Digital recordings of gas-vesicle collapse used to measure turgor pressure and cell–water relations of cyanobacterial cells

摘要: Abstract The gas vesicles of the cyanobacterium Microcystis sp. collapse under pressures ranging from 0.65–1.10 MPa, determined turbidity changes in a pressure nephelometer. In turgid cells, occurs at lower range pressures; difference is equal to cell turgor pressure. decreases, however, as collapse; this decrease minimised by calculating samples with few their collapsed. Previously, and were measured discrete steps, using analogue meters, or continuously, chart recorders: was calculated mean median pressures. We describe modifications allowing continuous digital recording; output modelled polynomial sigmoid functions, latter providing best fit over full collapse-pressure curve; could then be for any point on curve. shape curve affected rate rise; curves similar those step-wise methods when raised approximately 4 kPa s − 1 . Under rapid, almost instantaneous, rise there larger initial subsequent recovery hydraulic conductivity surface calculated; new method gave improved measurements volumetric elastic modulus. Following half vesicles, cells recovered after 3 h. This suggests homeostasis. These are applicable other bacteria including Escherichia coli , if it genetically modified express transgenic vesicles.