**4. Phosphorus and microbial communities in the rhizosphere**

The availability of P in the soil can significantly affect the composition and function of microbial communities in the rhizosphere. In P-limited soils, microbial communities can be dominated by species adapted to low P-conditions, such as phosphate-solubilizing bacteria and fungi. These microorganisms can produce organic acids and enzymes that can solubilize P-compounds in soil, making them available for plant uptake. On the other hand, high P levels in soil can harm microbial communities in the rhizosphere. Excessive P can lead to the eutrophication of soil and stimulate the growth of opportunistic microorganisms that are not beneficial for plant growth. Moreover, high levels of P can decrease the diversity of microbial communities in soil, as certain species may become dominant due to their ability to tolerate high P-levels.

In addition to the direct impact of P on microbial communities, the composition of microbial communities in the rhizosphere can also affect P-cycling in soil. For example, mycorrhizal fungi in the rhizosphere can enhance P-uptake and translocation in plants, as these fungi can form symbiotic associations with plant roots and improve nutrient uptake.

The availability of P in the soil can strongly influence microbial community composition in the rhizosphere. For example, high P-levels in soil can decrease the abundance of arbuscular mycorrhizal fungi (AMF) [77]. AMF play a crucial role in

*Representation of the major role of plant-microbe interaction in improving phosphorus availability to plants.*

*Regulation of Plant-Microbe Interactions in the Rhizosphere for Plant Growth and Metabolism… DOI: http://dx.doi.org/10.5772/intechopen.112572*

plant P acquisition, and their reduction can harm plant growth. In contrast, low P levels can increase the abundance of bacteria that can solubilize P [94]. These bacteria can release P from organic compounds and make them available to plants.

Moreover, the form of P in the soil can also affect microbial community composition. Inorganic P, such as phosphate, is soil's most common form of P. However, organic P, such as phytate, is also present in the soil, and its availability is generally low [95]. Some microorganisms, such as phosphate solubilizing bacteria (PSB) and fungi, can convert organic P into inorganic P, making it available to plants. The activity of these microorganisms can be influenced by the plant species and the management practices used in the field [96]. **Figure 4** describes impact of P on microbial communities and plant.
