Koch A L, Pinette M F
J Bacteriol. 1987 Aug;169(8):3654-63. doi: 10.1128/jb.169.8.3654-3663.1987.
Gas vesicles were used as probes to measure turgor pressure in Ancylobacter aquaticus. The externally applied pressure required to collapse the vesicles in turgid cells was compared with that in cells whose turgor had been partially or totally removed by adding an impermeable solute to the external medium. Since gram-negative bacteria do not have rigid cell walls, plasmolysis is not expected to occur in the same way as it does in the cells of higher plants. Bacterial cells shrink considerably before plasmolysis occurs in hyperosmotic media. The increase in pressure required to collapse 50% of the vesicles as external osmotic pressure increases is less than predicted from the degree of osmotically inducible shrinkage seen with this organism or with another gram-negative bacterium. This feature complicates the calculation of the turgor pressure as the difference between the collapse pressure of vesicles with and without sucrose present in the medium. We propose a new model of the relationship between turgor pressure and the cell wall stress in gram-negative bacteria based on the behavior of an ideal elastic container when the pressure differential across its surface is decreased. We developed a new curve-fitting technique for evaluating bacterial turgor pressure measurements.
气体囊泡被用作探针来测量水生柄杆菌的膨压。将使肿胀细胞中的囊泡塌陷所需的外部施加压力与通过向外部培养基中添加不可渗透溶质而使膨压部分或完全消除的细胞中的压力进行比较。由于革兰氏阴性菌没有刚性细胞壁，因此预计质壁分离不会以与高等植物细胞相同的方式发生。在高渗培养基中发生质壁分离之前，细菌细胞会大幅收缩。随着外部渗透压增加，使50%的囊泡塌陷所需的压力增加小于根据该生物体或另一种革兰氏阴性菌所观察到的渗透诱导收缩程度所预测的值。这一特征使得将培养基中存在和不存在蔗糖时囊泡的塌陷压力之差作为膨压的计算变得复杂。基于理想弹性容器在其表面压力差减小时的行为，我们提出了一种革兰氏阴性菌膨压与细胞壁应力之间关系的新模型。我们开发了一种新的曲线拟合技术来评估细菌膨压测量值。
