Diatom Milking: A Review and New Approaches

Abstract

The rise of human populations and the growth of cities contribute to the depletion of natural resources, increase their cost, and create potential climatic changes. To overcome difficulties in supplying populations and reducing the resource cost, a search for alternative pharmaceutical, nanotechnology, and energy sources has begun. Among the alternative sources, microalgae are the most promising because they use carbon dioxide (CO2) to produce biomass and/or valuable compounds. Once produced, the biomass is ordinarily harvested and processed (downstream program). Drying, grinding, and extraction steps are destructive to the microalgal biomass that then needs to be renewed. The extraction and purification processes generate organic wastes and require substantial energy inputs. Altogether, it is urgent to develop alternative downstream processes. Among the possibilities, milking invokes the concept that the extraction should not kill the algal cells. Therefore, it does not require growing the algae anew. In this review, we discuss research on milking of diatoms. The main themes are (a) development of alternative methods to extract and harvest high added value compounds; (b) design of photobioreactors; (c) biodiversity and (d) stress physiology, illustrated with original results dealing with oleaginous diatoms.

Multiplexed Knockouts in the Model Diatom Phaeodactylum by Episomal Delivery of a Selectable Cas9

“…Diatoms shunt nutrients toward metabolic processes that produce industrially valuable products such as biodiesel precursors (triglycerides a.k.a. TAGs), polyunsaturated fatty acids (PUFAs), and photosynthetic pigments (Pulz and Gross, 2004;Vinayak et al, 2015). Regardless of their innate ability to produce these high-valued molecules (HVMs), increasing production beyond their native capabilities is desirable for reducing production costs, and achieving sustainability goals in industrial agriculture applications (Gao, 2018).…”

“…Regardless of their innate ability to produce these high-valued molecules (HVMs), increasing production beyond their native capabilities is desirable for reducing production costs, and achieving sustainability goals in industrial agriculture applications (Gao, 2018). Utilization of genetic engineering technologies could shift metabolic outputs of marine diatoms toward these HVMs and improve commercial production where algae have been suggested as biological platforms for industrial feedstock and nutraceutical production (Vinayak et al, 2015). Nevertheless, the development and optimization of such genetic engineering technologies is necessary before they can be safely, easily, and robustly employed.…”

Exploring Valuable Lipids in Diatoms

“…Diatoms have attracted increasing attention for their potentials in producing a variety of bioactive compounds and fine chemicals for industrial applications (Vinayak et al, 2015). For example, diatoms are rich in pigments such as carotenoids that have been widely applied in food supplements and feeds, pharmaceutical ingredients, and cosmetics (Vilchez et al, 2011;Fu et al, 2015).…”

Microalgae with Immunomodulatory Activities

“…Several active raw extracts, fractions, and pure compounds have been identified, however, they have not reached the clinical trials yet (https://www.midwestern.edu/departments/marinepharmacology/clinical-pipeline.xml). On the contrary, microalgal extracts and compounds have already found application in the nutraceutical and cosmetical sectors [128][129][130][131][132][133][134][135].…”