Bacterial Sample Concentration and Culture Monitoring Using a PEG-Based Osmotic System with Inline Impedance and Voltammetry Measurements
Bacterial Sample Concentration and Culture Monitoring Using a PEG-Based Osmotic System with Inline Impedance and Voltammetry Measurements
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DOI：
10.1007/s41664-019-00096-x
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发表时间：
2019-04
影响因子：
4.7
通讯作者：
Martin K. Kimani;John Mwangi;E. Goluch
中科院分区：
文献类型：
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作者：
Martin K. Kimani;John Mwangi;E. Goluch
使用石墨电极的阻抗测量被用来实时检测由于细菌生长而导致的培养基电导率的增加，同时还使用伏安法监测绿青素的浓度。将电化学方法与使用600 nm光密度(OD600)的浊度测量的细菌培养的传统连续监测进行了比较。进一步设计了一种实用的渗透系统，用于在生长过程中浓缩细菌培养物，以便使用电化学方法进行早期检测。初始培养密度为1 × 108个/m L的细菌培养物在密封的纤维素酯透析膜内生长，膜外用聚乙二醇膜外抽提液逐渐浓缩生长的细菌培养物。以直径0.7 mm的机械铅笔用石墨为工作电极和对电极，以铂丝为参比电极，在有渗透体系和无渗透体系的情况下进行了电化学测量。在没有正向渗透的情况下，阻抗测量检测到培养物生长 ~ 比传统的OD600快1小时。积分渗透法显示，检测作为细菌生长指标的绿青素产生的时间减少了两倍。对于阻抗监测，渗透除水与细胞生长引起的阻抗下降混为一谈；然而，结果表明，当样品中存在细菌时，通过观察到渗透阻抗曲线的变化，可以很有希望地检测细菌的生长。通过监测阻抗曲线的偏差，与传统的OD600测量相比，检测时间缩短了三倍。
Impedance measurements using graphite electrodes were used to detect the increase in culture medium conductivity due to bacteria growth in real time along with simultaneous voltammetric monitoring of pyocyanin concentration. Electrochemical methods were compared to conventional continuous monitoring of bacterial cultures using turbidity measurement at an optical density of 600 nm (OD600). A practical osmotic system was further designed for concentrating bacterial cultures during growth to enable earlier detection using the electrochemical methods. Bacterial cultures, starting from an initial culture density of 1 × 108cells/mL, were grown inside a sealed cellulose ester dialysis membrane, while polyethylene glycol in LB medium was used as the draw solution outside the membrane to gradually concentrate the growing cultures. 0.7-mm-diameter graphite for mechanical pencils was utilized as working and counter electrodes with a platinum wire reference electrode for electrochemical measurements with and without the osmotic system. In the absence of forward osmosis, impedance measurements detected culture growth ~ 1 h faster than conventional OD600. Integrating osmosis showed a twofold decrease in the time to detect pyocyanin production as an indicator for bacterial growth. For impedance monitoring, removal of water by osmosis was conflated with the impedance decrease due to cell growth; however, the results show a promising ability to detect bacteria growth via an observed shift in osmotic impedance profile when bacteria are present in a sample. By monitoring the deviation in the impedance profile, a threefold improvement in detection time was achieved when compared to conventional OD600 measurements.