Development Of Novel Scenedesmus rubescens Mutants With Improved Pigmentation And Protein Contents

Lucas Barata Cardoso

Key information

Authors:

Lucas Barata Cardoso (Lucas Barata Cardoso)

Supervisors:

Mafalda Trovão dos Santos; Marília Clemente Velez Mateus (Marília Clemente Velez Mateus)

Published in

November 21, 2022

Abstract

Common protein sources, such as animal-based food, have a high environmental impact, which will be worsened by the rise in world population and food demand. Microalgae have the potential to be used as alternative protein sources as they are a source of essential amino acids, their cultivation doesn’t require arable land and doesn’t conflict with other food chains. However, microalgae wild-type strains’ high chlorophyll content grants microalgal biomass unpleasant organoleptic properties, which prevents its acceptance. Ethyl methanesulfonate random mutagenesis was used in this work to generate chlorophyll-deficient, and high protein-producing mutants of Scenedesmus rubescens. To isolate the randomly generated mutants a selection platform using nicotine and norflurazon, inhibitors of the carotenoid’s biosynthetic pathway, and InChlo, an inhibitor of the chlorophyll’s biosynthetic pathway, was developed. Four chlorophyll-deficient mutants were isolated: W1 (1.6 mg g-1DCW), W2 (9.2 mg g 1DCW), and W5 (0.6 mg g-1DCW), isolated with nicotine, and Y1 (10.3 mg g-1DCW) which was isolated with InChlo. Mutants W1 and Y1 had a decreased protein content (21 % and 19.1 %), while W2 and W5 maintained their protein content (27.7 % and 25.7 %). Additionally, three mutants, 200a, 300b and 300d, with increased chlorophyll (24.4 mg g-1DCW, 34.4 mg g-1DCW and 27.2 mg g-1DCW) and protein contents (55.7 %, 61.0 % and 59.8 %) were also isolated without using metabolic inhibitors. Among all the isolated mutants, W2 and 300d displayed the highest potential for biotechnological applications, such as feedstock alternatives, cosmetics and nutritional applications.