蓝藻是具有不同生物活性的有前景的次级代谢产物的潜在来源，包括抗菌、抗病毒、抗真菌、抗原虫和抗癌活性。为了对抗抗生素耐药性的出现，迫切需要新药，而蓝藻代谢物可以构成替代的新型抗菌药物。其胞外多糖的化学复杂性表明它们有可能成为具有多种生物活性的生物活性分子。本研究旨在从新分离的蓝藻 S. algini MNE ON864447 中生产和优化一种新型藻酸盐聚合物，除了其有前途的抗菌活性之外。我们成功地从尼罗河中分离出了一种新的蓝藻菌株，S. algini MNE ON864447，它产生藻酸盐作为细胞外聚合物。分离的蓝藻藻酸盐通过一系列测试进行鉴定，包括 FTIR、TLC、HPLC、GC-MS 和 1H NMR。 Plackett-Burman 统计设计表明，工作体积 (X1)、培养期 (X2) 和接种量 (X3) 是影响藻酸盐生产的最重要变量。经过 20 天的培养期后，在 400 mL 培养基/L 锥形瓶中使用 4% 接种量时，获得了最高的藻酸盐产量 (3.57 g/L)。提取的海藻酸盐对革兰氏阴性和革兰氏阳性细菌均表现出有效的抗菌活性，链球菌突变体 (NCTC10449) 是对纯化蓝藻藻酸盐最敏感的测试病原体，在 10 mg/mL 纯化藻酸盐下，抑菌圈直径为 34±0.1 mm而霍乱弧菌 (NCTC 8021) 的敏感度最低，在相同的蓝藻藻酸盐浓度下，抑菌圈直径为 22.5±0.05 毫米。这种抗菌活性是抗菌药物开发的关键一步，并对对抗多重耐药细菌提出了新的挑战。© 2023。作者。

Cyanobacteria are a potential source of promising secondary metabolites with different biological activities, including antibacterial, antiviral, antifungal, antiprotozoal, and anticancer activities. To combat the emergence of antibiotic resistance, there is an urgent requirement for new drugs, and cyanobacteria metabolites can constitute alternative new antibacterial medication. The chemical complexity of their exopolysaccharides indicates that they have the potential to be bioactive molecules with many biological activities. The present study aimed to produce and optimise a novel alginate polymer from a newly isolated cyanobacterium, S. algini MNE ON864447, in addition to its promising antibacterial activity. We successfully isolated a new cyanobacterium strain, S. algini MNE ON864447 from the Nile River, which produces alginate as an extracellular polymeric substance. The isolated cyanobacterial alginate was identified using a set of tests, including FTIR, TLC, HPLC, GC-MS, and 1H NMR. Plackett-Burman statistical design showed that working volume (X1), the incubation period (X2), and inoculum size (X3) are the most significant variables affecting the production of alginate. The highest alginate production (3.57 g/L) was obtained using 4% inoculum size in 400 mL medium/L conical flask after 20 days of the incubation period. The extracted alginate showed potent antibacterial activity against both Gram-negative and Gram-positive bacteria and Streptococcus mutants (NCTC10449) are the most sensitive tested pathogen for purified cyanobacterial alginate with inhibition zone diameters of 34 ± 0.1 mm at 10 mg/mL of purified alginate while Vibro cholera (NCTC 8021) the lowest sensitive one and showed inhibition zone diameters of 22.5 ± 0.05 mm at the same cyanobacterial alginate concentration. This antibacterial activity is a critical step in the development of antibacterial drugs and presents a new challenge to fight against multi-resistant bacteria.© 2023. The Author(s).