Synergistic effect of minerals solubilizing and siderophores producing bacteria as different microbial consortium for growth and nutrient uptake of oats (Avena sativa L.)

Indiscriminate use of chemical fertilizers increases agricultural productivity but on the other hand they harms the health of environment and humans. The multifunctional plant growth promoting bacterial strains could be an ideal alternative to synthetic chemical fertilizers. Looking into the benefits of plant growth promoting bacteria, the present study deals with the isolation of mineral solubilizing and Fe-chelating microbes from the rhizospheric regions of different crops growing in hilly regions of Baru Sahib. Isolated microbes were screened for the multifarious plant growth promoting attributes including solubilization of phosphorus, potassium, zinc, selenium; production of siderophores, ammonia, indole-3-acetic acid, hydrogen cyanide, and nitrogen fixation. The efficient mineral solubilizing and siderophores producing bacterial strains were identified as Serratia surfactantfaciens EU-C3SY2 (P-solubilizer; 144.5 ± 0.05 mg L^− 1), Serratia marcescens EU-D1RNL1 (K- solubilizers; 46.9 ± 1.2 mg mL^− 1), Serratia nematodiphila EU-D2SRY4 (Zn-solubilizer; 68.5 ± 0.03 mg L^− 1), Erwinia persicina EU-B1RT3.1 (Se-solubilizer) and Serratia sp. EU-C1RK1 (siderophores producer; 69.16 ± 0.71 psu) using 16S rRNA gene sequencing. The selected efficient bacterial strains were used for the development of six different microbial consortia, which were evaluated for the growth promotion of oats crops under green house and open field conditions. Among the six different microbial combination, the consortium developed from EU-C3SY2, EU-D1RNL1, EU-D2SRY4, EU-B1RT3.1, and EU-C1RK1 were found as most effective. This microbial combination significantly increased the growth and physiological parameters of oats plants as compared to other developed microbial consortia, control, and agro-chemical fertilizers. The developed mineral solubilizing and Fe-chelating microbial consortium could be used as biofertilizers for crops growing in the hilly regions for agricultural sustainability.