Results

Plasmolysis

Main objective of this section is to verify the viability of Escherichia coli cells under treatments with polyethylene glycol (PEG 6000) for different time lapses, and the retaken of metabolism after plasmolysis. To this, we submited this organism to different concentrations of PEG 6000 and have assessed its growth hability. Assays of plasmolysis induction were performed using Escherichia coli K-12 strain Dh5α cells obtained from a culture in lysogeny broth until an optical density at 600 nm of ~ 1.5-2.0, finally cells were harvested by centrifugation and washed with sterile 0.9% saline. Cells were resuspended in plasmolysis media (2% (vo./vol.) glycerol, 50 mM sodium acetate, 10 mM zinc chloride) containing various different concentrations of PEG 6000 (5, 10, 15, 20, 25 and 30% wt/vol). Proportion of cells in the final solution was 0.1% wt/vol. All media and their corresponding sterile controls were kept in triplicate at room temperature.

Primary spectrophotometry analysis, by checking optical density at 600 nm of all triplicates with different concentrations of PEG 6000, as well as the control medium without PEG showed cell growth was inhibited with increasing PEG 6000 concentrations used for stress condition induction (Figure 1).

Figure 1: Experimental plot of absorbance versus time in different PEG 6000 concentration.