RATIONAL DESIGN OF WHOLE-CELL METAL BIOSENSORS AND BIOTECHNOLOGICAL TOOLS TO REMEDIATE THESE INTOXICANTS.

CHECA SK

Chapadmalal

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiología General; 2023

Sociedad Argentina de Microbiología General

Heavy metal contamination of water is a direct consequence of anthropogenic activities and a growing global concern. These persistent intoxicants accumulate in organs and tissues, causing irreversible damage, that ends in chronic disease and/or teratogenic effects. The risk is directly linked to heavy metal bioavailability, that is, the fraction capable of crossing biological membranes and impacting macromolecules. Mercury (Hg), lead (Pb) and cadmium (Cd) are listed by the World Health Organization and other protection agencies among the most harmful chemicals, and these agencies established maximum tolerance levels to guarantee water quality. The methodologies used to monitor these metals require facilities that are only available in specialized laboratories usually placed in large cities. While these methods are specific and sensitive, they are expensive and do not discriminate the bioavailable fraction, thus not serving as direct indicators of risk. Furthermore, the techniques used to remove these toxic metals from water are complex and inefficient, and not environmentally friendly, since they generate highly contaminated solid waste. Bacteria naturally detect and respond to toxic metal ions and can even alter their bioavailability. Advances in genetic engineering, molecular biotechnology and synthetic biology allow us to manipulate these microorganisms and generate accessible and ecological tools to detect and remediate these intoxicants. My group has characterized some of the regulatory pathways involved in metal resistance and applied our knowledge to the design of biotechnological tools that report water metal contamination. Of particular relevance to this presentation is GolS, an efficient gold (Au) sensor and transcriptional regulator from Salmonella. We previously used GolS, along with one of its target promoters, to generate a modular biosensing platform and a biosensor to report this toxic metal. We also generated non-specific variants of GolS that allowed us to developed a set of whole-cell biosensors that detect the presence of bioavailable Hg, Pb and/or Cd, as well as other metals. In this presentation I will focus on our latest contributions to this field. I will explain how we transformed GolS into an efficient Hg(II) detector and obtained a biosensor that specifically reports and quantifies this contaminant using an affordable and user-friendly protocol. This in turn allowed us to understand how the protein scaffold influences these regulators metal-detection affinity and/or specificity. This knowledge is letting us to developing new GolS derivatives to complete a panel of bioanalytical tools. We are also working on enhancing the capabilities of the Hg biosensor and generating bacteria capable of efficiently removing this toxin from water.