Formulation of cost-effective agro residues containing potassium solubilizing bacterial bio-inoculants using response surface methodology

Potassium solubilizing bacteria were isolated from soil samples on potassium aluminum silicate amended agar medium. The bacterial strain B15 recorded the highest potassium solubilization in agar (solubilization index = 2.82) as well as in broth (soluble K = 82.012 μg ml−1) medium. It was identified through 16S rDNA nucleotide sequencing as, Enterobacter hormaechei 1110BP. The strain besides potassium solubilization was also found to have nitrogen fixation and phosphate solubilization abilities. The production of bio-inoculant with this strain was done using locally available agro residues such as wheat bran, sorghum (jowar) bran, and molasses. The usage of agro residues as a nutrient medium in the production of potash bio-inoculant is a novel approach. It is cost-effective as well as environment friendly and it could help to minimize the pollution problems. In the study, response surface methodology was applied for designing the bio-inoculant medium to attain high cell numbers (CFUml−1) and prolonged survival of Enterobacter hormaechei 1110BP. A comparison between the expenses on the synthetic nutrient medium and agro-residue nutrient medium of bio-inoculants reveals that synthetic medium incurs nearly 116.13 times excess than agro-residue medium. Thus, the production of multifarious potash solubilizing Enterobacter hormaechei 1110BP bio-inoculants using locally accessible agro residues is a highly economical and eco-friendly approach for sustainable agriculture. •Enterobacter hormaechei 1110BP is a potent K solubilizer.•Usage of agro residues for liquid K solubilizing bio-inoculant formulation.•Usage of agro residues help to minimize pollution problems and cost-effective.•Formulation of K bio-inoculants medium using RSM to attain high CFU.•Enterobacter hormaechei 1110BP can also provide N and P to plants.