Microorganisms as a Sustainable Alternative to Traditional Biofortification of Iron and Zinc: Status and Prospect to Combat Hidden Hunger

Abstract

Despite the fact that the world has achieved adequate food grain production to fight the battle against caloric hunger, still, a significant fraction of population is suffering with deficiency of micronutrients like Fe and Zn. However, the dietary intake of these micronutrients could be sufficient to meet the nutritional demand if the bioavailability was not low due to the strong inhibition by phytic acid and phenolics. Another cause behind inadequate intake is the scarcity of plant-available micronutrients in soil and genetic makeup of plants impeding high accumulation. Postharvest fortification is the major strategy to enrich staple food crops with micronutrients, but biofortification of food crops using breeding and agronomic strategies is also gaining popularity. However, one important issue remained unaddressed as none of them could really increase the plant-available micronutrients like Fe or Zn which otherwise remain insoluble in soil. Microorganisms due to their enormous metabolic diversity are known to be key players in biogeochemical cycling. Their roles in improving the uptake of major nutrients by plants are well-known and understood. Enrichment of edible crops with Fe and Zn can be achieved through microorganisms by any of the three following strategies—(a) increased availability of micronutrients due to microbial activity such as production of acids, chelators, and phytohormones; (b) microbe-mediated modulation of micronutrient transporters; and (c) de-complexation of micronutrients from compounds like phytate through microbial activity during postharvest processing. Microbe-mediated biofortification can potentially complement the agronomic and genetic biofortification of staple crops.