The growing demand for natural products in the pharmaceutical, nutraceutical, cosmetic, food, and feed sectors has stimulated considerable interest in the identification and sustainable production of bioactive compounds from renewable biological resources [...]

Non-alcoholic fatty liver disease (NAFLD), often associated with obesity, has become a serious public health matter. NAFLD is characterized by an excessive lipid accumulation in hepatocytes, mainly stored as triglycerides. The marine microalga Phaeodactylum tricornutum is well known for its richness of bioactive compounds, particularly lipids. Therefore, different natural lipid extracts from P. tricornutum are deciphered to jugulate or prevent obesity leading to NAFLD. In this study, the main focus was on the effects of purified neutral and polar lipid extracts from P. tricornutum in a cellular model of NAFLD. Human HepG2 cells were used and exposed for 24 h to 250 μM palmitate to induce NAFLD with or without microalgal lipid extracts. Data showed that neutral lipid extract presented lower viability and cytotoxic activities on HepG2 at 75 µg/mL. The impact on apoptosis was around 5% and below the threshold. Nevertheless, the use of neutral lipid at 50 µg/mL induced a decrease in the number and size of lipid droplets, and so, preventing NAFLD. On the contrary, the polar lipid extract had no effect on the accumulation of triglycerides in HepG2 cells. To conclude, neutral lipid extract seemed to be a good candidate to prevent NAFLD.

Developing sustainable strategies to enhance microalgal productivity is a major challenge in modern biotechnology. Beyond optimizing light, nutrient supply, and temperature, physical stimulation methods have recently attracted growing interest. Among these, audible sound and ultrasound have emerged as promising tools capable of influencing growth, biomass accumulation, and metabolite production in several microalgal species. Although the available literature is still limited, current evidence suggests that acoustic stimulation can alter cellular physiology through mechanosensitive responses, changes in membrane permeability, and modulation of metabolic activity. This review summarizes current knowledge on the effects of sound waves on microalgae, discusses potential mechanisms involved in acoustic perception, and highlights future research directions.

Chemical fertilizers are widely used to achieve rapid and high-yield crop production. However, their intensive use negatively impacts ecosystems by polluting air and groundwater, accelerating soil acidification and deterioration, and because they rely on energy-intensive production processes and excessive mining. Biofertilizers have emerged as a promising and sustainable solution. Among them, microalgae, particularly species of the genus Chlorella, have attracted significant attention. Chlorella microalgae are an eco-friendly and cost-effective biofertilizer option, with advantages such as ease of cultivation, fast growth and slow release of nutrients when applied to soil. In this context, this review summarizes the potential of Chlorella species as biofertilizers and highlights the important role of its phytohormones in this effect, in addition to its use in wastewater treatment, which results in biomass and water with biofertilizing potential.

Light and salt stress affect the growth of plants and microorganisms, causing photo-oxidative stress. The cyanobacterium Synechocystis is notable for its adaptability to and sustainability in seawater. In this study, the synergistic effects of different light intensities and salt concentrations on the growth and biomass composition of Synechocystis were examined. Cultures were grown in BG11 medium (control) and with 20 and 40 g L−1 marine salts (obtained from a commercial sea water preparation) at 100, 200, and 400 μmoles photons m−2 s−1 (LL, ML, and HL, respectively) to assess the interactive effects of salinity stress and increasing light intensity. The effect of salinity stress was most pronounced under LL and ML, where the highest accumulation of all major carotenoids was observed; under HL, the contents of most carotenoids significantly increased mainly at the highest salt concentration but to a lesser extent). Under LL and ML echinenone reached the highest values (2.71-fold and 3.75-fold higher than in the control, respectively), whereas β-carotene showed the highest increase at LL, reaching concentrations three times those of the control. At HL myxoxanthophyll exhibited the highest increase with marine salt (1.9-fold higher than in the control). The results show that Synechocystis could grow at all light intensities and marine salt concentrations via increased synthesis of carotenoids in response to physiological stress.

Hydrogen (H2) is widely regarded as a critical energy vector for achieving carbon neutrality, owing to its high energy density and CO2-free combustion. Among sustainable production methods, photobiological H2 synthesis using photosynthetic microorganisms has emerged as a promising strategy due to its ability to directly convert light energy into chemical energy. These biological systems use enzymatic pathways such as hydrogenases and nitrogenases to produce H2 from water or organic substrates under moderate conditions. However, practical implementation remains limited by low solar-to-H2 conversion efficiencies, oxygen sensitivity of catalytic enzymes, and technical challenges in photobioreactor systems. This paper reviews the current state of photobiological H2 production, focusing on mechanistic challenges, photobioreactor design, substrate utilisation, and immobilisation techniques. Integrating biological and engineering approaches is expected to play a crucial role in advancing photobiological H2 production towards large-scale implementation.

The cyanobacterium Synechocystis sp. PCC 6803 is a promising candidate for sustainable hydrogen production due to its ability to generate hydrogen under fermentative conditions. This study investigates the impact of marine salt (35 g L−1) supplementation in BG11 medium on the growth, biochemical composition, and hydrogen production of Synechocystis sp. PCC 6803. Cultures were subjected to a three-phase experimental design consisting of growth, nitrogen starvation, and dark fermentation. Marine salt supplementation did not influence growth rate during the initial phase and did not hinder biomass accumulation under nitrogen-deprived conditions. Biochemical analyses revealed that marine salt did not affect carbohydrate accumulation but decreased polyhydroxybutyrate accumulation, while protein content remained comparable between treatments. Notably, cultures grown in marine salt-supplemented media exhibited moderately enhanced hydrogen production, achieving up to 9.14 ± 0.62 mL g-1 dry weight over four days—slightly higher than in control cultures. Our results indicated that carbohydrates accumulated during the nitrogen starvation phase are only partially utilized for hydrogen production during the subsequent phase of dark fermentation, and that more than 90% of the hydrogen produced occurs within the first 3 days. These findings suggest that marine salt not only supports acceptable growth of Synechocystis but also enhances its hydrogen production potential by improving the sustainability of the process.

Microalgae are gaining increasing interest as sustainable feedstocks for producing diverse high-value biomolecules. In this study, a green microalga identified through microscopic and molecular approaches as Tetradesmus sp. LT1 was characterized according to its nutritional requirements, in order to determine stress conditions that maximize carotenoid production. Among the standard culture media, BG-11 supported the highest growth and biomass productivity. Variations in its composition were achieved through nitrogen deprivation and sodium chloride (NaCl) addition. Maximum quantum yield of photosystem II (Fv/Fm), respiration (mu molO2.mL- 1 min- 1), and chlorophyll a were monitored to evaluate the performance of the strain. A threefactor central composite design was further introduced to impose combined nutritional and salinity stress by varying the NaCl, nitrate, and phosphate concentrations. The results indicated that all three factors significantly influenced biomass (optimal value 5.8 g/L) and lipid content (59.1 % under nitrate starvation and phosphate limitation and 47 g/L NaCl). For secondary carotenoids profiled by HPLC-DAD, only NaCl significantly and qualitatively affected their composition, leading to proportional increases in astaxanthin (17 %) and canthaxanthin (20 %). In contrast, violaxanthin increased with decreasing NaCl concentration, reaching 29 %, whereas lutein, the predominant carotenoid under all conditions, remained relatively stable (30-42 %). Overall, these results highlight the potential of Tetradesmus sp. LT1 as a valuable candidate for future biorefinery applications.

In this work, the ability of the photosynthetic purple non-sulfur bacterium Rhodopseudomonas sp. to produce H2 was investigated in two cylindrical photobioreactors (PBRs). The PBRs used in this work had different working volumes: 0.2 L of working volume (named 0.2-PBR) and 4.0 L of working volume (named 4.0-PBR). Two mixing methods were tested in the 4.0-PBR. The first used a rotor with four paddles, and the second a spiral rotor. Additionally, light conversion efficiency (LCE) was assessed for the three conditions tested. The culture in the 0.2-PBR produced 142.15 mL of H2 with an average H2 production rate of 0.74 mL/h, an average productivity of 3.70 mL/L/h and an LCE = 0.59%. The culture in the 4.0-PBR produced a total of 806.05 mL and 1642 mL of H2 with the paddle rotor and the spiral rotor, respectively. The average H2 production rate and LCE of the two rotors were 2.29 mL/h and LCE = 0.58% in the case of the paddle rotor and 2.87 mL/h and LCE = 0.72% in the case of the spiral rotor. The more uniform and thus more efficient mixing of the cells achieved with the spiral rotor played an important role compared to the paddle rotor, resulting in a higher LCE. This study presents a scale-up from 0.2 L to 4.0 L of the photofermentation process using the purple non-sulfur bacterium Rhodopseudomonas sp. S16-VOGS3.

Hydrogen (H2) production by photosynthetic microorganisms is a viable option for renewable energy due to its sustainability and potential for widespread application. Green algae, cyanobacteria, and purple non-sulfur bacteria have shown great promise in bio-H2 production. However, problems such as low H2 production rates and high H2 production costs continue to hinder the commercial scalability of these systems. To overcome these obstacles, genetic engineering selection of robust strains capable of coping with variable environmental conditions, optimization of growth conditions, use of wastewater, and biotechnological approaches such as immobilization are carefully considered. The aim of this review is to provide a thorough overview of the methods and developments that can improve H2 production and to highlight current difficulties and future directions for further studies.

Tanacetum balsamita is a perennial medicinal plant belonging to the Asteraceae family. The species bears a long history as a valuable traditional drug in different cultures, while it is an essential component in the traditional cuisine of several countries. In this context, our literature review aims at providing a comprehensive overview of T. balsamita, covering its traditional uses, phytochemistry, biological activities, and toxicity from 1983 to 2024. Methods: Various databases were used to collect the information, including Scopus, Science Direct, Google Scholar, PubMed, and Web of Science. Results and conclusions: Although many of its traditional uses have gradually faded into obscurity over the centuries, recent decades have rekindled the interest in this species. Recent ethnobotanical surveys have reported the use of this species against various health-related conditions, while current pharmacological studies have corroborated several health benefits of the species, such as antioxidant, antidiabetic, anti-hyperpigmentation, anticancer, and antimicrobial activities. The validated properties are mainly attributed to the presence of multiple phytoconstituents belonging to flavonoids, phenolic acids, terpenes, and fatty acids, which could also indicate potential uses for T. balsamita in the food industry as a natural preservative and flavoring agent of food products.

The production of green hydrogen by microalgae is a promising strategy to convert energy of sun light into a carbon-free fuel. Many problems must be solved before large-scale industrial applications. One solution is to find a microalgal species that is easy to grow, easy to manipulate, and that can produce hydrogen open-air, thus in the presence of oxygen, for periods of time as long as possible. In this work we investigate by means of predictive computational models, the [FeFe] hydrogenase enzyme of Nannochloropsis salina, a promising microcalga already used to produce high-value products in salt water. Catalysis of water reduction to hydrogen by [FeFe] hydrogenase occurs in a peculiar iron-sulfur cluster (H-cluster) contained into a conserved H-domain, well represented by the known structure of the single-domain enzyme in Chlamydomonas reinhardtii (457 residues). By combining advanced deep-learning and molecular simulation methods we propose for N. salina a two-domain enzyme architecture hosting five iron-sulfur clusters. The enzyme organization is allowed by the protein size of 708 residues and by its sequence rich in cysteine and histidine residues mostly binding Fe atoms. The structure of an extended F-domain, containing four auxiliary iron-sulfur clusters and interacting with both the reductant ferredoxin and the H-domain, is thus predicted for the first time for microalgal [FeFe] hydrogenase. The structural study is the first step towards further studies of the microalga as a microorganism producing pure hydrogen gas.

Unicellular algae can produce pure hydrogen gas from water and sun-light. We observed Chlorella vulgaris whole cells when they produce hydrogen using X-band continuous-wave electron spin resonance (ESR). Whole-cell spectroscopy is particularly useful in those cases where purified enzymes are sensitive to oxidant air conditions. By tuning cell preparation, the microwave power, the temperature, the time of air exposure, we could isolate from the background signal candidate markers of hydrogen production. Our observations indicate the presence of a species consistent mainly with an intermediate Fe 3 S 4 + cluster when hydrogen production is high, but not maximal, and when FeS cluster oxidation has just begun. The optimal conditions to detect the above marker by ESR have been identified. Our investigation paves the way to extensive statistical analysis of cellular conditions in future studies using whole-cell ESR.

Microalgae, cyanobacteria, and purple bacteria are photosynthetic microorganisms that are used in many areas, e [...]

The increasing demand for sustainable agricultural practices has led to the exploration of natural biostimulants. This study investigates the effects of tannin extracts obtained via hydrodynamic cavitation and Chlorella vulgaris microalgae on the growth and physiological performance of strawberry (Fragaria x ananassa Duch) plants. A preliminary phytotoxicity test using Lepidium sativum L. confirmed the safety of the tannin water extract. Subsequently, two main experiments were conducted: the first identified the optimal tannin concentration, while the second assessed the individual and combined effects of tannins and C. vulgaris on strawberry plants. The results show that tannin water extract at double concentration of the commercial tannin (54% T.E.) significantly increased leaf dry biomass by 75% and doubled the number of main roots compared to the control. In the second experiment, C. vulgaris at 50% concentration (C1) enhanced fresh leaf biomass by 14% and fresh roots by 20%, while tannin extract (T) showed a declining effect on plant biomass as compared to the control. Positive effects were also observed for root growth in the combined treatment T+C1, with 32% fresh root biomass more than in the control. Regarding fruit, C1 maintained high fruit yield from the beginning of the experiment until September, while T+C1 showed a marked rising trend, reaching a comparable number of fruits to C1, about twofold more than the control. A chemical analysis of the main micro- and macro-elements in roots and leaves resulted in T+C1 having the highest content of Zn and Fe and C1 having the highest content of Fe and K (the latter only in the leaves) as compared to other treatments. In contrast, T+C1 showed about 50% less P and K in the leaves than in C. vulgaris treatments. In addition, in the tannin treatment, microelements such as Fe and Zn accumulated in the roots, evidencing absorption from the soil, but low translocation to the leaves. However, all treatments showed similar photosynthetic performance in terms of leaf gas exchange and chlorophyll fluorescence. These findings suggest that extracts of C. vulgaris and tannins or their blends represent a promising strategy for improving crop productivity and resilience in a sustainable manner.

Photobiological hydrogen production offers a sustainable route to clean energy by harnessing solar energy through photosynthetic microorganisms. The pioneering sulfur-deprivation technique developed by Melis and colleagues in the green alga Chlamydomonas reinhardtii successfully enabled sustained hydrogen production by downregulating photosystem II (PSII) activity to reduce oxygen evolution, creating anaerobic conditions necessary for hydrogenase activity. Inspired by this approach, we present the project of the European consortium PhotoSynH2, which builds on these biological insights and employs synthetic biology to replicate and enhance this strategy in cyanobacteria, specifically, Synechocystis sp. PCC 6803. By genetically engineering precise downregulation of PSII, we aim to reduce oxygen evolution without the unintended effects associated with nutrient deprivation, enabling efficient hydrogen production. Additionally, re-engineering endogenous respiration to continuously replenish glycogen consumed during respiration allows matching oxygen production with consumption, maintaining anaerobic conditions conducive to hydrogen production. This review discusses how focusing on molecular-level processes and leveraging advanced genetic tools can lead to a new methodology that potentially offers improved results over traditional approaches. By redirecting electron flow and optimizing redox pathways, we seek to enhance hydrogen production efficiency in cyanobacteria. Our approach demonstrates how harnessing photosynthesis through synthetic biology can contribute to scalable and sustainable hydrogen production, addressing the growing demand for renewable energy and advancing toward a carbon-neutral future.