Metabolism of Scenedesmus obliquus cultivated with raw plant substrates

Abstract

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 Scenedesmus obliquus 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 S. obliquus was cultured in the presence of switchgrass or yard waste compared to media alone. We observed a near doubling of microalgal dry weight when S. obliquus was grown with 0.2% (w/v) switchgrass under ambient CO2. Scanning electron microscopy (SEM) of corn stem after S. obliquus cultivation exhibited substantial phloem degradation. Transcriptomic analyses of S. obliquus 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 S. obliquus at 50 L volume in mini raceway ponds to determine the scalability of this approach.

The telomere-to-telomere, gapless, phased diploid genome and methylome of the green algaScenedesmus obliquusUTEX 3031 reveals significant heterozygosity and functional separation of the haplotypes

“…Paired-end, poly-A selected RNA sequencing was performed using an Illumina NextSeq 500. Individual libraries consisted of ambient air and CO 2 supplemented grown samples at log and mid-log growth intervals for a total of 123,614,170 paired-end 150bp RNA-seq reads encompassing a diverse transcript pool (Jenna Y Schambach et al, 2022). In parallel, we combined raw RNA-seq reads from all libraries and trimmed them using fastp v0.23.2 (Chen et al, 2018).…”