Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts

Abstract

In 2010, when the National Alliance for Advanced Biofuels and Bioproducts (NAABB) consortium began, little was known about the molecular basis of algal biomass or oil production. Very few algal genome sequences were available and efforts to identify the best-producing wild species through bioprospecting approaches had largely stalled after the U.S. Department of Energy's Aquatic Species Program. This lack of knowledge included how reduced carbon was partitioned into storage products like triglycerides or starch and the role played by metabolite remodeling in the accumulation of energy-dense storage products. Furthermore, genetic transformation and metabolic engineering approaches to improve algal biomass and oil yields were in their infancy. Genome sequencing and transcriptional profiling were becoming less expensive, however; and the tools to annotate gene expression profiles under various growth and engineered conditions were just starting to be developed for algae. It was in this context that an integrated algal biology program was introduced in the NAABB to address the greatest constraints limiting algal biomass yield. This review describes the NAABB algal biology program, including hypotheses, research objectives, and strategies to move algal biology research into the twenty-first century and to realize the greatest potential of algae biomass systems to produce biofuels.

Microalgae community shifts during the biogas upgrading in an alkaline open photobioreactor

“…Under continuous illumination the CO 2 fixation capacities of the alkali‐tolerant microalgae consortium are slightly lower than those described by Unkefer et al . () for some of the individual microalgae strains here identified, the reported values are between 550–1000 mg CO 2 l −1 per day which would indicate that other nonidentified members of the alkali‐tolerant microalgae consortium had lower CO 2 fixation capabilities or the consortium had unfavourable interactions among their members.…”

“…whose integrants have showed particular activities in CO 2 fixation processes (Unkefer et al . ). The Rr indicated an inverse correlation between richness and CO 2 fixation rates under continuous illumination, Rr decreased when the open photobioreactor was supplied with synthetic biogas, as explained below.…”

The Colonial Microalgae Botryococcus braunii as Biorefinery

“…The acyl-CoA reductase and decarbonylase enzymes in race A microsomes suggest an alternative mechanism where the LCFAs are reduced to aldehydes and decarbonylated to produce alkadienes and alkatrienes [17,30]. Race A transcriptome allowed the identification of six candidate genes potentially involved in this biosynthesis [31].…”

“…Expressed sequence tag (EST) markers for enzymes of the DXP/MEP pathway [34], as well as multiple isoforms of enzymes for the 3-phospho-D-glycerate biosynthesis from D-glyceraldehyde-3phosphate and pyruvate as precursors, were identified. Some of the respective transcripts are present in high abundance (>250 reads/Kb), suggesting a high metabolic flow in B. braunii [31].…”

Transcriptomic responses associated with carbon and energy flows under high salinity stress suggest the overflow of acetyl-CoA from glycolysis and NADPH co-factor induces high lipid accumulation and halotolerance inChlorellasp. HS2

“…Microalgae exhibit a greater biomass yield than most terrestrial crops and can be grown with excess nutrients in wastewater sources, prompting its industrial utilization as a biofeedstock for the production of nutraceuticals, pharmaceuticals, cosmetics, and biofuels (Hu et al, 2008; Quinn & Davis, 2015; Smith, Sturm, Denoyelles, & Billings, 2010; Unkefer et al, 2017; Yun, Cho, Lee, Heo, et al, 2018). However, commercial production of algal biomass is not yet considered to be economically competitive because of high energy inputs associated with biomass harvesting and downstream extraction of desirable biomolecules (Laurens et al, 2017; Stephens et al, 2010; Valizadeh Derakhshan, Nasernejad, Abbaspour-Aghdam, & Hamidi, 2015).…”