Bacillus subtilis immobilization in alginate microfluidic-based microparticles aiming to improve lipase productivity

Biocatalyst immobilization is an important strategy to improve bioprocess productivity. However, conventional immobilization techniques produce non-uniform particles of millimetric size that may affect the cellular response by limiting nutrient transport into the particles. Droplet-based microfluidics can be an alternative to generate homogeneous and micrometric particles resulting in a reduced nutrient diffusion path when compared to conventional immobilization processes. Although the immobilization process by microfluidics has several applications in biological studies, this technology has been hardly employed in industrial bioprocesses. In this work, we present microfluidics as a potential tool for bacteria immobilization and their use in bioprocess. We studied the immobilization of Bacillus subtilis in alginate microparticles and evaluated their application in batch cultivations to increase the productivity of lipase, an enzyme of commercial interest. Since this is a proof of concept study, we used the free cell cultivation as reference. In comparison with free cell cultivation, the batch cultivation with immobilized cells by the microfluidic technique presented almost 3 times higher lipase production as a result of the high cell concentration. Therefore, the application of a droplet-based microfluidic technique for cell immobilization in alginate microparticles is an alternative to increase productivity in industrial biotechnology.