HYDROGELS FOR GROWTH OF LIVING MICRO-ORGANISMS

In this work, I successfully achieved the goals of my PhD project on culturing diatoms, structural colored bacteria, and microalgae in different hydrogels, as well as co-culture bacterial and microalgal cells in the same hydrogel system. In our first project, we developed an innovative approach to study diatoms embedded in hydrogels with controlled conditions, resulting in a straightforward technique to investigate species-specific photo-regulation of benthic diatoms. This work opens an opportunity for further research to better understand how individual diatom species respond to different light conditions and the mechanisms that regulate their endogenic rhythms. In the second project, we have synthesized and characterized various hydrogels with different morphologies as matrices to grow three structural colored bacterial strains. By changing hydrogel compositions and studying their mechanical and physical properties, we successfully developed several methods for the bacteria to form bacterial biofilm with structural color, both in 2D and in 3D hydrogel matrix, which may contribute to further production of sustainable living pigmentations. The co-culture of microalgae and bacteria suggested the microalgal cells can contribute to bacterial growth thanks to the oxygen they produce from photosynthesis. In our last projects, we developed two advanced methods to culture microalgal cells. Microalgal growth in 3D granular hydrogels provides a possible solution for cell aggregation problem in bulk hydrogels. The granular hydrogels are made of fully degradable and highly biocompatible polymers with a facile synthesis method. Due to the interconnected microporous structure, microalgae are able to migrate and proliferate within the hydrogels, enabling faster cell growth, higher photosynthetic efficiency, and less self-shading effect. We also embedded nutrients-encapsulated silica nano-capsules into GelMA hydrogels and used them to culture microalgae, higher cell density and biomass production were achieved by using this culture method, suggesting a potential application to use silica nano-capsules to provide essential nutrients for microalgal cultivation. This work has provided a promising technique for harvesting renewable microalgal bio-resources and have potential applications in both laboratory and industry.