AUTHOR=Schambach Jenna Y. , Kruse Colin P. S. , Kitin Peter , Mays Wittney , Hunt Christopher G. , Starkenburg Shawn R. , Barry Amanda N. 

TITLE=Metabolism of Scenedesmus obliquus cultivated with raw plant substrates

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.992702

DOI=10.3389/fpls.2022.992702

ISSN=1664-462X

ABSTRACT=<p>The potential benefits of adding raw, non-food, lignocellulosic plant material as a carbon source for mixotrophic growth of microalgae have previously been demonstrated. This approach has advantages over using traditional carbon sources like glucose or acetate due to wide-spread plant biomass availability and substrate recalcitrance to bacterial contamination. Here, we report the overall growth characteristics and explore the metabolic patterns of <italic>Scenedesmus obliquus</italic> cultured in the presence raw plant substrate. An initial screen of plant substrate candidates showed an increase in specific growth rate and biomass accumulation when <italic>S. obliquus</italic> was cultured in the presence of switchgrass or yard waste compared to media alone. We observed a near doubling of microalgal dry weight when <italic>S. obliquus</italic> was grown with 0.2% (<italic>w/v</italic>) switchgrass under ambient CO<sub>2</sub>. Scanning electron microscopy (SEM) of corn stem after <italic>S. obliquus</italic> cultivation exhibited substantial phloem degradation. Transcriptomic analyses of <italic>S. obliquus</italic> during mid- and late-log phase growth revealed a dynamic metabolic landscape within many KEGG pathways. Notably, differential expression was observed for several potential glycosyl hydrolases. We also investigated the influence of switchgrass on the growth of <italic>S. obliquus</italic> at 50 L volume in mini raceway ponds to determine the scalability of this approach.</p>