Fig. 7: Quantitative assessment of GV yield in E. coli by hydrostatic collapse assay.
a Schematic representation of the hydrostatic collapse assay setup used to analyze GV samples. The system comprises a Nitrogen (N2) tank with a pressure controller connected to a sealed optical cuvette containing the suspended GV samples. Hydrostatic pressure is incrementally applied, and the optical density at 500 nm (OD500) is monitored using a spectrophotometer to assess the collapse behavior of GVs under increasing pressure. b Schematic representation and representative images of 6 M urea-treated wild-type pNL29 GV samples before (−) and after (+) hydrostatic collapse. The GV samples exhibit decreased turbidity, corresponding to a reduced OD500 value after hydrostatic collapse. c Hydrostatic collapse profile for purified 6 M urea-treated wild-type pNL29 GV samples. The hydrostatic collapse data were fitted using a Boltzmann sigmoidal regression model, depicted as a grey curve, yielding a coefficient of determination (R2) of 0.9437. Hydrostatic collapse profiles of wild-type pNL29 GV-operon-expressing E. coli cultures. Cultures were induced with 0 µM (d), 200 µM (e), and 400 µM (f) IPTG. WT 20 µM IPTG serves as the control. Data represent mean ± s.d for n = 6 biologically independent samples. All data were fitted using a Boltzmann sigmoidal regression model (curves with respective colors), with corresponding R2 values indicated for each IPTG concentration. Normalized absorbance values in (c–f) are expressed in absorbance units (AU) on the y-axis. Data in (c–f) represent mean ± s.d for n = 6 biologically independent samples for all groups.
