Bactérias solubilizadoras de fosfato inorgânico em solo preservado e antropizado da reserva biológica de Pedra Talhada - AL

Abstract

In general, the soils of the tropical and humid regions are quite intemperate and acidic, presenting high maximum phosphorus adsorption capacity due to the high affinity of this element with iron, aluminum and calcium. Due to this, the application of phosphate fertilizers has low efficiency, around 10 to 25%. The microorganisms present in the soil have a role of extreme relevance in the availability of phosphorus for the plants. These microorganisms, mainly bacteria and fungi, present two mechanisms of phosphorus release for soil solution: solubilization reactions of inorganic phosphorus and mineralization of organic phosphorus. In this sense, the inoculation and maintenance of such beings is of paramount importance to replace or decrease the use of soluble phosphate fertilizers, improving the utilization of existing natural phosphates or added to the soil and application of soluble sources, thus, contributing to reduce dependence on imported fertilizers, the costs of agricultural production and also environmental impacts. Therefore, the objective of this work was to evaluate the inorganic phosphate-solubilizing bacterial community in soils under cover of agriculture, native forest and pasture of the Biological Reserve at Pedra Talhada located in Quebrangulo – AL. Isolation Bacterial was performed in a culture medium specific to inorganic phosphate solubilizing bacteria. The estimate of the total bacterial population was quantified by colony-forming units per gram of soil (UFC g -1 ). Isolates were selected to quantify their solubilization capacity. Every 3 days, the diameters of the colonies and solubilization halos were measured with the aid of a digital caliper to determine the Solubilization Index (IS), defined by the ratio between the average diameter of the solubilization halo and the average diameter of the colony bacterial. It was observed that the bacterial population density solubilizing of inorganic phosphate ranged from 2·106 (forest) to 1·109 (pasture) UFC g -1. There was no significant difference between the areas in relation to the total bacteria. However, there was a significant difference between the areas in relation to bacteria capable of solubilizing inorganic phosphate and non-solubilizers. The pasture area presented the largest bacterial population solubilizing of inorganic phosphate; while the forest area, smaller. Most isolates presented low solubilization capacity, only the isolate AL-26 stood out, presenting a mean ability to solubilize. It may later be further explored in experiments to promote plant growth.