Comparative study of the effect of nutrients on motility and chemotaxis of Escherichia coli strains

QR Microbiology

Pandey, Shashank ; Yin, Huabing

University:University of Glasgow

Department:School of Engineering

关键词: Motility;    Chemotaxis;    Microfluidics;    Microfluidic Device;    Imaging;    Single Cell;    Microscopy;    Glucose;    Casamino Acids;    Flagella;    MG1655;    MDS42;    Escherichia coli;    E. coli.;   

Others  :  http://theses.gla.ac.uk/81464/1/2020PandeyMScR.pdf

来源: University of Glasgow

【 摘 要 】

This thesis evaluates two strains of Escherichia coli MG1655 and MDS42 for their motility in different nutrient conditions in M9 minimal medium in 2 parts. It evaluates the effect of genome deletion in the motility and also observes the heterogeneity despite sharing the same genetically encoded machinery. The first part investigates Escherichia coli strains’ motility in 5 different medium compositions and the second part explores the chemotactic response of MG1655 to the linear gradients of different concentrations of Glucose using a single-layer membrane-based microfluidic device.In Part 1, we study the motility of MG1655 and MDS42 in different concentrations of glucose and casamino acids in M9 minimal medium. The motility experiments conducted as a part of this study observed the average cell velocities in the range of 2.9 ± 0.5 μm/s, which are significantly less than the values recorded in literature, for the strain MG1655.The lowest motility occurs in the medium (without casamino acids) with 0M glucose, followed by 10mM Glucose and then 10μM glucose concentration. The same trend is visible in the case of both the strains MG1655 and MDS42. The presence of casamino acids did not significantly affect the motility of MG1655 in the presence or absence of Glucose. Whereas, in the case of MDS42, the casamino acids lower the motility in the presence of Glucose but tend to have no significant effect in the absence of Glucose. The two strains, however, showed no significant difference in average velocity under the same medium conditions.In Part 2, we record and evaluate the chemotaxis of the MG1655 strain, using a single-layer membrane-based microfluidic device. The device generates a linear gradient of 10μM and 10mM glucose, to observe the chemotaxis of the MG1655 strain. The average of mean velocities for the 10μM gradient was higher than those observed in the 10mM gradient, but the difference was not significant. The higher fraction of cells (~67%) under the 10mM gradient showed almost a straight-line trajectory, unlike the cells under 10μM gradient. The cells that followed a nearly straight line path did all the more so in the case of the 10mM glucose gradient.