Center of Plant, Soil Interaction and Natural Resources Biotechnology, Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco, Chile.
FEMS Microbiol Ecol. 2011 Jan;75(1):163-72. doi: 10.1111/j.1574-6941.2010.00995.x. Epub 2010 Nov 12.
Phytate is one of the most abundant sources of organic phosphorus (P) in soils, but must be mineralized by phytase-producing bacteria to release P for plant uptake. Microbial inoculants based on Bacillus spp. have been developed commercially, but few studies have evaluated the ecology of these bacteria in the rhizosphere or the types of enzymes that they produce. Here, we studied the diversity of aerobic endospore-forming bacteria (EFB) with the ability to mineralize phytate in the rhizosphere of pasture plants grown in volcanic soils of southern Chile. PCR methods were used to detect candidate phytase-encoding genes and to identify EFB bacteria that carry these genes. This study revealed that the phytate-degrading EFB populations of pasture plants included species of Paenibacillus and Bacillus, which carried genes encoding β-propeller phytase (BPP). Assays of enzymatic activity confirmed the ability of these rhizosphere isolates to degrade phytate. The phytase-encoding genes described here may prove valuable as molecular markers to evaluate the role of EFB in organic P mobilization in the rhizosphere.
植酸是土壤中有机磷（P）最丰富的来源之一，但必须被产植酸酶的细菌矿化，才能释放出可供植物吸收的 P。以芽孢杆菌属（Bacillus spp.）为基础的微生物接种剂已商业化开发，但很少有研究评估这些细菌在根际的生态学或它们产生的酶的类型。在这里，我们研究了智利南部火山土壤中生长的牧草植物根际中具有矿化植酸能力的需氧内生孢子形成细菌（EFB）的多样性。使用 PCR 方法检测编码植酸酶的候选基因，并鉴定携带这些基因的 EFB 细菌。这项研究表明，牧草植物的植酸降解 EFB 种群包括芽孢杆菌属（Paenibacillus）和芽孢杆菌属（Bacillus）的物种，它们携带编码 β-螺桨植酸酶（BPP）的基因。酶活性测定证实了这些根际分离物降解植酸的能力。这里描述的植酸酶编码基因可用作分子标记，以评估 EFB 在根际有机 P 动员中的作用。
