Journal of Applied Phycology最新文献

Gelidium elegans is a marine red alga widely distributed in the northwestern Pacific Ocean. In Taiwan, wild populations of G. elegans have been gradually declining over the past decade due to global warming and overharvesting. Two types of cultivation experiments with G. elegans were conducted: spore germination experiments under four different temperature conditions and a growth experiment to test the growth condition and longevity of G. elegans in a controlled environment. The sporeling temperatures were set to simulate seawater temperatures between 18 °C and 25 °C, corresponding to seawater temperatures from March to May in Northern Taiwan. This period aligns with the peak growth season for G. elegans. The purpose of this setup was to provide optimal conditions for the germination and growth of seedlings of G. elegans for indoor cultivation. Most of the tetraspores germinated into seedlings under the four temperature conditions (18 °C, 20 °C, 22 °C, 25 °C). However, the seedlings grown between 22 °C and 25 °C stopped growing and turned white after 30–50 days of cultivation. On the other hand, the juveniles cultivated at 18 °C reached adult size (more than 10 cm in length) after more than a year of cultivation in the laboratory. In comparison, the juveniles at 20 °C grew slower than those at 18 °C. In the longevity experiment, the subculture thalli thrived well after three years of cultivation in a controlled environment. Next, outdoor culture experiments will be conducted under natural conditions with different nutrient and irradiance regimes to test the sensitivity of juveniles to water temperature.

Seaweed aquaculture, which takes place mostly in Asia, is a lucrative industry that is valued > US $9 billion. However, technological modifications are needed to ensure economic viability and growth of the seaweed aquaculture industry throughout Europe. While current research is investigating the use of certain mechanised processes in seaweed aquaculture, the impact of pressurised spraying of macroalgal cultures on subsequent growth remains unknown. Here, we aimed to determine the efficacy of a future mechanised seeding procedure by investigating how differing pressure treatments impact upon the growth and percentage cover of zoospores seeded onto twine in the hatchery, using the kelp Saccharina latissima as a model species. Zoospore solutions were subjected to pressures of 1, 2, 3, 4, and 5 bar, before being seeded on hatchery twine and left to grow for 7 weeks. We demonstrate that both percentage cover and sporophyte lengths for S. latissima are significantly reduced by ~ 22% and ~ 61%, respectively, when juvenile zoospores are subjected to increasing pressure from 1 to 5 bar. This indicates that minimal pressure in the use of mechanised hatchery techniques is optimal for growth of seaweed.

The growth of microalgae under different trophic modes is widely considered in the literature. However, the cultivation of some microalgal strains under heterotrophic conditions requires further investigation. Thus, the present study investigated the growth potential of a Brazilian strain of Tetradesmus obliquus (Chlorophyceae, Scenedesmaceae) in terms of heterotrophic metabolism. For this purpose, cultures were generated using different concentrations of glucose (26, 13, and 6.5 g L^–1) and sodium nitrate (0.6 g, 0.3, and 0.15 g L^–1) in culture media. The growth parameters analysed were the maximum biomass achieved and volumetric productivity. The combination of 26 g L^–1 glucose with 0.6 g L^–1 sodium nitrate resulted in the greatest increase in dry weight (9.63 ± 0.15 g L^–1). Then, T. obliquus cultures under heterotrophic conditions were compared with those under photoautotrophic and mixotrophic conditions. The maximum production in heterotrophic cultivation was similar to what had been obtained, while mixotrophic cultivation presented the best result, 14.77 ± 0.06 g L^–1, and photoautotrophic cultivation obtained a maximum biomass of 7.90 ± 0.17 g L^–1. The productivity values achieved were 0.52 ± 0.04 g L^–1 day^–1, 0.98 ± 0.07 g L^–1 day^–1, and 1.24 ± 0.07 g L^–1 day^–1 for photoautotrophic, heterotrophic and mixotrophic cultures, respectively. The results indicated that the Brazilian microalga T. obliquus has the potential to be successfully cultivated heterotrophically.

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Microalgae are gaining considerable attention in the field of cosmeceuticals due to their unique profile. In particular, the diverse range of valuable bioactive compounds isolated from microalgae are known to exhibit multiple properties, including anti-aging, antioxidant, whitening, moisturising, and photoprotection, which have contributed to their distinctive profile. In recent years, there has been an increasing effort around exploration of novel natural biologically active substances from microalgae. This trend is in part driven by the global progression towards a ‘greener’ lifestyle. Since compounds derived from microalgae can offer skin benefits without inducing any adverse effects on human health, they are recognised as promising ingredients for innovative cosmetics and cosmeceutical applications. This review paper provides an overview of the changing balance of reliance on traditional topical agents and the prominent role of microalgae as an alternative source for whitening, photo-protection and anti-aging cosmetic applications.

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Over recent years consumer preference has shifted towards natural-based products, prompting the food, cosmetic, and pharmaceutical industries to explore new natural sources. Algae, particularly seaweeds like Caulerpa racemosa, have emerged as promising candidates due to their nutritional richness and bioactive compounds. This review comprehensively examines the nutritional profile of C. racemosa, covering its carbohydrates, fibers, proteins, amino acids, minerals, lipids, vitamins, and pigments. The alga is rich in bioactive metabolites, including terpenoids, alkaloids, sterols, and other secondary metabolites, which contribute to its health-promoting properties. The potential health benefits of C. racemosa are extensive, including antihypertensive, anti-hyperlipidaemic, antibacterial, antimicrobial, anti-cancer, anti-diabetic, anti-hyperglycaemic, anti-inflammatory, and antioxidant activities. Special emphasis is placed on its antioxidant properties, detailing the total phenol content (TPC), total flavonoid content (TFC), and the overall antioxidant capacity. Additionally, the tyrosinase inhibitory activity of C. racemosa suggests its potential in cosmetic applications. Despite its promising health and industrial uses, the standardization of C. racemosa products remains a challenge due to variability in active compound concentrations. This review underscores the multifaceted benefits of C. racemosa, advocating for its broader utilization in health, nutrition, and cosmetics, highlighting the need for further in-depth studies to fully realize its potential.

The escalating concern over food insecurity, micronutrient deficiencies, and the environmental impacts associated with current dietary practices has intensified research into sustainable, nutrient-dense food alternatives. This study, through a comprehensive scoping review, assessed the potential of macroalgae as a component of sustainable diets, examining their nutritional profile, contaminant levels, and the socio-economic and psychological factors influencing their consumption. Utilizing three major electronic databases—Web of Science, Medline/PubMed, and Scopus—we reviewed original articles in English, Spanish, or Portuguese without time restrictions and supplemented these with grey literature. After thorough screening and exclusion, 32 out of 473 articles were deemed suitable for inclusion. Our findings highlight 39 unique species of edible macroalgae, underscoring their potential to enhance human diets with crucial nutrients such as proteins, vitamin B12, and omega-3 and omega-6 fatty acids. Despite the nutritional promise of macroalgae, concerns regarding the bioavailability of these nutrients and the health risks posed by contaminants such as heavy metals must be addressed. Furthermore, levels of education and food neophobia emerged as significant factors explaining algae consumption and avoidance. The remarkable diversity of edible macroalgae represents a substantial yet underutilized opportunity to promote more sustainable diets. Integration of additional evidence regarding food safety, nutrition, and sociocultural aspects of consumption is needed.

Fertilizer use in agriculture and aquaculture significantly contributes to nitrate-rich effluent discharge into aquatic environments. Porphyra's high surface area/volume enables efficient nutrient assimilation. This study aimed to identify a cost-effective, efficient artificial seawater medium for Porphyra linearis cultivation and determine the optimal nitrate concentration to enhance photosynthetic activity. Porphyra linearis was grown in three different salt media, with photosynthetic and biochemical parameters assessed, showing no differences. The nitrate experiment (7 days) using low-cost salt and varied concentration (0 to 6.5 mM) revealed optimal nitrate uptake at 3 and 5 mM, while 6.5 mM indicated saturation/toxicity. The phycobiliproteins contents did not increase compared to the 0 mM, but exhibited greater functionality, as evidenced by the enhanced photosynthetic parameters. Chlorophyll a peaked in 3 mM, whereas lutein and β-carotene peaked in 0 and 3 mM. The thalli turned greenish and appeared to have degraded branches under 0 mM. Growth rate was the same under all nitrate concentration and higher than under 0 mM. The presence of nitrate increased ETR_{in situ} and ETR_max, whereas the absence decreased the range between optimal irradiance for photoinhibition (Eopt_ETR) and saturated irradiance for photosynthesis (Ek_ETR) and between saturated irradiance for non-photochemical quenching (Ek_NPQ) and Ek_ETR, suggesting that under more nitrate available the algae dissipate less energy. P. linearis showed a wide range of nitrate use without variation in pigment composition in contrast to photosynthetic capacity. The 1.5 and 3 mM in cultivation significantly enhance the photosynthetic response of P. linearis, supporting their potential application in IMTA and bioremediation.

Due to global food demand and need to protect the environment, improving crop productivity while reducing agrochemical use has become crucial. Microalgae offer a potential solution as they exhibit biostimulant and biofertilizer effects, improving both crop and soil quality. This study aimed to assess the impact of suspensions of freeze-dried Chlorella vulgaris (UTEX 265), Scenedesmus obliquus (UTEX 393), and Haematococcus pluvialis (UTEX 2505) biomass in distilled water on lettuce (Lactuca sativa L.) germination and development. Different microalgae treatments, individually and mixtures, were applied. The study evaluated various plant growth parameters and the concentration of nutritional constituents, including reducing sugars, total polyphenols, antioxidant capacity, and chlorophyll a. In the first stage (germination), microalgae treatments (C. vulgaris 2 g (CV2),; C vulgaris 0.66 g, S. obliquus 0.66 g and H. pluvialis 0.7 g (CV0.7:SO0.7:HP0.7) and C. vulgaris 1.5 g and S. obliquus 1.5 g (CV1.5:SO1.5) increased L. sativa seed germination rate and the number of germinated seeds. Significant changes were observed in growth-related variables such as height (CV0.7:SO9.7:HP0.7), stem diameter (C. vulgaris 3 g (CV3)), root length (S. obliquus 3 g (SO3)), and leaf area (CV1.5:SO1.5). In the second stage (plant development), microalgae treatments significantly increased dry weight from 2.71% (CV1.5:SO1.5) to 48.52% (SO3), reduced sugars from 3.20% (CV3) to 59.05% (CV1.5:SO1.5), total polyphenols from 7.99% (CV3) to 40.15% (CV1.5:SO1.5), antioxidant capacity from 0.77% (CV0.7:SO9.7:HP0.7) to 17.40% (CV1:HP1), and chlorophyll a from 23.01% (CV1.5:SO1.5) (p ≤ 0.05). C. vulgaris and S. obliquus in blending were identified as the main microalgae promoting positive effects on L. sativa development. This study confirms that microalgae, particularly C. vulgaris and S. obliquus, can enhance crop quality, specifically in L. sativa . These findings demonstrate the potential of microalgae as biostimulants, supporting their application to improve crop productivity and emphasizing their role in sustainable agriculture.

In many fields of biotechnology, pure microalgae cultures isolated from mixed cultures that exist in nature are needed as raw material sources for the production of high-quality products such as nutraceuticals, cosmetics and biofuels. Regarding the isolation of microalgae, microfluidic systems have gained popularity in recent years due to their low energy and chemical requirements for rapid and effective separation. In this study, optimum flow rates were determined using spiral microfluidics for the separation of microalgae from bacteria, followed by the cultivation of separated microalgae. Then the microalgae obtained in the green phase were subjected to nutrient stress to induce carotenoid production. Carotenoids were extracted after 30-day cultivation, and characterization analyses were performed. Subsequently, the SuperPro Designer® software was used to determine the potential for large-scale carotenoid production from Chlorella minutissima. The experiments showed that the fabricated microfluidic system achieved a separation yield and purity of 84.9% and 93.8%, respectively. Furthermore, a 2.5-fold increase in growth rate and carbohydrate and an approximately 1.3-fold increase in protein, lipid, and pigment contents were observed in the post-chip culture. Additionally, a 170% increase in carotenoids was observed within 20 days after induction with nutrient stress. Also, it was shown that microalgal carotenoids could be produced in large scale from C. minutissima by recultivating post-chip microalgae and subjecting them to nutrient stress. This study considered multiple flow rates in microchannels designed to separate microalgae from bacteria and carotenoid production from sorted microalgae for the first time.

An 8-week feeding trial was conducted to evaluate the impact of dietary Schizochytrium sp. on growth, fatty acid profile, non-specific immunity, and histopathology for Nile tilapia (Oreochromis niloticus) juveniles at initial individual weight of 0.88 ± 0.04 g. A control diet consisting of 40 % protein and 7 % lipid (D0, without Schizochytrium sp. supplementation) was used, along with five Schizochytrium sp. supplemented diets formulated at doses of 5 (D1), 10 (D2), 15 (D3), 20 (D4) and 25 g kg⁻¹ (D5), respectively. Each diet was randomly assigned to three replicate aquaria, each stocked with 50 uniform size and weight fish. At the end of the feeding trial it was found that the inclusion of dietary Schizochytrium sp. significantly enhanced the WGR (weight gain rate) and SGR (specific growth rate) of fish, particularly in the D2 group which exhibited the lowest FCR (feed conversion rate) and highest PER (protein efficiency rate). The whole-body crude lipid content decreased with increasing the levels of dietary Schizochytrium sp., while serum levels of TG (triglycerides) and TC (total cholesterol) also decreased concurrently. The DHA content of fillet was significantly up-regulated with the increase of dietary Schizochytrium sp. (P < 0.05). The activities of ALP (alkaline phosphatase), AST (aspartate transaminase) and ALT (alanine transaminase) in serum were found to be lower in Schizochytrium sp. supplemented treatment compared to the control group, with the lowest value observed in D2 group (P < 0.05). There was a positive correlation between serum lysozyme activity and dietary Schizochytrium sp. levels (P < 0.05). The malonaldehyde content initially declined followed by an increase in response to elevated dietary levels of Schizochytrium sp. with comparatively lower levels observed in the D2 group compared to other experimental groups (P < 0.05). Furthermore, the results of liver and intestinal morphology analysis revealed that 1 g kg^-1 dietary Schizochytrium sp. supplementation could maintain hepatocyte integrity and increase villus height in the intestine. Conversely, excessive intake of Schizochytrium sp. (≥2 g kg^-1) led to nuclear migration and vacuolation in hepatocytes. In conclusion, these findings indicate that dietary Schizochytrium sp. can enhance feed utilization, non-specific immunity, antioxidant capacity, as well as liver and intestinal morphology, ultimately improving the nutritional value of fillets, but excessive supplementation may result in liver tissue lesions.