USE OF ORGANIC PHOSPHORUS BY RHIZOBIUM-LEGUMINOSARUM BIOVAR VICEAE PHOSPHATASES

Rhizobium leguminosarum biovar viceae strain TAL 1236 growing on diffe rent organic P compounds as sources of phosphate exhibited phosphatase activities. The strain was able to produce both acid and alkaline pho sphatase. However, its ability to produce alkaline phosphatase was muc h higher. When cellular phosphate fell to 0.115% of cell protein, cell ular and extracellular phosphatase activities were enhanced. Mg2+, Co2 + and Ca2+ stimulated the activity of alkaline phosphatase more than a cid phosphatase. However, Mn2+ and Fe2+ activated acid phosphatase rat her than alkaline phosphatase. It may be concluded that R. leguminosar um contributes significantly to the release of P from organic compound s through the action of phosphatase which can be activated by a range of cations.