Heavy metal contamination of water from mining and industrial processes possesses a serious threat to human health and the entire biosphere. We are investigating biologically—based means to soak up heavy metals and to lock them into stable mineral structures and thereby decontaminate metal—polluted waters. The key to accomplishing this, we believe, lies in our recent discovery that cyanobacteria (blue—green algae) can be stimulated to produce more negative charge on their cell coatings, called cEPS, which in turn binds the positively charged heavy metals. This stimulation is elicited when the cyanobacteria are exposed to high levels of carbon dioxide that approximate levels found in flue gas from coal and natural gas power plants. In addition to binding heavy metals, the negatively—charged cEPS can incorporate them into a mineral similar to limestone when enough limestone precursors, such as cheap and plentiful calcium hydroxide, are present. Our proposed research seeks to demonstrate and characterize the carbon dioxide—induced negative charging of cEPS in the cyanobacterial genus Nostoc because several strains of Nostoc accumulate copious amounts of cEPS that can be harvested from the cells without killing them, analogous to picking fruit from a tree. Another benefit of Nostoc is that they can grow without the need for nitrogen fertilizer owing to their ability to use nitrogen gas from the air. Should we find optimal means to produce and harvest highly negatively charged cEPS from Nostoc, we expect that large scale cEPS—based remediation of heavy metal—contaminated waters will become feasible.
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- United States-Israel Binational Science Foundation (BSF)