Potassium solubilizing bacteria (KSB): Framework, stimulation of plant growth and future outlook: A review

Abstract

Potassium (K) is an essential macronutrient required for the fundamental growth and physiological development of all plants and animals. It is absorbed by plant roots and circulates throughout the organism as the cation K+. Although global soil reserves of potassium are typically high, the vast majority exists as insoluble minerals, meaning plants can only access a very small fraction of this total. This limitation has made modern agriculture heavily dependent on expensive synthetic fertilizers, which can degrade soil health over time. Potassium-solubilizing bacteria (KSB) offer a powerful biological solution by converting these inaccessible mineral forms into usable nutrients. Diverse bacteria, including Acidothiobacillus ferrooxidans, Paenibacillus spp., and various Bacillus species, have demonstrated the ability to dissolve silicate minerals such as biotite, feldspar, and mica. These microbes utilize a suite of biological processes including the secretion of organic and inorganic acids, acidolysis, polysaccharides, chelation, and exchange processes to release K into the soil solution. Utilizing KSB in integrated nutrient management not only boosts soil K availability but also promotes sustainable farming by reducing the reliance on chemical inputs. This review explores the framework of KSB, the specific biochemical pathways they use to solubilize K, and their multi-functional role in promoting plant development and crop yield. By addressing current challenges and outlining future research directions, this article underscores the importance of KSB as a cornerstone for sustainable global food security.