Phosphatases and the utilization of organic phosphorus by Rhizobium leguminosarum biovar viceae

Rhizobium leguminosarum biovar viceae strain TAL 1236 growing on different organic phosphorus compounds as sources of phosphate exhibited phosphatase activities. The strain was able to produce both acid and alkaline phosphatases. However, its ability to produce alkaline phosphatase was much higher. When cellular phosphate fell to 0.115% of cell protein, cellular and extracellular phosphatase activities were promoted. Mg²⁺, Co²⁺ and Ca²⁺ enhanced slightly the activity of alkaline phosphatase more than acid phosphatase. However, Mn²⁺ and Fe²⁺ activated acid phosphatase rather than alkaline phosphatase. It may be concluded that Rh. leguminosarum plays an important role in the release of phosphorus from its organic compounds through the action of phosphatases which can be slightly activated by a range of cations.