Livestock systems in Colombia depend on forages, which are established on soils with high phosphorus (P) retention that cause a limitation of the efficiency of phosphate fertilizers. The inoculation of plant growth-promoting bacteria (PGPB) can improve soil P availability through different mechanisms associated with P cycling. The goal of this study was to evaluate the effect of PGPB inoculation on the plant growth under P-deficient conditions as well as to determine the phenotypic and genomic characteristics associated with plant growth promotion. Among nine strains evaluated on P-deficient soil amended with rock phosphate, we selected Rhizobium sp. T88 and Herbaspirillum sp. AP21 for their ability to enhance the dry biomass in perennial ryegrass and red clover, with increases of 20.31 and 44.87%, respectively. Under in vitro conditions, these two selected strains showed the ability to solubilize tricalcium phosphate and rock phosphate by the production of diverse organic acids. It was also observed that both strains produced alkaline and acid phosphatases, while only Herbaspirillum sp. AP21 exhibited phytase synthesis for P mineralization. Finally, in silico genome analysis confirmed that the strains have different features to solubilize and mineralize P, of the 16 reported genes for these metabolic traits, Rhizobium sp. T88 and Herbaspirillum sp. AP21 genome encoded for 7 and 4 genes related to P solubilization, 3 and 6 genes related to P mineralization, respectively. In conclusion, the phenotypic and genomic characterization shows that Rhizobium sp. T88 present mainly mechanism related with P solubilization and Herbaspirillum sp. AP21 with P mineralization.

哥伦比亚的牲畜系统依赖草料，草料建立在磷（P）含量高的土壤上，这会限制磷肥的效率。接种植物促进细菌（PGPB）可以通过与磷循环相关的不同机制来提高土壤磷的利用率。这项研究的目的是评估PGPB接种对缺磷条件下植物生长的影响，并确定与促进植物生长相关的表型和基因组特征。在用磷矿石改良的P缺乏土壤上评估的9个菌株中，我们选择了根瘤菌。T88和螺旋藻sp。AP21增强了多年生黑麦草和红三叶草中干燥生物量的能力，分别增加了20.31和44.87％。在体外条件下，这两个选定的菌株显示出通过产生各种有机酸来溶解磷酸三钙和磷酸岩的能力。还观察到，两种菌株均产生碱性磷酸酶和酸性磷酸酶，而仅草本螺旋藻。AP21表现出植酸酶合成的P矿化作用。最后，计算机基因组分析证实，这些菌株具有不同的溶解和矿化P的特征，这些是这些代谢性状的16个已报道基因Rhizobium sp。T88和螺旋藻sp。AP21基因组分别编码与P增溶相关的7个和4个基因，与P矿化相关的3个和6个基因。总之，表型和基因组特征表明根瘤菌属。T88主要与P增溶和草螺菌有关。AP21具有P矿化作用。