Rare earths (REE) are widely used in high technology, and demand for REE is set to double over the next 30 years. The selective extraction and recycling of REE has a triple challenge: economic, technological and ecological. Currently, less than 1% of REEs are recycled. What's more, extraction methods are tedious and polluting. They require several stages with acids or solvents. The discovery in 2011 of enzymes that naturally use light REE has opened up new prospects. The development of biosourced methods could be a key element in unlocking current selectivity and extraction barriers. This thesis is part of the biotechnologies of tomorrow theme. The aim of this thesis is to acquire fundamental data on the molecular mechanism of a biological system for the selective perception of REE through a robust screening, in order to take advantage of it for the development of biosensors responding to certain specific REE. Cell biology, biochemistry and in silico analysis techniques based on artificial intelligence will be used to accomplish this project. The results obtained will enable us to identify: 1) the molecular mechanism of REE detection and the factors influencing its selectivity, 2) the binding sites of the regulator and the genes involved in this response, and 3) the development from 1) and 2) of robust and selective biosensors.