Journal of Applied Phycology最新文献

Although it is unanimous among scientists and researchers that the food production chain is a substantial contributor to environmental challenges, so far, no food ingredient has been evaluated for its environmental performance relative to planetary boundaries. Given this, this study conducts an analysis oriented to food key ingredients considered essential in human nutrition, namely: proteins, β-carotene as a precursor of vitamin A, and polyunsaturated fatty acids (docosahexaenoic and eicosapentaenoic acids), using life cycle assessment (LCA) linked to the planetary boundary structure, under nine indices: climate change, biosphere integrity, global biogeochemical fluxes, stratospheric ozone depletion, ocean acidification, global freshwater use, land use change, chemical pollution, and atmospheric aerosol loading. Protein sources from animals such as beef, pork, and poultry, β-carotene from palm oil and synthetic routes, and fatty acids from fish oil were also compared to alternative sources from microalgae-based ingredients. The results show that protein ingredients of animal origin and alternatives have largely contributed to the disruption of planetary boundaries. However, the worst environmental performance for protein ingredients studied was attributed to bovine protein, matching three risk indices (climate change, ecotoxicity, and photochemical ozone formation) out of the nine evaluated. On the other hand, among fine chemical food ingredients, only vitamin A from palm oil, which is mostly found in a risk and uncertainty zone, when compared to conventional synthetic processes and microalgae-based; these, in turn, operate fully within safe limits. In contrast, only one planetary index is assigned to the uncertainty zone for polyunsaturated fatty acids from fish oil, the others operate in safe zones equally for microalgae-based processes. Therefore, the conclusions highlight major challenges the food production chain faces to achieve safe and sustainable food. These results guide critical food groups and environmental indicators to prioritize in future efforts to reduce environmental impact.

As global demand for seafood increases, recirculating aquaculture systems (RAS) have gained prominence for sustainable fish rearing. The sustainability of RAS still requires improvement, particularly managing the fish waste. Here we investigated the growth and nutrient removal capabilities of three microalgal species (Isocrysis galbana, Phaeodactylum tricornutum and Skeletonema marinoi) in aquaculture wastewater (AWW) mixed at different concentrations with cultivation medium. All three microalgae showed growth in different concentrations of the AWW obtained from an Atlantic salmon RAS facility in Agder, Norway. The average growth rates for I. galbana, S. marinoi and P. tricornutum at 75% AWW concentration were 0.31± 0.00 day^-1, 0.34 ± 0.00 day^-1, 0.25 ± 0.02 day^-1, respectively. All three species effectively contributed to nitrate, ammonium and phosphate removal. When cultivated in 75% AWW, the microalgae achieved nearly complete removal of nitrite, nitrate, and phosphate, while approximately 90% of ammonium was also removed. Our results confirm the viability of AWW for microalgal cultivation on a laboratory scale suggesting this presents a sustainable route to further develop a circular bioeconomy in aquaculture.

Kappaphycus alvarezii is the fifth most cultivated macroalga in the world, with many industrial applications. Understanding the advances in research on K. alvarezii is essential to further biotechnological applications. Using PRISMA criteria a study was carried out on the CAPES Journals Portal database, between 2017-2023, with “Kappaphycus alvarezii” as single descriptor. Results (n = 559) were obtained and after defining the criteria, 152 manuscripts were subdivided into the following areas: cosmetics (n = 5), animal nutrition (n = 12), human food (n = 20), health/medicine (n = 33), agriculture (n = 34), and general industry (n = 48). From the results, the use of K. alvarezii biomass in the formulation of cosmetics for skin treatment and as a curative can be highlighted. Broad benefits were reported to humans and animals in food and feed supplementation. Moreover, in view of its bioactivities, certain metabolites have the potential to be used for developing new drugs due to their antitumor, antidiabetic, anti-inflammatory and neuroprotective activities. In agriculture, using various processes to make an extract, increases of plant yield and quality have been observed, reducing biotic and abiotic stresses and as a resistance elicitor. Kappaphycus alvarezii biomass has been used for producing biofuel and nanomaterials developments, and for the production of biofilms, especially for the food packaging industry. Thus, K. alvarezii presents wide industrial applications, not only due to the use of carrageenan. Therefore, it deserves further innovations, as it represents a matrix rich in bioactive compounds and is environmentally friendly, possibly replacing harmful ingredients currently used by industry.

Microalgae are photosynthetic microorganisms that have the capacity to synthesize a diverse range of biomolecules depending on their phylogenetic classification. Microalgae hold promise as sustainable and renewable energy resources; however, their full potential remains untapped due to the costliness and time-intensive nature of downstream processing. The objective of this study is to overcome these challenges by utilizing a single processing unit for the extraction of three major biomolecule classes namely, lipids, proteins, and carbohydrates. These biomolecules of marine Chlorella sp. NITT 02 were recovered in a single extraction process using the triphasic system. The parameters defining the triphasic system were optimized for the maximum recovery of biomolecules using Response Surface Methodology (RSM) coupled Genetic Algorithm (GA) optimization. The simultaneous complete recovery of lipids with 86.46 % of total fatty acids, 97 % protein recovery and 97.1 % carbohydrate recovery were obtained with i) 2.5:1 of t-butanol:culture volume, ii) 70 % t-butanol, iii) 32.9 % ammonium sulfate, and iv) 55 min sonication time. All three extracted biomolecule classes were characterized using FTIR, GC-MS, UV-Visible spectrophotometry, and XRD. From the current investigation, the recovery efficiency of the triphasic system is higher than the conventional sequential extraction of biomolecules and the time taken for extraction is 1.25 h with energy consumption of 0.7833 kWh. Hence, the adoption of this biorefinery approach is suitable for making microalgae commercially viable for producing valuable products from the biomolecules.

Microalgae are unicellular photosynthetic microorganisms typically found in aquatic environments and they play a vital role in the global carbon and energy cycles. Discrimination of dead and live cells is an important factor in microalgae research and environmental monitoring. Numerous research on the effects of various microalgae has been conducted concerning cell viability. Recently, dyes such as Trypan Blue (TB), Evans Blue (EB), and Neutral Red (NR) have been employed to assess the viability of microalgae. Existing approaches for identifying dead and living microalgal cells all have flaws, such as the requirement for staining and pre-treatment. A machine learning method was created to distinguish the living and dead microalgal cells by using of a digital holography microscopy, and the accuracy of this technique was greater. The machine learning method offers a new way of studying both freshwater and marine microalgal cell cultures. This review focuses on the existing methods and emerging technology for determining dead and living microalgae cells. This review work will enlighten the new research for the detection of live or dead microalgae.

The present study investigated the impact of seasonal variation on biomass availability, proximate composition, fatty acid profile, minerals content, pigments, moisture content, and elemental composition of an edible green alga Gayralia brasiliensis collected from Shirgaon estuary Maharashtra, west coast of India. Additionally, the physico-chemical parameters of the Shirgaon estuary were analyzed and correlated with biomass abundance and biochemical composition of G. brasiliensis. The findings of the present study demonstrated a significant variation in the physico-chemical parameters of seawater throughout the seasons. During the summer season, the biomass abundance (258.23 ± 23.06 g m^-2 FW), and the total protein content (11.12 ±1.37 % DW) were found highest while the total lipid content declined considerably. Nonetheless, the contents n-6 and n-3 PUFA increased significantly over the winter season. The concentration of micro-elements was highest during the winter season while the macro-elements found plenty during the monsoon season. The correlogram analysis revealed that biomass, total protein, total carbohydrate, chlorophyll pigments, and tissue C, H, N, and S were positively correlated with each other throughout all three seasons. Based on Pearson corelation analysis it is confirmed that among the environmental parameters, irradiance and temperature were found the most limiting factors for the growth of G. brasiliensis. Further, dissolved inorganic nitrate significantly influence the growth of G. brasiliensis negatively. Overall, the results of this study imply that G. brasiliensis should be harvested for desired metabolites during the respective seasons. The findings of the present study are expected to be extremely valuable for future cultivation strategies and edible applications of G. brasiliensis in India.

This study aimed to develop anode with improved performance for potential use in energy applications, particularly in bio-photovoltaic applications. The study comprises the chemical synthesis of a conducting nanocomposite based on reduced graphene oxide and polypyrrole (rGO/PPy) by incorporating PPy into the rGO sheets along with the addition of an aerogel synthesis phase to improve the composite's overall characteristics. A comparative electrochemical analysis was conducted on cyanobacteria (Nostoc sp.) immobilised ITO-PET and modified rGO/PPy/ITO-PET anodes to investigate the photocurrent output of both. The rGO/PPy nanocomposite was further used to develop a cyanobacteria immobilised biofuel cell anode, and the electrochemical characterization of the fabricated bio-anode (rGO/PPy/ITO-PET) was carried out in a lab-made rudimentary electrochemical cell for the bio-electrocatalytic photolysis of water (light) and oxidation of stored organic matter (night). The results show that the modified bio-anode, for the bio-electrocatalytic reaction in the photo-bio-electrochemical cell configuration, attained a maximum current density of 0.132 mA cm^-2 in light, and 0.069 mA cm^-2 in dark at 0.0 V, and 0.375 mA cm^-2 in light, and 0.207 mA cm^-2 in dark at an applied voltage of 1.45 V. Therefore, the electrocatalytic photolysis and oxidation of organic materials were accomplished by the proposed bio-anode via the direct electron transfer mechanism. The amperometric photocurrent response of the developed bio-electrode remained relatively stable for approximately 10 days in the rudimentary designed bio-electrochemical cell. The study demonstrates the potential of rGO/PPy/ITO-PET based bio-electrode for possible application in developing the bio-photovoltaic cells for energy generation.

Sea lettuce (Ulva) is a genus of green macroalgae present along all the coasts of the world's oceans. It represents about 100 species with diverse habitats. Inter- and intra-species natural variation is very large, both in terms of growth characteristics and biomass biochemical composition. As a result, Ulva biomass has a wide range of applications and strain selection can achieve significant increases in yield(s). Establishing solid, long term and cost-effective methodologies for the conservation of Ulva genetic diversity is then required to safeguard and reuse selected strains. Here, we report a cryopreservation-based protocol for the long-term preservation of foliose Ulva strains. Strains from seven different Ulva species were cryopreserved for 15 and/or 120 days in liquid nitrogen, and of the 3 replicates cryopreserved, at least one survived, allowing us to successfully recover all strains. On average, among all specimen cryo-preserved, 82% of them survived and grew post cryo-preservation.