Reprocessing waste into chlorella vulgaris biomass – A strategy of developing next-generation food and feed

Abstract

Humanity is confronted with over population joined with increasing greenhouse gas emissions and advancing depletion of the world’s resources. Thus, alternative food and feed sources are strongly demanded. Microalgae arouse attention due to their capability of converting light into highly nutritious biomass and fixating the greenhouse gas CO2. However, the cultivation of microalgae in a sustainable and economically-viable manner is still in the developing phase.In this thesis, a new approach of using wheat straw hydrolysates (WSH) as a substrate for Chlorella vulgaris was studied. While C. vulgaris is a well-known food and feed microalgae,wheat straw is an abundantly occurring lignocellulosic waste product. Reprocessing WSH intoC. vulgaris biomass has the potential to reduce cultivation cost and enhance sustainability.Growth parameters and biochemical composition of C. vulgaris in different concentrated WSHunder mixotrophic and heterotrophic conditions were studied. Results were compared to the cultivation of C. vulgaris in a defined medium and to a photoautotrophic control culture. While mixotrophic conditions in WSH showed 1,5-fold higher biomass concentration compared to photoautotrophic cultivation, heterotrophic cultivation resulted in 4-times lower biomass concentration. The cultivation of C. vulgaris in WSH had no adverse effect on the protein and chlorophyll content, being crucial parameters for the food and feed market. Hence, the usage of WSH as a substrate for C. vulgaris still has the potential to reduce processing costs, but research on optimising growth performance is required.