Adaptation of chemical industry to current demand of new products while keeping a profile of low environmental impact is a major challenge. The replacement of complex chemical transformation processes by biological catalysts (biocatalysts) can simplify the process, decrease the amount of chemical solvents used and produce a strong reduction in production costs. The biocatalyst are derived from enzymes, which are proteins produced by living organisms that catalyze the transformation of metabolites and other biological substrates. For their use in the industry, enzymes have to be modified to improve their catalytic properties with the required industrial substrate and to withstand the currently non physiological conditions of industrial use. Modification or discovery of new enzymes suitable for their use as catalysts requires an enormous screening effort, which limits the pace of industrial adaptation. One of the most seek traits in such screenings is thermal stability (), which results in longer use, lesser storage and transportation costs, and functional compatibility with organic solvents.
The HotDrops project was an EU-funded Marie-Curie training and collaborative action that connected four private companies (Novozymes, Galchimia, Biochemize and Droptech) and four academic partners (Universities of Cambridge, Autónoma de Madrid, Vigo and Coruña) around the development of an "Ultra High-throughput platform” for the selection of thermostable proteins. The project combined Microbiology, Genetics, Biochemistry and Microfluidics. This project combined the use of in vivo and in vitro protein expression systems from Escherichia coli and from the thermophilic bacterium Thermus thermophilus in combination with folding reporters that inform indirectly on the of any given protein through the emission of a fluorescent signal. Controlled in water-in-oil microdroplets combined with a fluorescence selection by using microfluidic devices allow for the screening of improbable thermostable enzyme variants among huge numbers of candidates (10e9) in a very short time. Libraries of variants from non-thermostable enzymes and from of thermal origin have been screened through this new high-throughput platform.