Journal of Applied Phycology最新文献

Bisphenol A (BPA) is an emerging organic compound used in the production of epoxy resin, polycarbonate plastics and thermal paper. Following the restrictions on the use of bisphenol A, many substitutes have been produced as its replacement in several consumer products. The main task of this research was to examine the toxic effects of single bisphenol analogues and their mixtures against freshwater microalgae Chlorella vulgaris and Desmodesmus armatus. The findings suggest that bisphenol B, bisphenol C, bisphenol PH (EC₅₀ (14 day): 33.32-43.32 mg L^-1) and bisphenol B, bisphenol C, bisphenol FL, bisphenol PH (EC₅₀ (14 day): 30.49-64.54 mg L^-1) show strong toxic effects towards C. vulgaris and D. armatus, respectively. In turn, the research results indicate that the toxicity of a mixture of examined bisphenol analogs on both species of green algae is much higher (EC₅₀ (14 day): 24.55-32.68 mg L^-1) than the individual toxicity of each component of the mixture. Therefore, it can be concluded that mixtures lead to the occurrence of synergistic effects. The toxicity of the individual bisphenol analogues and their mixture by EC₅₀ (14 day) values in descending order, was as follows: mixture>bisphenol PH> bisphenol B> bisphenol C> bisphenol FL> bisphenol F> bisphenol E for C. vulgaris and bisphenol B> mixture> bisphenol FL> bisphenol C> bisphenol PH> bisphenol E> bisphenol F for D. armatus, respectively. Moreover, the present research expands current knowledge of the ecotoxicological risks of bisphenol analogues to aquatic organisms.

This study assessed the effectiveness of the treatment of tomato seeds with an aqueous extract of the dried biomass of the microalga Anabaena minutissima in protecting the plants from diseases caused by soilborne pathogens like Rhizoctonia solani and Pythium ultimum. The extract, obtained by an autoclave-assisted method at 100 °C, was rich in proteins and carbohydrates (56.6 and 26.9% of total solids). Preliminary tests were performed revealing: i) a moderate direct activity toward pathogen in vitro growth, with ± 9% stimulation/inhibition, depending on the pathogen; ii) a stimulatory/inhibitory activity toward seedling growth, depending on the dose; iii) no effect on the mycelial growth by root exudates of treated plantlets. Then, a greenhouse experiment was set up to test the response of tomato plants in substrates artificially inoculated with the single pathogens, after seed treatment with the extract at different doses (0, 2.5, 5, and 10 mg mL^-1). The treatment generally increased the percentage of standing plants and restored plant development up to the level of healthy controls. Moreover, the disease incidence and severity progressively reduced at increasing doses. Finally, the seed treatment significantly increased some markers of induced systemic resistance like endochitinase and glucanase activity, in hypocotyls of 14-day-old seedlings, compared to non-treated controls. Besides, the treatment increased epicotyls’ carotenoid and chlorophyll a and b content. Overall, these results demonstrate that seed priming with A. minutissima aqueous extract is a promising eco-friendly tool to ameliorate tomato plant responses towards soilborne pathogens, stimulating plant growth and activating induced resistance mechanisms.

Nano-filtered whey permeate (WP), a major by-product of dairy industry, is produced by membrane filtration of whey. The oleaginous microalga Nannochloropsis oceanica was successfully cultivated on WP without salinity and nutrient amendments. Growth, cell characteristics, and fatty acid profile of the cultures were analyzed using microscopy, flow cytometry, and GC analysis. WP was nitrogen limited, comprising primarily protein as a nitrogen source and only small amounts of free inorganic nitrogen (in the form of nitrate). Nannochloropsis oceanica (and associated bacteria) efficiently removed nitrate (100%), protein (87%), and phosphate (74%) from the whey permeate. Microscopic and flow cytometric analysis revealed diverse size distributions in whey permeate cultures, with significant cell aggregation attributed to low-salinity acclimatization and nitrogen limitation. Autofluorescence analysis revealed reduced photosynthetic activity in whey permeate-grown cells, possibly as a consequence of heightened mixotrophic activities on carbon source in the medium. Low nitrogen availability in whey permeate resulted in biomass with a fatty acid profile enriched in saturated fatty acids. Despite this, a considerable level of the omega-3 polyunsaturated fatty acid (in the form of eicosapentanoic acid or EPA) was detected at ca. 16% of total fatty acids. Whey permeate proved beneficial for the growth of N. oceanica and yielded high concentrations of eicosapentaenoic acid in the extracted lipids for potential applications in the feed/food industries.

Edible brown seaweeds of the genus Sargassum have the potential to be utilized as nutrient-rich food components yielding beneficial health effects upon consumption. This study aimed to characterise Sargassum crassifolium for its phytochemical content and antioxidant capacity followed by its utilization as a dry powder in wheat noodles as a flour replacement. Sargassum crassifolium dehydrated powder contained considerable amounts of total phenols (1.13±0.05 mg GAE g^-1 DW), flavonoids (21.07±0.79 mg RE g^-1 DW), fucoidan (2.9±0.48 mg g^-1 DW), fucoxanthin (0.963±0.00 µg g^-1 DW), carotenoids (1.88±0.002 µg g^-1 DW) and tannins (1.88±0.002 mg g^-1 DW), while displaying significant DPPH (2,2-diphenyl-picrylhydrazyl hydrate) radical scavenging activity (23.20±1.73%). The use of 2.5% S. crassifolium as a flour replacement enhanced the sensory properties, nutrient composition and phytochemical content of the noodles. The DPPH radical scavenging activity of 2.5% S. crassifolium noodles (19.88±1.56%) in the cooked form was significantly higher than that of the control noodles containing no seaweed (13.29±2.02%). The results of this study revealed that S. crassifolium can be successfully incorporated in noodles to yield acceptable products that have improved nutrient content and potential functionality.

Microalgae are increasingly recognized as a valuable resource for bolstering sustainability in agriculture. However, current research and patents primarily focus on Chlorella spp., Scenedesmus spp., and Spirulina spp., thus leaving the vast diversity of microalgae relatively unexplored for agricultural applications. Euglena gracilis (Euglenophyta) is a microalga renowned for its resilience to diverse environmental stressors and capability to produce a variety of bioactive metabolites. This study investigated the potential of cultivating E. gracilis in piggery wastewater for nutrient recycling and as a source of beneficial biomolecules, particularly for biostimulant use. Utilizing raw wastewater diluted to 25% (P25) and pre-treated wastewater with photo-Fenton (PF), the research found that E. gracilis exhibited elevated cell density, biomass concentration, and overall cell health in both wastewaters compared to a synthetic medium (BG11-NPK). This was due to its efficient removal of nutrients, especially ammoniacal-nitrogen and phosphate, resulting in a biomass rich in polyunsaturated fatty acids, amino acids, and paramylon content. The whole-cell biomass significantly enhanced the germination index of lettuce and tomato seeds compared to the water control. Additionally, it promoted cell expansion and root formation in cucumber cotyledons, exhibiting similarities to phytohormones such as gibberellin, cytokinin, and auxin. Furthermore, it is suggested that E. gracilis biomass contains molecules related to resistance to environmental stresses, particularly in tomatoes, given the enhancement in the seedling vigor index. E. gracilis exhibited remarkable adaptability to piggery wastewater, recycling nutrients and yielding biomass rich in bioactive molecules with potential as plant biostimulants. These findings significantly contribute to understanding E. gracilis's potential applications in agriculture and developing a circular bioeconomy.