Fucoxanthin Production Research Articles

Machine learning-based prediction models unleash the enhanced production of fucoxanthin in Isochrysis galbana.

The marine microalga Isochrysis galbana is prolific producer of fucoxanthin, which is a xanthophyll carotenoid with substantial global market value boasting extensive applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. This study presented a novel integrated experimental approach coupled with machine learning (ML) models to predict the fucoxanthin content in I. galbana by altering the type and concentration of phytohormone supplementation, thus overcoming the multiple methodological limitations of conventional fucoxanthin quantification. A novel integrated experimental approach was developed, analyzing the effect of varying phytohormone types and concentrations on fucoxanthin production in I. galbana. Morphological analysis was conducted to assess changes in microalgal structure, while growth rate and fucoxanthin yield correlations were explored using statistical analysis and machine learning models. Several ML models were employed to predict fucoxanthin content, with and without hormone descriptors as variables. The findings revealed that the Random Forest (RF) model was highly significant with a high of 0.809 and of 0.776 when hormone descriptors were excluded, and the inclusion of hormone descriptors further improved prediction accuracy to of 0.839, making it a useful tool for predicting the fucoxanthin yield. The model that fitted the experimental data indicated methyl jasmonate (0.2 mg/L) as an effective phytohormone. The combined experimental and ML approach demonstrated rapid, reliable, and cost-efficient prediction of fucoxanthin yield. This study highlights the potential of machine learning models, particularly Random Forest, to optimize parameters influencing microalgal growth and fucoxanthin production. This approach offers a more efficient alternative to conventional methods, providing valuable insights into improving fucoxanthin production in microalgal cultivation. The findings suggest that leveraging diverse ML models can enhance the predictability and efficiency of fucoxanthin production, making it a promising tool for industrial applications.

Optimizing tomato waste hydrolysate for enhanced fucoxanthin biosynthesis in mixotrophic cultivation of Isochrysis galbana

Vegetable waste, rich in bioactive compounds, offers a promising resource for producing value-added products. This study explored the use of tomato waste, containing glucose (40 mg/g), lycopene (95.12 μg/g), and β-carotene (24.31 μg/g), for cultivating fucoxanthin-rich Isochrysis galbana. Water-soluble lycopene (2.0 μg/mL) and β-carotene (0.4 μg/mL) effectively upregulated key carotenoid synthesis genes and boosted cell growth and fucoxanthin production (3.64 and 3.60 pg/cell, respectively) within 10 days in a mixotrophic culture. Optimized tomato waste hydrolysate achieved a high cell density of 1.21 × 107 cells/mL, 2.13 g/L biomass, and 21.02 mg/g fucoxanthin. This study highlights the potential of combining tomato waste with microalgae for a novel and innovative approach towards waste management and resource utilization.

Nutritional Value and Productivity Potential of the Marine Microalgae Nitzschia laevis, Phaeodactylum tricornutum and Isochrysis galbana.

Microalgae are considered promising sustainable feedstocks for the production of food, food additives, feeds, chemicals and various high-value products. Marine microalgae Phaeodactylum tricornutum, Isochrysis galbana and Nitzschia laevis are rich in fucoxanthin, which is effective for weight loss and metabolic diseases. The selection of microalgae species with outstanding nutritional profiles is fundamental for novel foods development, and the nutritional value of P. tricornutum, I. galbana and N. laevis are not yet fully understood. Hence, this study investigates and analyzes the nutritional components of the microalgae by chromatography and mass spectrometry, to explore their nutritional and industrial application potential. The results indicate that the three microalgae possess high nutritional value. Among them, P. tricornutum shows significantly higher levels of proteins (43.29%) and amino acids, while I. galbana has the highest content of carbohydrates (25.40%) and lipids (10.95%). Notwithstanding that P. tricornutum and I. galbana have higher fucoxanthin contents, N. laevis achieves the highest fucoxanthin productivity (6.21 mg/L/day) and polyunsaturated fatty acids (PUFAs) productivity (26.13 mg/L/day) because of the competitive cell density (2.89 g/L) and the advantageous specific growth rate (0.42/day). Thus, compared with P. tricornutum and I. galbana, N. laevis is a more promising candidate for co-production of fucoxanthin and PUFAs.

Production of Fucoxanthin from Microalgae Isochrysis galbana of Djibouti: Optimization, Correlation with Antioxidant Potential, and Bioinformatics Approaches.

Fucoxanthin, a carotenoid with remarkable antioxidant properties, has considerable potential for high-value biotechnological applications in the pharmaceutical, nutraceutical, and cosmeceutical fields. However, conventional extraction methods of this molecule from microalgae are limited in terms of cost-effectiveness. This study focused on optimizing biomass and fucoxanthin production from Isochrysis galbana, isolated from the coast of Tadjoura (Djibouti), by testing various culture media. The antioxidant potential of the cultures was evaluated based on the concentrations of fucoxanthin, carotenoids, and total phenols. Different nutrient formulations were tested to determine the optimal combination for a maximum biomass yield. Using the statistical methodology of principal component analysis, Walne and Guillard F/2 media were identified as the most promising, reaching a maximum fucoxanthin yield of 7.8 mg/g. Multiple regression models showed a strong correlation between antioxidant activity and the concentration of fucoxanthin produced. A thorough study of the optimization of I. galbana growth conditions, using a design of experiments, revealed that air flow rate and CO2 flow rate were the most influential factors on fucoxanthin production, reaching a value of 13.4 mg/g. Finally, to validate the antioxidant potential of fucoxanthin, an in silico analysis based on molecular docking was performed, showing that fucoxanthin interacts with antioxidant proteins (3FS1, 3L2C, and 8BBK). This research not only confirmed the positive results of I. galbana cultivation in terms of antioxidant activity, but also provided essential information for the optimization of fucoxanthin production, opening up promising prospects for industrial applications and future research.

Development of a cost-effective medium suitable for the growth and fucoxanthin production of the microalgae Odontella aurita using jeju lava seawater and agricultural fertilizers

Diatoms have garnered significant attention in various industries, including feed, food, and pharmaceuticals, due to their potential as advanced biomaterials containing valuable components such as fatty acids, pigments, and nanoparticles. However, the industrial-scale cultivation of diatoms has faced challenges such as limited productivity and high production costs. This study aimed to develop a cost-effective growth medium for the cultivation of Odontella aurita, a diatom known for its high levels of fatty acids and fucoxanthin production. The research investigated the impact of Jeju lava seawater on the growth of O. aurita OAOSH22 and evaluated the effectiveness of five different agricultural fertilizers in cultivation. The final composition included the selected fertilizer supplemented with silicate. The growth of O. aurita in F/2 medium supplemented with Jeju lava seawater was found to be 1.8 times higher than in the ordinary seawater-based F/2 medium, attributed to the elevated silicon content in Jeju lava seawater. The optimized medium, incorporating Jeju lava seawater and agricultural fertilizer, resulted in a significant increase in biomass by a factor of 15.6 and a substantial rise in fucoxanthin production by a factor of 7.5. Additionally, the utilization of this optimized medium resulted in a significant reduction of 95.1 % and 89.7 % in the costs associated with biomass and fucoxanthin production, respectively. These findings suggest that the use of Jeju lava seawater promotes the growth of O. aurita, and the optimized medium, including agricultural fertilizers, provides a cost-effective alternative to existing microalgal media.

Analysis of Amphora ostrearia var. minor Grunow, a blooming marine diatom (Bacillariophyceae) in French Atlantic coastal waters and its transfer to the genus Tetramphora

A marine amphoroid diatom, responsible for blooms in 2011 and 2019 in French Atlantic waters was studied using morphology and molecular phylogeny. The highest cell concentrations were reached in the region of Marennes Oléron on 19 August 2011 and were related to a greyish discolouration of gills of oysters and mussels. It was identified as Amphora ostrearia var. minor Grunow, based on morphological characteristics. To ensure the correct identification, type material was re-investigated, using the type slide n° 142 (Cleve & Möller 1878. Diatoms. Part II. Esatas Edquists Boktryckeri, Upsala: 49–108) that enabled us to establish the identity of the taxon. Plastid morphology corresponded to Mereschkowsky’s type 8 amphoroid chloroplast, a feature typical for the genus Tetramphora Mereschkowsky. Results of a phylogenetic analysis inferred from a concatenated alignment including the nuclear marker SSU and the chloroplast rbcL indicated that A. ostrearia var. minor was positioned inside the monophyletic clade Tetramphora (Mereschkowsky) Stepanek & Kociolek. This, together with the morphological data, necessitated a transfer of A. ostrearia var. minor Grunow to the genus Tetramphora (Mereschkowsky) Stepanek & Kociolek. In addition, the genetic distances (p-values) from SSU–rbcL sequences were estimated among the species of Tetramphora including T. ostrearia, the generitype. These revealed that the divergence between Tetramphora ostrearia (Brébisson) Mereschkowsky and its variety minor was higher than the mean value within species of the genus. As a consequence, the studied taxon is raised to the species level as Tetramphora minor (Grunow) Nézan, comb. et stat. nov. Toxin analysis of four strains of T. minor revealed the absence of domoic acid production. Pigment analysis of T. ostrearia revealed a high fucoxanthin production, similar to other amphoroid species.

Alternative production of fucoxanthin and PUFAs using Chlorochromonas danica and Hibberdia magna, unicellular chrysophytes with different trophic modes

Ochrophyte microalgae attract attention from the applied phycology perspective, due to their ability to grow rapidly, engage variable trophic modes, and simultaneously produce high-value compounds such as xanthophyll carotenoids and polyunsaturated fatty acids. Unlike more often considered marine diatoms and haptophytes, unicellular chrysophytes may represent a reasonable freshwater alternative. In this work, we introduced two representatives: Chlorochromonas danica (Ochromonadales) and Hibberdia magna (Hibberdiales). We compared their ability to produce target compounds in mixotrophic and photoautotrophic modes, respectively. Both organisms had a similar temperature optima (18–22 °C), but light demands were much higher in the photoautotrophic H. magna. This work is the first report of fucoxanthin content and productivity by C. danica, showing that the presence of light enhanced the content of fucoxanthin 4.5-fold compared with darkness. For fucoxanthin productivity in the mixotrophic batch cultured C. danica, the optimal initial glucose dose was 10 g L−1. Culture medium supplemented with mineral nutrients resulted in an increase in biomass and fucoxanthin productivity of C. danica achieving the highest biomass productivity of 0.81 ± 0.06 g L−1 d−1. H. magna accumulated a maximum of 4.54 ± 0.04 mg g−1 DW of fucoxanthin, which was slightly more than the maximum value for C. danica of 3.99 ± 0.19 mg g−1 DW. However, due to the lower biomass productivity of H. magna, the maximal fucoxanthin productivities reached very similar values of 1.15 ± 0.05 and 1.16 ± 0.01 mg L d−1 in C. danica and H. magna, respectively. Both organisms had a relatively high fatty acid content, accounting for 17 % and 19 % of DW in C. danica and H. magna, respectively. H. magna had a higher level of polyunsaturated fatty acids, which were more diverse, longer, and more unsaturated. The potential for utilization of selected chrysophytes as producers in a multi-target biorefinery is discussed.

Light and Nutrient Conditions Influence Fucoxanthin Production of the Microalgae Cyclotella meneghiniana

Fucoxanthin has attracted the attention of scholars because of its health benefits in terms of anticancer, weight loss, antidiabetic, hypolipidemic, and antioxidant functions. Researchers have found that the fucoxanthin content of microalgae was higher than that of macroalgae. Therefore, the microalgae Cyclotella meneghiniana was isolated and maintained under varying light and modified nutrient conditions. The results of this study showed that Cyclotella meneghiniana had better photosynthetic activity and higher biomass under low light. Both high trace elements and high nitrogen promoted the accumulation of fucoxanthin in Cyclotella meneghiniana. Low light levels and high trace metal contents enhanced the fucoxanthin production (7.76 ± 0.30 mg g−1 DW). The results of the current study will help to enhance fucoxanthin production for commercialization.

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.

Mixotrophic culture enhances fucoxanthin production in the haptophyte Pavlova gyrans

Fucoxanthin is a versatile substance in the food and pharmaceutical industries owing to its excellent antioxidant and anti-obesity properties. Several microalgae, including the haptophyte Pavlova spp., can produce fucoxanthin and are potential industrial fucoxanthin producers, as they lack rigid cell walls, which facilitates fucoxanthin extraction. However, the commercial application of Pavlova spp. is limited owing to insufficient biomass production. In this study, we aimed to develop a mixotrophic cultivation method to increase biomass and fucoxanthin production in Pavlova gyrans OPMS 30543X. The effects of culturing OPMS 30543X with different organic carbon sources, glycerol concentrations, mixed-nutrient conditions, and light intensities on the consumption of organic carbon sources, biomass production, and fucoxanthin accumulation were analyzed. Several organic carbon sources, such as glycerol, glucose, sucrose, and acetate, were examined, revealing that glycerol was well-consumed by the microalgae. Biomass and fucoxanthin production by OPMS 30543X increased in the presence of 10 mM glycerol compared to that observed without glycerol. Metabolomic analysis revealed higher levels of the metabolites related to the glycolytic, Calvin–Benson–Bassham, and tricarboxylic acid cycles under mixotrophic conditions than under autotrophic conditions. Cultures grown under mixotrophic conditions with a light intensity of 100 µmol photons m−2 s−1 produced more fucoxanthin than autotrophic cultures. Notably, the amount of fucoxanthin produced (18.9 mg/L) was the highest reported thus far for Pavlova species. In conclusion, the use of mixotrophic culture is a promising strategy for increasing fucoxanthin production in Pavlova species.Key points• Glycerol enhances biomass and fucoxanthin production in Pavlova gyrans• Metabolite levels increase under mixotrophic conditions• Mixotrophic conditions and medium-light intensity are appropriate for P. gyrans

The role of cis-zeatin in enhancing high-temperature resistance and fucoxanthin biosynthesis in Phaeodactylum tricornutum.

Phaeodactylum tricornutum a prominent source of industrial fucoxanthin production, faces challenges in its application due to its tolerance to high-temperature environments. This study investigates the physiological responses of P. tricornutum to high-temperature stress and its impact on fucoxanthin content, with a specific focus on the role of cis-zeatin. The results reveal that high-temperature stress inhibits P. tricornutum's growth and photosynthetic activity, leading to a decrease in fucoxanthin content. Transcriptome analysis shows that high temperature suppresses the expression of genes related to photosynthesis (e.g., psbO, psbQ, and OEC) and fucoxanthin biosynthesis (e.g., PYS, PDS1, and PSD2), underscoring the negative effects of high temperature on P. tricornutum. Interestingly, genes associated with cis-zeatin biosynthesis and cytokinesis signaling pathways exhibited increased expression under high-temperature conditions, indicating a potential role of cis-zeatin signaling in response to elevated temperatures. Content measurements confirm that high temperature enhances cis-zeatin content. Furthermore, the exogenous addition of cytokinesis mimetics or inhibitors significantly affected P. tricornutum's high-temperature resistance. Overexpression of the cis-zeatin biosynthetic enzyme gene tRNA DMATase enhanced P. tricornutum's resistance to high-temperature stress, while genetic knockout of tRNA DMATase reduced its resistance to high temperatures. Therefore, this research not only uncovers a novel mechanism for high-temperature resistance in P. tricornutum but also offers a possible alga species that can withstand high temperatures for the industrial production of fucoxanthin, offering valuable insights for practical utilization.IMPORTANCEThis study delves into Phaeodactylum tricornutum's response to high-temperature stress, specifically focusing on cis-zeatin. We uncover inhibited growth, reduced fucoxanthin, and significant cis-zeatin-related gene expression under high temperatures, highlighting potential signaling mechanisms. Crucially, genetic engineering and exogenous addition experiments confirm that the change in cis-zeatin levels could influence P. tricornutum's resistance to high-temperature stress. This breakthrough deepens our understanding of microalgae adaptation to high temperatures and offers an innovative angle for industrial fucoxanthin production. This research is a pivotal step toward developing heat-resistant microalgae for industrial use.

Enhancing fucoxanthin production in Chaetoceros calcitrans under mixotrophic condition and LED wavelength shift strategy

This study addresses the challenge of achieving high fucoxanthin (Fx) productivity in Chaetoceros calcitrans under mixotrophic cultivation which often struggle to simultaneously increase biomass and Fx content. To overcome this, we investigated the potential of C. calcitrans for Fx production under mixotrophic conditions by investigating the interaction of organic carbon, light intensity, and light emitting diode (LED) color shifts during cultivation to optimize Fx production. Results revealed significant influences of various organic carbon sources on Fx productivity, with glycerol and glucose showing promising outcomes. Furthermore, the addition of external urea enhanced Fx content in mixotrophic cultivation. Response Surface Methodology (RSM) analysis highlighted the synergistic effect of light intensity and glycerol addition on Fx productivity. Most notably, shifting from white to blue LED during mixotrophic cultivation at the end of the exponential phase significantly increased Fx productivity in C. calcitrans to 3.2 mg L−1 d−1, representing a 1.3-fold enhancement compared to white LED sources. These findings underscore the potential of mixotrophic cultivation and LED color shifts as effective strategies for improving Fx productivity in diatoms.

Optimizing cultivation strategies and scaling up for fucoxanthin production using Pavlova sp.

The microalgal-based production of fucoxanthin has emerged as an imperative research endeavor due to its antioxidant, and anticancer properties. In this study, three brown marine microalgae, namely Skeletonema costatum, Chaetoceros gracilis, and Pavlova sp., were screened for fucoxanthin production. All strains displayed promising results, with Pavlova sp. exhibiting the highest fucoxanthin content (27.91 mg/g) and productivity (1.16 mg/L·day). Moreover, the influence of various cultivation parameters, such as culture media, salinity, sodium nitrate concentration, inoculum size, light intensity, and iron concentration, were investigated and optimized, resulting in a maximum fucoxanthin productivity of 7.89 mg/L·day. The investigation was further expanded to large-scale outdoor cultivation using 50 L tubular photobioreactors, illustrating the potential of Pavlova sp. and the cultivation process for future commercialization. The biomass and fucoxanthin productivity for the large-scale cultivation were 70.7 mg/L·day and 4.78 mg/L·day, respectively. Overall, the findings demonstrated considerable opportunities for fucoxanthin synthesis via microalgae cultivation and processing.

Progress on the biological characteristics and physiological activities of fucoxanthin produced by marine microalgae

BackgroundFucoxanthin is a carotenoid found in seaweed. Its unique chemical structure gives it a variety of properties. Thus fucoxanthin have attracted the attention of companies and researchers.MethodsScientific papers were collected from the database. Duplicates and unavailable literature were excluded first. Then the remaining literature was categorized for referencing in the review.ResultsThis article contains a summary of the microalgae species producing fucoxanthin and their progress in breeding and cultivation modes. Additionally, the review summarized the progress of research on physiological activities and organized the experimental models used in these studies.ConclusionsThese present findings may provide information for the upstream production of fucoxanthin from algal species selection to process optimization. The analysis of the physiological activity results will help advance subsequent physiological and biochemical experiments. Furthermore, it intends to pique researchers’ enthusiasm for fucoxanthin and enrich related research data to accelerate the development of this natural product.

Effect of Iron Concentration on the Co-Production of Fucoxanthin and Fatty Acids in Conticribra weissflogii.

The production of fucoxanthin and fatty acids in Conticribra weissflogii has been examined, but there is still a lack of understanding regarding the impact of trace elements, including iron, on their co-production. To address this knowledge gap, this study investigated the effects of FeCl3·6H2O on the growth, fucoxanthin, and fatty acids of C. weissflogii. The findings revealed that the highest cell density (1.9 × 106 cells mL-1), cell dry weight (0.89 ± 0.15 g L-1), and total fatty acid concentration (83,318.13 µg g-1) were achieved at an iron concentration of 15.75 mg L-1, while the maximum carotenoid and fucoxanthin contents were obtained at an iron concentration of 3.15 mg L-1. The study demonstrated that the content of the active substance in C. weissflogii could be increased by adjusting the iron concentration, providing new information as to the more efficient co-production of fucoxanthin and fatty acids and offering experimental support for large-scale production.

Understanding the Impact of Nitrogen Availability: A Limiting Factor for Enhancing Fucoxanthin Productivity in Microalgae Cultivation.

This study aimed to investigate the regulation of fucoxanthin (FX) biosynthesis under various nitrogen conditions to optimize FX productivity in Phaeodactylum tricornutum. Apart from light, nitrogen availability significantly affects the FX production of microalgae; however, the underlying mechanism remains unclear. In batch culture, P. tricornutum was cultivated with normal (NN, 0.882 mM sodium nitrate), limited (LN, 0.22 mM), and high (HN, 8.82 mM) initial nitrogen concentrations in f/2 medium. Microalgal growth and photosynthetic pigment production were examined, and day 5 samples were subjected to fucoxanthin-chlorophyll a/c-binding protein (FCP) proteomic and transcriptomic analyses. The result demonstrated that HN promoted FX productivity by extending the exponential growth phase for higher biomass and FX accumulation stage (P1), showing a continuous increase in FX accumulation on day 6. Augmented FX biosynthesis via the upregulation of carotenogenesis could be primarily attributed to enhanced FCP formation in the thylakoid membrane. Key proteins, such as LHC3/4, LHCF8, LHCF5, and LHCF10, and key genes, such as PtPSY, PtPDS, and PtVDE, were upregulated under nitrogen repletion. Finally, the combination of low light and HN prolonged the P1 stage to day 10, resulting in maximal FX productivity to 9.82 ± 0.56 mg/L/day, demonstrating an effective strategy for enhancing FX production in microalgae cultivation.

Phaeodactylum tricornutum as a stable platform for pilot scale production and investigation of the viability of spirulina fucoxanthin as a commercial lipolysis active novel compound

The nutraceutical market has experienced a significant growth over the last years, due to changing consumer preferences towards products of natural and organic origin. One of the main areas of interest in this field is microalgae-derived carotenoids, whose antioxidant activity protects against oxidative damage in human cells. The diatom Phaeodactylum tricornutum has been widely studied due to its high fucoxanthin content (antioxidant carotenoid). However, pilot and industrial scale experiments to realize continuous and stable production of P. tricornutum and extracted fucoxanthin are limited. For this reason, this research focuses on the study of the fucoxanthin production, going through culture, harvesting, scaling procedure and encapsulation stage. Finally, the optimal culture conditions for a fucoxanthin production of 2.5 mg/day/L were verified. Furthermore, the antioxidant capacity showed a decrease during storage, but still presented a capacity of 18 months, with improved performance when encapsulated with spirulina. The study carried out on encapsulated fucoxanthin-spirulina shows an inhibitory effect on lipogenesis at all concentrations tested in the 3T3-L1 cell line and a lipolytic efficacy at concentrations of 0.2 mg/mL and 0.1 mg/mL in the 3T3-L1 cell line.

An integrated process for enhanced production and purification of fucoxanthin and sulfated polysaccharides in diatom Hyalosynedra toxoneides cultures

BackgroundThis study explores the efficient production and purification of health-promoting compounds, fucoxanthin and sulfated polysaccharides, from the diatom Hyalosynedra toxoneides, contributing to the growing demand for sustainable bioactive compounds. MethodsSemi-continuous cultivation of H. toxoneides (AQ9) in three medium concentrations (2.5f, 5f, 10f) was conducted in a custom-made photobioreactor. Fucoxanthin was extracted using 95 % ethanol, purified through silica gel chromatography, and characterized via high-performance liquid chromatography. Crude polysaccharides were obtained, purified using DEAE-Sephacel resins, and characterized for uronic acid and sulfate content. Significant findingsHigher culture medium concentrations led to increased biomass, fucoxanthin, and polysaccharide yields, providing insights for large-scale cultivation. With a 10f medium in semi-continuous cultures, we achieved the highest yields of approximately 1.18 g/L for cell mass, 4.45 mg/L for fucoxanthin, and 17.20 mg/L for crude polysaccharides, with corresponding productivities of 0.20 g/L/day, 0.74 mg/L/day, and 2.46 mg/L/day. Fucoxanthin was purified from crude pigments with 91 % purity and 70 % recovery. Meanwhile, two uncharacterized sulfated polysaccharides were isolated from crude polysaccharides using anion-exchange chromatography. Notably, the culture media influenced sulfated polysaccharide distribution. This integrated approach contributes to efficient production and purification of bioactive compounds from diatom cultures, with potential applications in diverse industries, including nutraceuticals and cosmetics.

Effects of Temperature, Light and Salt on the Production of Fucoxanthin from Conticribra weissflogii.

Fucoxanthin is a natural active substance derived from diatoms that is beneficial to the growth and immunity of humans and aquatic animals. Temperature, light and salinity are important environmental factors affecting the accumulation of diatom actives; however, their effects on the production of fucoxanthin in C. weissflogii are unclear. In this study, single-factor experiments are designed and followed by an orthogonal experiment to determine the optimal combination of fucoxanthin production conditions in C. weissflogii. The results showed that the optimum conditions for fucoxanthin production were a temperature of 30 °C, a light intensity of 30 umol m-2 s-1 and a salinity of 25. Under these conditions, the cell density, biomass, carotenoid content and fucoxanthin content of C. weissflogii reached 1.97 × 106 cell mL-1, 0.76 g L-1, 2.209 mg L-1 and 1.372 mg g-1, respectively, which were increased to 1.53, 1.71, 2.50 and 1.48 times higher than their initial content. The work sought to give useful information that will lead to an improved understanding of the effective method of cultivation of C. weissflogii for natural fucoxanthin production.

Isolation and cultivation of freshwater diatom <italic>Nitzschia palea</italic> HY1 for increasing biomass and fucoxanthin production

Diatoms, a type of microalgae distributed worldwide, have been identified as potential sources of biomass, lipids, and high-value compounds. While marine diatoms have been extensively studied, the potential of freshwater diatoms still needs to be explored. In this study, a novel strain of freshwater diatom was isolated from the Jungnangcheon stream located in Seoul, Republic of Korea (37°33'08.0" N, 127°02'40.0" E). This newly isolated strain was classified through phylogenetic analysis, and its morphology was investigated using light and electron microscopy; it was named Nitzschia palea HY1. N. palea HY1 grown in freshwater media (FDM) produced higher biomass (0.68 g L<sup>-1</sup>) and fucoxanthin production (9.19 mg L<sup>-1</sup>) than in conventional diatom media. Furthermore, increasing the bicarbonate concentration from 2 to 10 mM enhanced the maximum biomass and fucoxanthin production in FDM by 2.7 fold and 1.5 fold, respectively. Remarkably, the introduction of aeration to the modified FDM (MFDM) led to a substantial increase in the maximum biomass and fucoxanthin production of N. palea HY1, exhibiting 3.8-fold and 4.1-fold enhancement, respectively, compared to FDM alone. These findings suggest that optimizing the cultivation of N. palea HY1 using MFDM could provide an alternative to marine sources for fucoxanthin production.