Isolation, Biomineralization Potential, and Molecular Characterization of Manganese Solubilizing Bacteria and Their Influence on Growth and Manganese Uptake in Maize

Manganese (Mn) is an essential micronutrient for plant growth and plays a critical role in photosynthesis, activation of enzyme, and other metabolic processes. Although Mn is required in small amounts, its bioavailability is frequently poor in problematic soils, resulting in Mn insufficiency in crops. This insufficiency has been a growing issue in several countries. This investigation reports the isolation of total 16 Mn solubilizing bacteria (MSB) from rhizospheric soil and screened most potent strains for their Mn solubilization potential, both qualitatively and quantitatively under in vitro conditions. The most efficient strains were molecularly identified as Bacillus sp. and Psychrobacter sp. through 16S rRNA gene sequencing. The isolated MSB strains were evaluated for multiple plant growth-promoting (PGP) traits, including the production of indole compounds, gibberellic acid (GA3), and siderophores, as well as the solubility of phosphorus (P), potassium (K), silicon (Si), and zinc (Zn), demonstrating their potential as competent growth-enhancing agents. Additionally, through a pot experiment the efficacy of selected MSB strains was evaluated on maize and results revealed a significant enhancement growth and Mn uptake in maize. This study highlights that the MSB12 (Psychrobacter sp.) and MSB14 (Bacillus sp.) could serve as a bioinoculants for alleviating Mn deficiency, enhancing plants health and aid in Mn bioavailability of crops.