Strategies for the Development of Environmentally Friendly Phosphate Fertilizers Based on Gram-Negative Phosphate Solubilizing Bacteria
The use of rock phosphate ore (RPO) as an environmentally friendly phosphate fertilizer (EFPF) requires the development of sustainable systems capable of generating soluble phosphate (Pi) from this material in a manner that can support crop production. Mineral phosphate solubilizing micro-organisms (MPSM) have routinely demonstrated the ability to drive agronomically viable levels of RPO dissolution and are obvious candidates for the development of EFPFs. The ubiquitous presence of MPS bacteria and fungi in agricultural and native soils throughout the world has fueled a global research effort by agricultural scientists to identify these microbes and to use them to achieve P fertilization. To date, this effort has failed to produce a sustainable fertilizer technology as evidenced by the simple fact that virtually all P fertilizers are still manufactured via sulfuric acid-based “wet processes.” Why have efforts to produce P fertilizers based on MPS microbes been a failure? The answer is, in point of fact, that there has never been a coherent development effort of sufficient duration and intensity to support biotechnology-based strategy for P fertilization of field crops. What has been witnessed in the past 50 years is an uncoordinated, unsophisticated, poorly funded, often redundant cycle of abortive short-term studies mainly related to the identification of P-solubilizing microbes, their biochemical characterization for this property and the evaluation of their ability to enhance plant performance. In contrast to these basic efforts, there have been no investments in the resources necessary to engage in the prolonged, tortuous process of product development. Thus, the fault lies not with the microbes but with the scientific effort, or lack thereof. This report is designed to strategize a way forward for the development of EFPFs based on the Gram-negative MPS bacteria that dissolve RPO and other poorly soluble mineral phosphates via the extracellular generation of powerful organic acids, specifically the solubilization of RPO and other poorly soluble mineral phosphates via the extracellular generation of gluconic and 2-ketogluconic acids using the enzymes of the direct oxidation (DO) pathway.
Gram-negative bacteria, Biological control, Diffusion
Goldstein, A., 2014. Strategies for the Development of Environmentally Friendly Phosphate Fertilizers Based on Gram-Negative Phosphate Solubilizing Bacteria. VFRC Report 2014/5. Virtual Fertilizer Research Center, Washington, D.C. 51 pp.; 5 tables; 27 figs.; 45 refs.