Effect of bacteria and amoebae on rhizosphere phosphatase activity.

The contributions of various components of soil microflora and microfauna to rhizosphere phosphatase activity were determined with hydroponic cultures. Three treatments were employed: (i) plants alone (Bouteloua gracilis (H.B.K.) Lag. ex Steud.) (ii) plants plus bacteria (Pseudomonas sp.), and (iii) plants plus bacteria plus amoebae (Acanthamoeba sp.). No alkaline phosphatase was detected, but an appreciable amount of acid phosphatase activity (120 to 500 nmol of p-nitrophenylphosphate hydrolyzed per h per plant) was found in the root culture solutions. The presence of bacteria or bacteria and amoebae increased the amount of acid phosphatase in solution, and properties of additional activity were identical to properties of plant acid phosphatase. The presence of bacteria or bacteria and amoebae increased both solution and root phosphatase activities at most initial phosphate concentrations.