Abstracts Earth and Environmental Sciences

Non-invasive optical methodologies to evaluate and enhance Chlorella vulgaris biomass

by Alyssa Smith

Algae are ubiquitous, and essential to life on earth. Due to their diversity and versatility they are of great interest to industry and research. Yet, at present, despite their commercial potential, widespread use of their biomass has faltered, mainly due to pervasive cultivation issues, scalability and financial constraints. Here, some of these issues have been addressed. C. vulgaris biomass was immobilised in agarose hydrogels with added scattering elements to aid light attenuation within the matrix. Cellulose microparticles served as broadband diffusive scatterers which were demonstrated to increase the light path throughout the hydrogel, and the resulting effect on biomass growth was shown to be improved in hydrogels of different thicknesses. Additionally, the foundations for a new non-invasive tool for monitoring biomass growth and physiological condition is presented. Biomass qualities, such as pigment content, were quantified and the spectra for cultures recorded, allowing for machine learning to create linear relationships between the two elements. From this, predictions can be made for biochemical and morphological qualities from the optical fingerprint of the culture alone. Lastly, the optical response of individual cells within a culture were also investigated to understand the effect of a culture on the spectra of the single cells within it, and vice versa, creating a better understanding the optical characteristics of a culture. These investigations have created a toolkit for both increasing the growth of cells in immobilised biomass and a new way in which biomass can be monitored, paving the way for removing the invasive and destructive methodologies currently in use.