Microalgal lipids: biochemistry and biotechnology

A Review of Fucoxanthin Biomanufacturing from Phaeodactylum tricornutum

Microalgae, compared to macroalgae, exhibit advantages such as rapid growth rates, feasible large-scale cultivation, and high fucoxanthin content. Among these microalgae, Phaeodactylum tricornutum emerges as an optimal source for fucoxanthin production. This paper comprehensively reviews the research progress on fucoxanthin production using Phaeodactylum tricornutum from 2012 to 2022, offering detailed insights into various aspects, including strain selection, media optimization, nutritional requirements, lighting conditions, cell harvesting techniques, extraction solvents, extraction methodologies, as well as downstream separation and purification processes. Additionally, an economic analysis is performed to assess the costs of fucoxanthin production from Phaeodactylum tricornutum, with a comparative perspective to astaxanthin production from Haematococcus pluvialis. Lastly, this paper discusses the current challenges and future opportunities in this research field, serving as a valuable resource for researchers, producers, and industry managers seeking to further advance this domain.

The Neuroprotective Role of Cyanobacteria with Focus on the Anti-Inflammatory and Antioxidant Potential: Current Status and Perspectives

Neurodegenerative diseases are linked to the process of neurodegeneration. This can be caused by several mechanisms, including inflammation and accumulation of reactive oxygen species. Despite their high incidence, there is still no effective treatment or cure for these diseases. Cyanobacteria have been seen as a possible source for new compounds with anti-inflammatory and antioxidant potential, such as polysaccharides (sacran), phycobiliproteins (phycocyanin) and lipopeptides (honaucins and malyngamides), which can be interesting to combat neurodegeneration. As a promising case of success, Arthrospira (formerly Spirulina) has revealed a high potential for preventing neurodegeneration. Additionally, advantageous culture conditions and sustainable production of cyanobacteria, which are allied to the development of genetic, metabolic, and biochemical engineering, are promising. The aim of this review is to compile and highlight research on the anti-inflammatory and antioxidant potential of cyanobacteria with focus on the application as neuroprotective agents. Also, a major goal is to address essential features that brand cyanobacteria as an ecoefficient and economically viable option, linking health to sustainability.

A Comparative Analysis Assessing Growth Dynamics of Locally Isolated Chlorella sorokiniana and Chlorella vulgaris for Biomass and Lipid Production with Biodiesel Potential

Prior research has emphasized the potential of microalgae in biodiesel production, driven by their ability to replace fossil fuels. However, the significant costs associated with microalgae cultivation present a major obstacle to scaling up production. This study aims to develop an eco-friendly microalgae cultivation system by integrating carbon dioxide from flue gas emissions with an affordable photobioreactor, providing a sustainable biomass production. The research evaluates the growth performance of Chlorella sorokiniana and Chlorella vulgaris across this integrated system for biomass and lipid production. Results indicate substantial biomass yields of 1.97 and 1.84 g/L, with lipid contents of 35 % and 41 % for C. sorokiniana and C. vulgaris, respectively. The macrobubble photobioreactor demonstrates high potential for microalgae biomass and lipid production, yielding quality fatty acid methyl esters such as palmitic, linoleic and stearic. This study presents an environmentally friendly system for efficient microalgae cultivation, generating lipid-rich biomass suitable for biodiesel production.

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.

Towards Lipid from Microalgae: Products, Biosynthesis, and Genetic Engineering

Microalgae can convert carbon dioxide into organic matter through photosynthesis. Thus, they are considered as an environment-friendly and efficient cell chassis for biologically active metabolites. Microalgal lipids are a class of organic compounds that can be used as raw materials for food, feed, cosmetics, healthcare products, bioenergy, etc., with tremendous potential for commercialization. In this review, we summarized the commercial lipid products from eukaryotic microalgae, and updated the mechanisms of lipid synthesis in microalgae. Moreover, we reviewed the enhancement of lipids, triglycerides, polyunsaturated fatty acids, pigments, and terpenes in microalgae via environmental induction and/or metabolic engineering in the past five years. Collectively, we provided a comprehensive overview of the products, biosynthesis, induced strategies and genetic engineering in microalgal lipids. Meanwhile, the outlook has been presented for the development of microalgal lipids industries, emphasizing the significance of the accurate analysis of lipid bioactivity, as well as the high-throughput screening of microalgae with specific lipids.

The metabolites of light: Untargeted metabolomic approaches bring new clues to understand light-driven acclimation of intertidal mudflat biofilm

The microphytobenthos (MPB), a microbial community of primary producers, play a key role in coastal ecosystem functioning, particularly in intertidal mudflats. These mudflats experience challenging variations of irradiance, forcing the micro-organisms to develop photoprotective mechanisms to survive and thrive in this dynamic environment. Two major adaptations to light are well described in literature: the excess of light energy dissipation through non-photochemical quenching (NPQ), and the vertical migration in the sediment. These mechanisms trigger considerable scientific interest, but the biological processes and metabolic mechanisms involved in light-driven vertical migration remain largely unknown. To our knowledge, this study investigates for the first time metabolomic responses of a migrational mudflat biofilm exposed for 30 min to a light gradient of photosynthetically active radiation (PAR) from 50 to 1000 μmol photons m-2 s-1. The untargeted metabolomic analysis allowed to identify metabolites involved in two types of responses to light irradiance levels. On the one hand, the production of SFAs and MUFAs, primarily derived from bacteria, indicates a healthy photosynthetic state of MPB under low light (LL; 50 and 100 PAR) and medium light (ML; 250 PAR) conditions. Conversely, when exposed to high light (HL; 500, 750 and 1000 PAR), the MPB experienced light-induced stress, triggering the production of alka(e)nes and fatty alcohols. The physiological and ecological roles of these compounds are poorly described in literature. This study sheds new light on the topic, as it suggests that these compounds may play a crucial and previously unexplored role in light-induced stress acclimation of migrational MPB biofilms. Since alka(e)nes are produced from FAs decarboxylation, these results thus emphasize for the first time the importance of FAs pathways in microphytobenthic biofilms acclimation to light.

Advanced Drug Carriers: A Review of Selected Protein, Polysaccharide, and Lipid Drug Delivery Platforms

Studies on bionanocomposite drug carriers are a key area in the field of active substance delivery, introducing innovative approaches to improve drug therapy. Such drug carriers play a crucial role in enhancing the bioavailability of active substances, affecting therapy efficiency and precision. The targeted delivery of drugs to the targeted sites of action and minimization of toxicity to the body is becoming possible through the use of these advanced carriers. Recent research has focused on bionanocomposite structures based on biopolymers, including lipids, polysaccharides, and proteins. This review paper is focused on the description of lipid-containing nanocomposite carriers (including liposomes, lipid emulsions, lipid nanoparticles, solid lipid nanoparticles, and nanostructured lipid carriers), polysaccharide-containing nanocomposite carriers (including alginate and cellulose), and protein-containing nanocomposite carriers (e.g., gelatin and albumin). It was demonstrated in many investigations that such carriers show the ability to load therapeutic substances efficiently and precisely control drug release. They also demonstrated desirable biocompatibility, which is a promising sign for their potential application in drug therapy. The development of bionanocomposite drug carriers indicates a novel approach to improving drug delivery processes, which has the potential to contribute to significant advances in the field of pharmacology, improving therapeutic efficacy while minimizing side effects.

Employing Genome Mining to Unveil a Potential Contribution of Endophytic Bacteria to Antimicrobial Compounds in the Origanum vulgare L. Essential Oil

Essential oils (EOs) from medicinal plants have long been used in traditional medicine for their widely known antimicrobial properties and represent a promising reservoir of bioactive compounds against multidrug-resistant pathogens. Endophytes may contribute to the yield and composition of EOs, representing a useful tool for biotechnological applications. In this work, we investigated the genomic basis of this potential contribution. The annotated genomes of four endophytic strains isolated from Origanum vulgare L. were used to obtain KEGG ortholog codes, which were used for the annotation of different pathways in KEGG, and to evaluate whether endophytes might harbor the (complete) gene sets for terpene and/or plant hormone biosynthesis. All strains possessed ortholog genes for the mevalonate-independent pathway (MEP/DOXP), allowing for the production of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) precursors. Ortholog genes for the next steps in terpenoid biosynthesis were scarce. All the strains possess potential plant growth promotion (PGP) ability, as shown by the presence of orthologous genes involved in the biosynthesis of indoleacetic acid. The main contribution of endophytes to the yield and composition of O. vulgare EO very likely resides in their PGP activities and in the biosynthesis of precursors of bioactive compounds.

Auxin supplementation under nitrogen limitation enhanced oleic acid and MUFA content in Eustigmatos calaminaris biomass with potential for biodiesel production

Due to their lipid accumulation potential, microalgae are widely studied in terms of their use in the production of biodiesel. The present study was focused on determination of changes in the biomass production, biochemical composition, accumulation and distribution of fatty acids in neutral lipids, glycolipids, phospholipids and biodiesel properties of soil microalga Eustigmatos calaminaris in response to various levels of nitrogen stress and indole-3-acetic acid supplementation. The highest growth rate, the highest lipid content and daily lipid productivity were noted at the nitrogen limitation up to 25% with IAA supplementation. The increase in NL was associated with nutrient stress. An increase in the level of GL and PL were recorded upon the reduction of the nitrogen content (25% N) and the addition of IAA. The gas chromatography/mass spectrometry analysis demonstrated that C16:0, C16:1, and C18:1 were the main fatty acids in E. calaminaris lipids. As shown by the lipidomic analysis, the IAA supplementation in the nitrogen limitation variants enhanced the content of TAGs in C18:1 and monounsaturated fatty acids. The current findings indicated a potential strategy to improve the fatty acid profile in neutral lipids and high potential of E. calaminaris for biodiesel applications.

Identification and Functional Analysis of Acyl-Acyl Carrier Protein Δ9 Desaturase from Nannochloropsis oceanica

The oleaginous marine microalga Nannochloropsis oceanica strain IMET1 has attracted increasing attention as a promising photosynthetic cell factory due to its unique excellent capacity to accumulate large amounts of triacylglycerols and eicosapentaenoic acid. To complete the genomic annotation for genes in the fatty acid biosynthesis pathway of N. oceanica, we conducted the present study to identify a novel candidate gene encoding the archetypical chloroplast stromal acyl-acyl carrier protein Δ⁹ desaturase. The full-length cDNA was generated using rapid-amplification of cDNA ends, and the structure of the coding region interrupted by four introns was determined. The RT-qPCR results demonstrated the upregulated transcriptional abundance of this gene under nitrogen starvation condition. Fluorescence localization studies using EGFP-fused protein revealed that the translated protein was localized in chloroplast stroma. The catalytic activity of the translated protein was characterized by inducible expression in Escherichia coli and a mutant yeast strain BY4389, indicating its potential desaturated capacity for palmitoyl-ACP (C16:0-ACP) and stearoyl-ACP (C18:0-ACP). Further functional complementation assay using BY4839 on plate demonstrated that the expressed enzyme restored the biosynthesis of oleic acid. These results support the desaturated activity of the expressed protein in chloroplast stroma to fulfill the biosynthesis and accumulation of monounsaturated fatty acids in N. oceanica strain IMET1.