Acyl-CoA binding protein is required for lipid droplet degradation in the diatom Phaeodactylum tricornutum

Advances in algal lipid metabolism and their use to improve oil content

Microalgae are eukaryotic photosynthetic micro-organisms that convert CO2 into carbohydrates, lipids, and other valuable metabolites. They are considered promising chassis for the production of various bioproducts, including fatty acid-derived biofuels. However, algae-based biofuels are not yet commercially available, mainly because of their low yields and high production cost. Optimizing strains to improve lipid productivity using the principles of synthetic biology should help move forward. This necessitates developments in the following areas: (1) identification of molecular bricks (enzymes, transcription factors, regulatory proteins etc.); (2) development of genetic tools; and (3) availability of high-throughput phenotyping methods. Here, we highlight the most recent developments in some of these areas and provide examples of the use of genome editing tools to improve oil content.

Mitochondrial alternative oxidase pathway accelerates non-motile cell germination by enhancing respiratory carbon metabolism and maintaining redox poise in Haematococcus pluvialis

Low efficiency of the cultivation process is a major obstacle in the commercial production of Haematococcus pluvialis. Germination of red, non-motile cells is an efficient strategy for rapid acquisition of zoospores. However, the regulatory mechanisms associated with germination remain unexplored. In the present study, it was confirmed that the mitochondrial alternative oxidase (AOX) pathway accelerates H. pluvialis cell germination, and the regulatory mechanisms were clarified. When the AOX pathway was inhibited, the transcriptomic and metabonomic data revealed a downregulation in respiratory carbon metabolism and nucleotide synthesis due to NADH accumulation. This observation suggested that AOX promoted the rapid consumption of NADH, which accelerated carbohydrate and lipid catabolism, thereby producing carbon skeletons for DNA replication through respiratory metabolism. Moreover, AOX could potentially enhance germination by disturbing the abscisic acid signaling pathway. These findings provide novel insights for developing industrial cultivation models based on red-cell-germination for achieving rapid proliferation of H. pluvialis.

The Clinical Promise of Microalgae in Rheumatoid Arthritis: From Natural Compounds to Recombinant Therapeutics

Rheumatoid arthritis (RA) is an invalidating chronic autoimmune disorder characterized by joint inflammation and progressive bone damage. Dietary intervention is an important component in the treatment of RA to mitigate oxidative stress, a major pathogenic driver of the disease. Alongside traditional sources of antioxidants, microalgae-a diverse group of photosynthetic prokaryotes and eukaryotes-are emerging as anti-inflammatory and immunomodulatory food supplements. Several species accumulate therapeutic metabolites-mainly lipids and pigments-which interfere in the pro-inflammatory pathways involved in RA and other chronic inflammatory conditions. The advancement of the clinical uses of microalgae requires the continuous exploration of phytoplankton biodiversity and chemodiversity, followed by the domestication of wild strains into reliable producers of said metabolites. In addition, the tractability of microalgal genomes offers unprecedented possibilities to establish photosynthetic microbes as light-driven biofactories of heterologous immunotherapeutics. Here, we review the evidence-based anti-inflammatory mechanisms of microalgal metabolites and provide a detailed coverage of the genetic engineering strategies to enhance the yields of endogenous compounds and to develop innovative bioproducts.