Solubilização de fosfato por bactérias endofíticas isoladas de bananeira

Abstract

Phosphorus (P) is a limiting macronutrient for production in Brazilian soils, due to their adsorption on soil colloids, which leads to a high cost in phosphate fertilizer applied once the nutrient is not available to plants. The use of endophytic microorganism in phosphorus solubilization has been increasingly accept as an alternative to manage the phosphate fertilizers. Thus, the aim of this study was to evaluate and select endophytic bacteria with high potential for in vitro phosphate solubilization. Forty isolates were evaluated observing their phosphate solubilizing abilities on solid media from different inorganic sources (calcium triphosphate and iron phosphate) and an organic source (lecithin), and the quantification of phosphorus in a liquid medium and evaluation of the phosphatase activity. All assays were performed in a completely randomized design with three replications, and the data submitted to frequency distribution analysis and when statistically necessary to Scott and Knott test at 5% probability. Of the 40 isolates evaluated on solid medium, 67,5% were positive for the solubilization of phosphorus with calcium triphosphate (Ca) (PO4)²), 7.5% for lecithin and none isolate presented ability for solubilizing in iron phosphate (FePO4). The activity of the acid phosphatase was observed in 65% of the isolates, especially the species Aneurinibacillus sp. and Lysinibacillus sp. presenting the best solubilization rates. Quantification phosphorus (P) source in liquid medium supplemented with Ca3(PO4)2 the isolated EB-102 (Bacillus pumilus) presented an average of 15.12 mg L¹, and in the medium supplemented with soy lecithin, the isolate EB-32, genus Bacillus sp. solubilized 2.32 mg L¹ of P. The results of this study pointed variations in P- solubilizing ability and some isolates can be used in future tests in order to evaluated the performance in the field experiments.