Phosphorus and phosphate solubilizing bacteria: Keys for sustainable agriculture

Phosphorus (P) is one of the most important minerals required for plant growth occupying a strong position among soil macro nutrients. Soil P deficiency is often fulfilled by phosphate fertilizers. P deficiency in soils is due to less total P contents in the soil and fixation of added P from chemical fertilizers as well as other organic sources like manures. The response of plant under P stress or even when it is present in adequate amount is very mild. The basic constraint in the availability of P is its solubilization as it gets fixed both in acidic and alkaline soil. Soil fixed P can only be solubilized by phosphate solubilizing microorganisms (PSMs).These bacteria released different types of organic acids in the soil which make P soluble and available to plants. The potential of these PSMs to solubilize P varies and mainly depends upon mechanism adopted for solubilization, their molecular genetics as well as their ability to release P in soil. The PSMs, having all the characteristics of phytohormone production, nitrogen fixation, as well as, heavy metal decontamination and creating salt stress tolerance in plants, are quite rare for sustainable agriculture. Application of this environment friendly approach for increasing crop productivity as well as its impact on soil and plant health is discussed in this review which will not only open new avenues of research but also provide fruitful information about phosphate solubilizing microbes for sustainable agriculture development.