Ultrahigh-Throughput Screening of Metagenomic Libraries Using Droplet Microfluidics.

Droplet microfluidics enables the ultrahigh-throughput screening of the natural or man-made genetic diversity for industrial enzymes, with reduced reagent consumption and lower costs than conventional robotic alternatives. Here we describe an example of metagenomic screening for nucleoside 2'-deoxyribosyl transferases using FACS as a more widespread and accessible alternative than microfluidic on-chip sorters. This protocol can be easily adapted to directed evolution libraries by replacing the library construction steps and to other enzyme activities, e.

Directed evolution of the bacterial endo-β-1,4-glucanase from Streptomyces sp. G12 towards improved catalysts for lignocellulose conversion.

With the aim to develop biocatalysts for enhanced hydrolysis of (hemi)cellulose into monosaccharides, random diversity by directed evolution was introduced in the gene coding for the endo-β-1,4-glucanase from Streptomyces sp. G12 which had been recombinantly expressed in Escherichia coli and named rCelStrep. The main objectives were therefore to set up a complete strategy for creation and automated screening of rCelStrep evolved direct mutants and to apply it to generate and screen a library of 10,000 random mutants to select the most active variants.