Development of a high-productivity, halophilic, thermotolerant microalga Picochlorum renovo

Abstract

Microalgae are promising biocatalysts for applications in sustainable fuel, food, and chemical production. Here, we describe culture collection screening, down-selection, and development of a high-productivity, halophilic, thermotolerant microalga, Picochlorum renovo. This microalga displays a rapid growth rate and high diel biomass productivity (34 g m−2 day−1), with a composition well-suited for downstream processing. P. renovo exhibits broad salinity tolerance (growth at 107.5 g L−1 salinity) and thermotolerance (growth up to 40 °C), beneficial traits for outdoor cultivation. We report complete genome sequencing and analysis, and genetic tool development suitable for expression of transgenes inserted into the nuclear or chloroplast genomes. We further evaluate mechanisms of halotolerance via comparative transcriptomics, identifying novel genes differentially regulated in response to high salinity cultivation. These findings will enable basic science inquiries into control mechanisms governing Picochlorum biology and lay the foundation for development of a microalga with industrially relevant traits as a model photobiology platform.

A multi-omic characterization of temperature stress in a halotolerant Scenedesmus strain for algal biotechnology

“…Presence of Pfam domains were investigated in the NREL 46B-D3 genome and compared to other Chlorophyta genomes. There were 3,200 distinct Pfam domains identified in the NREL 46B-D3 genome (7,304 out of 17,399 genes were annotated with at least one Pfam domain), which is slightly fewer to the number found in the S. obliquus UTEX 3031 genome (3,363 distinct Pfam domains) and in UTEX 393 (3,520). Five Pfam domains were only found in the NREL 46B-D3 genome and missing in all other Chlorophyceae genomes analyzed.…”

“…With an estimated 1 million species 2 , algae are diverse in habitat and metabolic output yet the individual identification, characterization, and development of more resilient and productive strains is essential to achieving economically viable mass cultivation. While bioprospecting and strain screening have proven to be an effective approach to acquiring increasingly better performing taxa [3][4][5] , the time and resources required to assess growth physiology, metabolite production, and robustness to environmental stressors create a bottleneck. To this end, we have recently established a screening and characterization pipeline using simulated outdoor deployment screening methodology, as described previously 3,4 .…”

“…While bioprospecting and strain screening have proven to be an effective approach to acquiring increasingly better performing taxa [3][4][5] , the time and resources required to assess growth physiology, metabolite production, and robustness to environmental stressors create a bottleneck. To this end, we have recently established a screening and characterization pipeline using simulated outdoor deployment screening methodology, as described previously 3,4 . Top-candidates emerging from this pipeline are evaluated for growth rate, biomass accumulation, halotolerance, and carbon storage capacity.…”

CO2 process intensification of algae oil extraction to biodiesel

“…To realize a dream of making algal biofuels a reality, efforts are being directed to reduce the biomass production costs. In recent research, published in October 2019, NREL researchers developed through genetic manipulation a high productivity (34 g‐m −2 d −1 ) microalga strain, Picochlorum renova , which displays a rapid growth rate, salinity tolerance, and thermotolerance; traits that are best suited for outdoor cultivation 56 . Clearly, further experiments and validations of their results from outdoor studies can confirm the actual biomass yield.…”

Inhibition of DNA Methylation in Picochlorum soloecismus Alters Algae Productivity

“…A recent algae biofuel consortium (the National Alliance for Advanced Biofuels and Bioproducts) denoted P. soloecismus as a promising feedstock for biofuel research (Unkefer et al, 2017). The Picochlorum genus is highly adaptive to environmental variation in salinity, temperature, pH, and nutrients; it readily alters its gene expression as such to induce particular phenotypes under these various conditions (Foflonker et al, 2015;Krasovec et al, 2018;Dahlin et al, 2019;Gonzalez-Esquer et al, 2019;Steadman Tyler et al, 2019). Bioengineering P. soloecismus includes the manipulation of gene expression to mimic environmental conditions that drive carbon sequestration, but efforts have been limited.…”