A combination of Zinc solubilizing bacteria and ZnO nanoparticles alleviates the toxicity of Ag and TiO2 nanoparticles in Mung bean

Abstract

Zinc-deficiency, a global health challenge affects one-third of the world population. Zinc solubilizing bacteria (ZSB) increases plant vegetative growth, grain’s Zn-content ensuring improved dietary Zn-supply offering an efficient and cost-effective solution. This study aimed at understanding that how the presence of two soil abundant nanoparticles silver and titanium dioxide in the rhizosphere influences the activity of ZSB and plant’s vegetative growth. Two ZSB strains D-7 and D-117 with good zinc solubilization efficiency of 254 and 260%, respectively were used with ZnO-NPs for Zn fortification of Mung bean in the presence of various doses of TiO2 and Ag-NPs. Two sets of pots, were used, one containing ZSB, Mung bean seeds, ZnO-NPs (20 mg kg− 1 soil) and various doses of nanoparticles. ZSB-free pots were used as control. The plants were studied for change in rate of seed germination, vegetative growth (shoot and root length, fresh and dry weight), photosynthetic pigment and Zn-content. Lower dose of nanomaterials (50 and 100 mg kg− 1 soil) slightly promoted the plant growth compared to control. While, higher doses (200 and 400 mg kg− 1 soil) inhibited the growth. A maximum decrease of shoot length, root length, fresh-weight, and dry-weight of 37.5, 62.3, 57.1, and 53.2%, respectively was observed with 400 mg kg− 1 soil of Ag-NPs. In the presence of ZSB the decrease was 34.8, 21.3, 41.6, and 37.9, respectively with the same concentration of Ag-NPs. Results presented in this study demonstrate that ZSB alleviate the toxicity of the nanoparticles and improves Zn content in Mung bean.