Bacterial solubilization of mineral phosphates: Historical perspective and future prospects

Abstract

Maximum crop yields require sufficient phosphorus fertilization. Only phosphate in a soluble ionic form (Pi) is effective as a mineral nutrient. Current fertilizer technology supplies the soil solution with Pi via the application of large amounts of phosphate salts. Problems with this technology include energy-intensive production processes, the need for large scale mechanical application with associated environmental consequences, and reprecipitation of the phosphate into insoluble mineral complexes. It has been estimated that in some soils up to 75% of applied phosphate fertilizer may be lost to the plant because of mineral phase reprecipitation. Many approaches, ranging from cultural practices to biological inoculants such as mycorrhizal fungi, are being employed to enhance P-use efficiency. One area that is currently under-investigated is the ability of certain types of bacteria to solubilize mineral and organic phosphates. A review of the literature in the area of bacterial phosphate solubilization confirms that this trait is displayed by a wide range of bacteria. The phosphate starvation inducible (PSI) organic phosphate-solubilizing capability of E. coli is a component of a coordinately regulated gene system: the pho regulon. It has long been known that bacteria are also capable of solubilizing mineral phosphates such as hydroxyapatite. To date there has been no systematic study of the genetics of this phenomenon. Data from my laboratory indicate that the bacterial mineral phosphate-solubilizing (MPS) trait is regulated by the external level of Pi This conclusion is supported by results obtained from several types of molecular genetic studies. It is proposed that bacteria have mineral phosphate solubilizing (mps) genes. The potential agronomic applications of bacterial mineral and organic P solubilizing systems are discussed.

Characterization of plant growth-promoting rhizobacterium Exiguobacterium NII-0906 for its growth promotion of cowpea (Vigna unguiculata)

“…Several studies have examined the ability of different bacterial species to solubilize the insoluble inorganic phosphate compounds, such as tricalcium phosphate, dicalcium phosphate, hydroxyapatite, and rock phosphate (Goldstein 1986;Rodriguez & Fraga, 1999;Vassilev & Vassileva 2003), such as Pseudomonas, Bacillus, Rhizobium, Burkholderia, Achromobacter, Agrobacterium, Micrococcus, Aereobacter, Flavobacterium and Erwinia. A considerably higher concentration of phosphate solubilizing bacteria is commonly found in the rhizosphere in comparison with non-rhizosphere soil (Sperberg 1958;Katznelson et al 1962;Raghu & MacRae 1966;Alexander 1977).…”

Rock phosphate dissolution by specific yeast

“…Sustainable P supply in agro ecosystem can be achieved by using rock phosphate in conjunction with PSM [12,13]. Microbial volatilization of rock phosphate (RP) especially low grade and its use in agriculture is receiving greater attention.…”

Pyrroloquinoline Quinone Biosynthesis GenepqqC, a Novel Molecular Marker for Studying the Phylogeny and Diversity of Phosphate-Solubilizing Pseudomonads

“…Phosphorus (P) is an essential macroelement for plants, and its bioavailability is often limited in soil because it forms highly insoluble iron-aluminum oxide complexes (11). Several bacteria are known to solubilize phosphate from these soil complexes, rendering phosphorus available to plants and thereby improving plant growth.…”