed on maximum cellular specific growth rates,with the rates varying between a low of 0.15 h~(-1) observed at pH 5 in the presence of 8 g/L acetic acid to a high of 0.32+-0.02 h~(-1) obtained at pH 5 or 6 when no acetic acid was initially present.While substantial differences were observed in intracellular specific ATP concentration profiles depending upon fermentation conditions,maximum intracellular ATP accumulation levels varied within a relatively narrow range (1.5 - 3.8 mg ATP/g dry cell mass).Xylose fermentations produced and accumulated ATP at much slower rates than mixed sugar fermentations (5% glucose,5% xylose),and the ATP production and accumulation rates in the mixed sugar fermentations were slightly slower than in glucose fermentations.Results demonstrate that higher levels of acetic acid delay the onset and influence the extent of intracellular ATP accumulation.ATP production and accumulation rates were most sensitive to acetic acid at lower values of pH.
机译：在葡萄糖和木糖混合物的分批发酵过程中，通过代谢工程化的运动发酵单胞菌（Zymomonas mobilis）测量了细胞内5'-三磷酸腺苷（ATP）的水平。使用总糖浓度为10％（w / v）的乙酸（0-8 g / L）（仅葡萄糖，仅木糖或5％葡萄糖/ 5％木糖混合物）。在研究的设计空间内，使用乙醇工艺取决于测试条件，收率在理论值的56.6％和92.3％+ -1.3％之间变化。过程收率的较大差异反映了pH在调节乙酸对发酵性能的抑制作用中发挥的强大作用。最大细胞比生长速率，在8 g / L乙酸存在下于pH 5时观察到的低值介于0.15 h〜（-1）到高至0.32 + -0.02 h〜（-1）之间当最初不存在乙酸时在pH 5或6下获得。根据发酵条件，在细胞内特定ATP浓度曲线中观察到差异，最大细胞内ATP积累水平在相对狭窄的范围内变化（1.5-3.8 mg ATP / g干细胞质量）。木糖发酵产生和积累ATP的速度比混合糖发酵（5％葡萄糖，5％木糖）和混合糖发酵中ATP的产生和积累速率略慢于葡萄糖发酵。结果表明，较高的乙酸水平会延迟发作并影响细胞内的程度ATP积累在较低的pH值下，ATP的产生和积累速率对乙酸最为敏感。

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