Search Results (5)

This study examines the antioxidant status of four Nostoc and Desmonostoc strains during long-term cultivation in nitrogen-depleted media. Growth rates, retinol and α-tocopherol content, fatty acid composition, and activities of antioxidant enzymes were analysed. The results showed that all tested strains adapted to nitrogen limitation using various cellular mechanisms. Specifically, the strain Nostoc sphaeroides exhibited the highest specific growth rate and elevated glutathione peroxidase activity. The Nostoc commune and Desmonostoc caucasicum strains displayed higher superoxide dismutase activity, suggesting robust antioxidative capabilities. Additionally, Desmonostoc caucasicum exhibited unique adaptive strategies, such as elevated succinate dehydrogenase activity. Generally, fatty acid composition changes showed divergent lipid peroxidation vulnerabilities among the studied strains. Principal component analysis highlighted clear distinctions among the strains in terms of their antioxidant capacities and metabolic adjustments. High retinol content correlated positively with increased catalase activity and fatty acid saturation, whereas α-tocopherol concentration was linked to succinate dehydrogenase activity. The obtained results underscore the robustness of cyanobacterial antioxidant defence systems and highlight their metabolic adaptations under nitrogen deprivation. Understanding these responses offers insight into potential biotechnological applications, such as biofertilizers or therapeutics. Full article

This review examines the history of consumption, life cycle, and culture conditions of seven edible mucilaginous terrestrial cyanobacterial strains—Nostoc flagelliforme, Nostoc commune, Nostoc sphaeroides, Nostoc sphaericum, Nostoc verrucosum, Aphanothece sacrum, and Nostochopsis lobatus—as resilient and sustainable food sources in the face of climate change. Traditionally consumed across various cultures and known for their resilience in extreme environments, these cyanobacteria offer high nutritional value, including proteins, vitamins, and essential fatty acids, making them promising candidates for addressing food security. Their ability to fix nitrogen reduces reliance on synthetic fertilizers, enhancing agricultural applications by improving soil fertility and minimizing dependence on fossil fuel-derived chemicals. Unlike conventional crops, these cyanobacteria require minimal resources and do not compete for arable land, positioning them as ideal candidates for low-impact food production. Despite these advantages, the review highlights the need for scalable and cost-effective cultivation methods to fully realize their potential in supporting a resilient global food supply. Additionally, it underscores the importance of ensuring their safety for consumption, particularly regarding toxin content. Full article

Nostoc sphaeroides is a cyanobacterium known for its valuable health benefits, including antioxidant, anti-inflammatory, and immune-boosting properties, making it a promising addition to functional foods. However, large-scale cultivation has remained necessary due to economic value and decreased yield. This study focused on the effect of varying inoculation densities and seasonal conditions on the growth and quality of N. sphaeroides. The main results were as follows: The highest average fresh weight productivity per unit volume was observed in summer and autumn at an inoculation density of 10 g·L⁻¹, with values of 0.26 g·L⁻¹·d⁻¹ and 0.31 g·L⁻¹·d⁻¹, respectively. In winter and spring, the highest productivity was achieved at an inoculation density of 15 g·L⁻¹, with values of 0.52 g·L⁻¹·d⁻¹ and 1.40 g·L⁻¹·d⁻¹, respectively. Nutritional components varied seasonally, with chlorophyll and carotenoid contents peaking in spring and phycobiliproteins, including phycocyanin, allophycocyanin, and phycoerythrin, reaching their highest levels in summer. The dry weight was greatest in summer, while the total protein content was highest in autumn, with values of 40.87%, 39.66%, and 41.44% for 5 g·L⁻¹, 10 g·L⁻¹, and 15 g·L⁻¹, respectively. In terms of texture, the hardness of N. sphaeroides was highest in autumn at inoculation densities of 5 g·L⁻¹ and 15 g·L⁻¹, with values of 153.96 g and 146.88 g, respectively. At 10 g·L⁻¹, the highest hardness was observed in spring (109.67 g). The elasticity and chewiness of the algae were best in spring across all inoculation densities, with elasticity values of 2.86, 2.54, and 2.07, and chewiness values of 112.37, 120.67, and 75.96 for 5 g·L⁻¹, 10 g·L⁻¹, and 15 g·L⁻¹, respectively. In conclusion, the optimal inoculation density for summer and autumn is 10 g·L⁻¹, while for winter and spring, it is 15 g·L⁻¹. N. sphaeroides exhibits better texture in spring. This study offers valuable information for the large-scale cultivation and functional food applications of N. sphaeroides. Full article

Lipoxygenase (EC1.13.11.12, LOX) has been potentially used in the food industry for food quality improvement. However, the low activity, poor thermal stability, narrow range of pH stability, as well as undesirable isoenzymes and off-flavors, have hampered the application of current commercial LOX. In this study, a putative mini-lipoxygenase gene from cyanobacteria, Nostoc sphaeroides (NsLOX), was cloned and expressed in E. coli BL21. NsLOX displayed only 26.62% structural identity with the reported LOX from Cyanothece sp., indicating it as a novel LOX. The purified NsLOX showed the maximum activity at pH 8.0 and 15 °C, with superior stability at a pH range from 6.0 to 13.0, retaining about 40% activity at 40 °C for 90 min. Notably, NsLOX exhibited the highest specific activity of 78,080 U/mg towards linoleic acid (LA), and the kinetic parameters—K_m, k_cat, and k_cat/K_m—attain values of 19.46 μM, 9199.75 s⁻¹, and 473.85 μM⁻¹ s⁻¹, respectively. Moreover, the activity of NsLOX was obviously activated by Ca²⁺, but it was completely inhibited by Zn²⁺ and Cu²⁺. Finally, NsLOX was supplied in steamed bread and contributed even better improved bread quality than the commercial LOX. These results suggest NsLOX as a promising substitute of current commercial LOX for application in the food industry. Full article

Nostoc colonies have been used as food and medicine for centuries, and their main supporting matrix is polysaccharides, which help Nostoc cells resist various environmental stresses including oxidative stress. Here we isolated a polysaccharide, nostoglycan, from cultured Nostoc sphaeroides colonies and determined its physicochemical properties, which revealed a characteristic infrared absorption spectrum typical of polysaccharides and an amorphous morphology with rough surfaces. We also show that nostoglycan has strong moisture absorption and retention capacities and a high relative viscosity. Using Caenorhabditis elegans models, we then demonstrate that nostoglycan is capable of improving overall survival rate of the animals under increased oxidative stress caused by paraquat. Nostoglycan also reduces reactive oxygen species level, inhibits protein carbonyl formation and lipid peroxidation, and increases activities of superoxide dismutase and catalase in paraquat-exposed nematodes. As oxidative stress may drive tumor progression, we further demonstrate that nostoglycan can suppress the proliferation of several types of tumor cells and induce apoptosis of human lung adenocarcinoma A549 cells via caspase-3 activation. Together, our results yield important information on the physicochemical characteristics and demonstrate the antioxidant and anti-proliferative functions of nostoglycan, and thus provide an insight into its potential in food and health industries. Full article