Probiotic Microbiome: Potassium Solubilization and Plant Productivity

Abstract

The rhizosphere of plant roots supports a range of potassium-solubilizing microbes (KSMs). These KSMs solubilize the insoluble and unavailable potassium (K) to forms of K available for uptake and transport by the plant. Potassium is one of the unavoidable elements required for growth and yield. The specific rhizospheric microbes that perform the process of K solubilization include both bacteria and fungi, the foremost of which are: Bacillus sp. (B. Mucilaginosus, B. megaterium, B. globisporus, B. edaphicus) Pseudomonas putida, Enterobacter hormaechei, Acidothiobacillus ferrooxidans, Paenibacillus sp., and Arthrobacter sp.) Aspergillus terresus, Fusarium oxysporum, Aspergillus fumigatus, and Aspergillus niger. Agricultural soil particulates hold minerals such as illite, biotite, orthoclase, mica, and feldspar that contain potassium; however, this is not accessible to plants due to its immobilized form. In soil chemistry, after N and P, K is an important element; a major role is played by the rhizosphric microbes in mobilizing the inaccessible form of K to the roots of the plant. The rhizospheric K-solubilizing microbes such as Bacillus, Pseudomonas, and Aspergillus expel organic acids, which solubilize the insoluble K and make it available to plant roots. Most of the research work in this area has been conducted on nitrogen fixing and phosphate-solubilizing microbes. Solubilized K (quickly available) in addition to the existing biofertilizers needs additional consideration at a profitable scale. The current chapter presents information to fill the knowledge gaps about K-solubilizing/mobilizing microorganisms in soil, and looks at the current and future facets of K-solubilizing microbes for enhanced crop production.