Considering that one way for providing available phosphate to plants is by the microbial activity for the mineralization of organic phosphorus, the influence of plants (Brachiaria ruziziensis, Cajanus cajan and control), fertilizers (superphosphate, rock phosphate and control) and liming (with and without lime) was evaluated in the microorganisms populations of the acid and alkaline phosphatase producers. Among bacteria, 70,6% showed alkaline phosphatase activity and 58,2% acid phosphatase activity and among fungi, 64,3% and 84,7%, respectively. These numbers show that a significant population of microorganisms shows ability for organic phosphorus mineralization. Restrictive effect of the C. cajan was observed on the bacteria and fungi producers of the alkaline and acid phosphatases whose numbers always were lower to those obtained with the B. ruziziensis or with the plots without cultivation. Larger number of alkaline phosphatase bacterial producers was obtained in the treatments with superphosphate and control than that with rock phosphate. On the opposite, for fungi, a larger number was found in the plots with no fertilizer compared to the ones with fertilizer. The population of fungi having acid phosphatase activity decreased in the limed plots whereas the bacterial population increased. Finally, the alkaline phosphatase bacterial producers showed higher enzymatic activity than those of the fungi.
bacteria; fungi; acid phosphatase; alkaline phosphatase; rock phosphate; superphosphate; Brachiaria ruziziensis; Cajanus cajan; liming
