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.