USE OF ORGANIC PHOSPHORUS BY RHIZOBIUM-LEGUMINOSARUM BIOVAR VICEAE PHOSPHATASES

Rhizobium leguminosarum biovar viceae strain TAL 1236 growing on different organic P compounds as sources of phosphate exhibited phosphatase activities. The strain was able to produce both acid and alkaline phosphatase. 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 enhanced. Mg2+, Co2+ and Ca2+ stimulated 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 R. leguminosarum contributes significantly to the release of P from organic compounds through the action of phosphatase which can be activated by a range of cations.