Formulation of a consortium-based Zn biofertilizer, and its quality control, to improve Zn status of wheat grains and Wistar rat blood plasma.

Zn-deficiency causes immense losses to agriculture and leads to various human health issues adding to the burden on the global healthcare system. Growing zinc-dense cereals using Zn-biofertilizer is one of the most enticing solutions to the problem. In this study a Zn-biofertilizer containing a consortium of Zn-solubilizing strains of Streptomyces sp., Pseudomonas sp. and Zinc oxide nanoparticles as source of Zn was prepared. Strains showing an excellent Zn-solubilization efficiency (>200%), additional plant-growth-promoting traits, abiotic stress tolerance, and root colonization were selected. Seven experiments, mainly comparing the influence of bulk and nano-ZnO as Zn-sources in combination with the prepared Zn-biofertilizer on wheat plant growth and grain Zn-fortification were performed. When wheat plants were grown in the presence of prepared biofertilizer and nano-ZnO a significant increase in plant vegetative growth and grain yield was observed. A 35.1%, 60.5% and 67.2% increase in total- plant length, fresh and dry-weight respectively, was observed compared to the control. Similarly, wheat grains per spike, grain yield, and grain protein increased by 17.0%, 13.9%, and 47.5%, respectively. The Atomic Absorption Spectroscopy and SEM-EDX of wheat grains grown with biofertilizer and nano-ZnO reveal a high Zn-content (43.0 ± 0.5 mg kg^-1) in the grains. The AAS analysis of the blood from Wistar rats fed with Zn-dense wheat flour obtained in the study shows a higher Zn-content (7.79 ± 0.18 μg ml^-1) in the blood than those fed with control flour. This study conclusively proves that the prepared Zn-biofertilizer with ZnO-nanoparticles can improve the Zn-content of wheat, consequently increasing blood Zn-content in rats.