Localizing Anaerobic Microbial Cultivation and Recovery Through Intelligent Pickering Emulsion Phase Inversion

Abstract

Microbial cultivation in microcompartments using water-in-oil (w/o) emulsion droplets has greatly advanced the study of strict anaerobic bacteria. However, a major challenge lies in the separation and recovery of the bacterial liquid. In this study, we address this challenge by localizing strict anaerobes within w/o Pickering emulsion droplets stabilized by modified microgel particles. This approach demonstrates remarkable efficiency in bacterial microencapsulation, growth and separation. The microgel particles are modified in-situ with hydrophobic silica allowing for stabilization of w/o emulsions at the optimum cultivation temperature of 37 °C while the continuous oil phase prevents oxygen ingress thereby maximizing anaerobic fermentation. Additionally, a temperature decrease triggers the microgel particles to swell and become hydrophilic, causing an immediate inversion of the emulsion to oil-in-water type. This facilitates complete separation and collection of the bacterial suspension without any damage or loss. The intelligent phase inversion of the emulsion presents exciting possibilities for various applications in anaerobic fermentation, synthetic biology and biomanufacturing.