Relationship between the cell surface hydrophobicity and survival of bacteria Zymomonas mobilis after exposures to ethanol, freezing or freeze-drying

An inverse linear relationship (P < 0.01) was detected between the cell surface hydrophobicity (CSH) and survival of ethanologenic bacteria Zymomonas mobilis 113S exposed to elevated (2.55 M) ethanol concentration. In the same way, viable cell counts of relatively hydrophobic Z. mobilis were less diminished by growing (0.85-3.40 M) ethanol concentrations as compared to more hydrophobic bacteria. Very similar inverse relationships (P < 0.01) were observed between the CSH of intact Z. mobilis and survival of cells subjected to subsequent freeze-drying or freezing/thawing cycles thereby affinity substantially lowered ability of hydrophobic bacteria to survive under adverse environments. Observed relationships were supported by significant correlations between independent analytical data of the carbohydrate content within fractions of lipopolysaccharide and surface proteins extracted from cells of varied hydrophobicity. The results suggest that the CSH could be of value to predict the ability of intact bacteria to endure stress conditions and should be monitored towards lower values during cultivation in order to reduce subsequent unwanted structural and physiological disturbances provoked by multiple stress factors.