Abstract

High-throughput analysis of cyanobacteria ethanol producers as means of fluorescence in a microdroplet platform

Sara Abalde-Cela, PDRA, University of Cambridge

Ethanol production by microorganisms is increasingly an important renewable energy source. Most processes involve fermentation of sugars from plant feedstock, but increasingly there is interest in direct ethanol production by photosynthetic organisms. However, several challenges remain to optimise the system, and to facilitate this, high-throughput screening techniques for the detection of ethanol are needed. In this paper, we describe a method for the quantitative detection of ethanol in a microdroplets-based platform that can be used for screening cyanobacterial strains to identify those with the highest ethanol productivity levels. The indirect detection of ethanol by enzymatic assay was first optimized both in bulk and in microdroplets. In parallel, we demonstrated the encapsulation of engineered ethanol-producing cyanobacteria in microdroplets, and their growth dynamics in microdroplet reservoirs. The combination of modular microdroplet operations including droplet generation for cyanobacteria encapsulation, droplet re-injection and pico-injection, and laser-induced fluorescence, allowed us to establish a new platform able to screen genetically-engineered strains of cyanobacteria with different levels of ethanol production.