Iron pyrite, a potential photovoltaic material, increases plant biomass upon seed pretreatment

Abstract

Iron pyrite (FeS₂) is a promising material with plethora of applications ranging from sulfuric acid production to photo-voltaic devices. Interestingly, the proponents of the theory of hydrothermal origin of life on earth argues that FeS₂ may have evolved 4.0 billion years ago, and used as an energy source by the earliest evolving life forms on earth. In the present time, bacteria like Thiobacillus ferrooxidans, which survives in the oxygen deficient environments, derives energy solely from FeS₂ to maintain its critical biomass. The key question, we addressed in this paper is 'whether higher plants have the ability to derive energy solely from FeS₂, just like the way Thiobacillus species does.' To answer this question, we developed a novel, inexpensive, low temperature scheme (< 100 °C) for FeS₂ synthesis. We characterize FeS₂ using X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) techniques. Further, we pretreated the chick-pea (Legume) seeds for 12 hours in sterile, double distilled aqueous medium of dispersed FeS₂ (80 μg/ml). Following this, we allowed these seeds to grow in sterile, double distilled water for 7 days. At this stage, we observed that FeS₂ pre-treated seeds result in significantly healthier plants, with increased dryweight and enhanced sulfur content as compared to the control plants. In summary, a brief FeS₂ pre-treatment of the seeds resulted in increased plant biomass. This study has drawn an evolutionary consilience between two diverse life forms in terms of their ability to use a common pre-biotic energy molecule for biomass production. Our results suggest that FeS₂ apart from its opto-electronic potential, could also be used as a pro-fertilizer for sustainable agriculture practices.