Influence of water on the primary photosynthetic activity of Rhodospirillum rubrum in reverse micelles

The effect of water on the primary photosynthetic activity of purple bacter ium Rhodospirillum rubrum was studied in Hexadecane-Tween-Spane (HTS)- and phospholipid (PLC)-reverse micelles. Reverse micelles offer the possibility of modulating the amount of water to which enzymes and multienzymatic comp lexes are exposed. Fast bacteriochlorophyll (BChl) fluorescence induction k inetics and reaction centre absorption changes at 820 nn were used as an as say for the functional transfer of bacterial cells into I HTS-reverse micel les and bacterial photosynthetic complexes (BPC) into PLC-reverse micelles. Both the bacterial cells and BPC showed an increase in the rate of primary photosynthetic activity by increasing the concentration of water in the re verse micelles. The bacterial cells could be kept viable for many hours in MTS-reverse micelles in presence of 6 % (v/v) water. NMR studies indicated that the photosynthetic activity was affected by the availability of water in reverse micelles. The bacterial cells in HTS or BPC in PLC reverse micel les could be used to further understand the influence of water on the organ isation and function of photosynthetic complexes.