CONICET | Buscador de Institutos y Recursos Humanos

Lead (Pb) is a toxic heavy metal used by humans in some industries. Exposure to this metal accounts for over 850,000 deaths worldwide each year. 'Clean' technologies, like electric cars, often employ traditional Pb-based batteries; the disposal of these batteries is a leading contributor to Pb pollution in drinking water. It is worth noting that the World Health Organization (WHO) limit for lead in drinking water is 10 parts per billion (ppb). The use of chemical methods for the detection of heavy metals requires complex and expensive equipment that can only be used by a specialist. Additionally, measurement in remote locations requires transport of samples to centralized testing facilities, resulting in a delay between sample collection and measurement. So, there is a high demand for complementary and alternative in situ detection methods. The device we propose to develop will use inorganic Pb biosensing E. coli bacteria. This study utilizes synthetic biology principles to develop plasmid-based whole-cell bacterial biosensors for detection of lead. The lead biosensor design is based on the natural metal detoxification mechanism of the Cupriavidus metallidurans (previously Ralstonia metallidurans) CH34 strain. The genetic element of the lead biosensor construct consists of PbrR1 or PbrR2 genes sequences, which encodes the lead-specific binding proteins (regulatory proteins), together with their respective divergent promoter regions that, depending on the presence or absence of lead, regulate the expression of a reporter gene (GFP/NanoLuciferase/BGalactosidase). Preliminary results obtained with the PbrR1-based plasmids presented good sensitivity at very low levels but showed high variability between assays and high basal expression of the reporter protein. An improved device based on PbrR2 gene has been designed and the experiments will be performed soon. The final goal is to make widely-distributed metrology and real-time, crowd-sourced monitoring of lead levels in drinking water by using a custom sensor assembly box that plugs into a mobile phone to acquire and analyze the data.