Abstract
Hypertonic condition with sucrose at above 0.2_??_0.3M concentration induced the plasmolysis to T. thiooxidans and was accompanied by lowering the activity of respiration. This phenomenon was found to be changeable with pH. At pH 4.0 and above 0.6M sucrose, the activity was lost and recovered at pH 7.0 and above 0.5M sucrose. This suggests that the bacterium has the optimum pH for activity which shifts to more neutrality from acidic side, as the sucrose concentration increases. Colloidal titration was applied to this bacterium in order to estimate the relationship between the variation of respiratory activity and surface charge. This method revealed that T. thiooxidans had little surface charge and that hypertonic condition exerted little influence on the whole surface charge. The reactivity of 2, 4, 6-trinitrobenzenesulfonic acid (TNB) with phospholipid of this bacterium was reduced with increase of the sucrose concentration.
According to these results, authors discussed the change of pH dependency of respiratory activity with osmotic pressure by reference to E. coli plasmolysis and estimated the relationship between the plasmolysis and the reactivity of phospholipid to TNB.
