Phaeodactylum tricornutum: A Diatom Cell Factory

P. tricornutum CCAP 1055/1 is a diatom with a sequenced annotated genome with >100 000 expression sequence tags. Transformation is becoming routine using biolistics, electroporation, and more recently by conjugation with E. coli. There is improved understanding of its biochemical pathways. P. tricornutum is showcased as a microalgal cell factory with a product spectrum including eicosapentaenoic acid, fucoxanthin, neutral lipids, and crysolaminarin, all producible with the chassis, in addition to heterologous recombinant proteins, triterpenoids (lupeol and betulin), and bioplastics precursors. P. tricornutum can be readily harvested with a host of approaches, and relevant products can be recovered using green extraction processes such as microwave-assisted and pressurized liquid extraction, with the potential to develop sustainable cost-effective processes in a biorefinery approach. A switch from a petroleum-based to a biobased economy requires the capacity to produce both high-value low-volume and low-value high-volume products. Recent evidence supports the development of microalgae-based microbial cell factories with the objective of establishing environmentally sustainable manufacturing solutions. Diatoms display rich diversity and potential in this regard. We focus on Phaeodactylum tricornutum, a pennate diatom that is commonly found in marine ecosystems, and discuss recent trends in developing the diatom chassis for the production of a suite of natural and genetically engineered products. Both upstream and downstream developments are reviewed for the commercial development of P. tricornutum as a cell factory for a spectrum of marketable products. A switch from a petroleum-based to a biobased economy requires the capacity to produce both high-value low-volume and low-value high-volume products. Recent evidence supports the development of microalgae-based microbial cell factories with the objective of establishing environmentally sustainable manufacturing solutions. Diatoms display rich diversity and potential in this regard. We focus on Phaeodactylum tricornutum, a pennate diatom that is commonly found in marine ecosystems, and discuss recent trends in developing the diatom chassis for the production of a suite of natural and genetically engineered products. Both upstream and downstream developments are reviewed for the commercial development of P. tricornutum as a cell factory for a spectrum of marketable products. a method to gain insights into the fundamentals of molecular evolution and adaptive changes that occur in populations during long-term selection under specific growth conditions. An organism is repeatedly cultured by exposure to predefined conditions to accelerate evolution in the laboratory. also known as allelic bias, where one allele is expressed at levels higher than the other. where biological feedstock and/or bioprocesses are employed to derive products of value for economic gain as sustainable solutions to the challenges we face (food, energy, chemicals, health, materials, and environmental protection). a process that aims to replace oil with biomass as a feedstock for fuel and chemical production through the integration of green chemistry and sustainable production. The aim is to produce multiple products from biomass to add value to the process (in a way akin to a chemical refinery). a cell host or an organism with a genome that can be altered to maintain heterologous DNA components for gene expression. steps downstream of cultivation that are employed to recover products of interest; these can encompass cell harvesting and the extraction of products of interest from natural sources followed by product purification or formulation. tools used to inactivate specific genes of an organism. These are usually developed to study gene function and to investigate the phenotype produced by gene loss. targets precise sites within a genome by introducing double-strand breaks into a specific guided site that is then repaired, resulting in a modest deletion of a few nucleotides of the native gene. Insertional activation through incorporation of a non-native gene encoding a selectable marker is not required. assembly methods used across the synthetic biology community which employ a 'one-pot/tube' method and do not rely on restriction sites. Gibson assembly involves long-overlap assembly (exonuclease for annealing fragments, polymerase for filling the gaps, and DNA ligase for sealing the nicks in the assembled DNA) where multiple parts can be assembled (promoters, terminators, and other short sequences). Golden Gate is based on type II S restriction endonucleases which cleave double-stranded DNA outside their recognition sites, generating short single-stranded overhangs; Bsal restriction sites are utilized for simultaneous digestion and ligation, thus preventing religation. a mode of cultivation where the culture uses both carbon dioxide and organic carbon supplemented in the nutrient medium as carbon sources. an organism that can make energy from sunlight and carbon dioxide through photosynthesis to synthesize organic compounds for growth. a subcellular compartment in the chloroplast of most algae that is associated with the carbon-concentrating mechanism (augments photosynthetic productivity by increasing inorganic carbon). events that occur when a living cell engulfed another eukaryotic cell that had undertaken primary endosymbiosis, resulting in a cell with a double phospholipid bilayer around both the mitochondria and chloroplasts. sequences that determine a specific set of traits that provide the transformed cells with different properties from untransformed cells. Selection markers can affect the conditions under which the transformed cell can grow, for example antibiotic-resistant transformed cells can grow in medium containing antibiotics. also known as a jumping gene, a DNA sequence that can alter its position within a genome, occasionally resulting in a reverse mutation and altering the genetics and genome size of the host cell.