Background: The rise of antibiotic-resistant bacteria necessitates the discovery of new, safe, and bioactive antimicrobial compounds. The antibacterial and antibiofilm activity of microalgae makes them a potential candidate for developing natural antibiotics to limit microbial infection in various fields. Objective: This study aimed to analyze the antibacterial effect of the methanolic extract of Schizochytrium sp. S31 microalgae by broth microdilution and spot plate assays. Methods: The antibacterial effects of Schizochytrium sp. S31 extract was studied on gramnegative pathogens, Pseudomonas aeruginosa, Escherichia coli 35218, Klebsiella pneumonia, which cause many different human infections, and the gram-positive pathogen Streptococcus mutans. At the same time, the antibiofilm activity of the Schizochytrium sp. S31 extract on Pseudomonas aeruginosa and Escherichia coli 35218 bacteria were investigated by crystal violet staining method. Results: Schizochytrium sp. S31 extract at a 60% concentration for 8 hours displayed the highest antibacterial activity against P. aeruginosa, E. coli 35218, and K. pneumonia, with a decrease of 87%, 92%, and 98% in cell viability, respectively. The experiment with Streptococcus mutans revealed a remarkable antibacterial effect at a 60% extract concentration for 24 hours, leading to a notable 93% reduction in cell viability. Furthermore, the extract exhibited a dose-dependent inhibition of biofilm formation in P. aeruginosa and E. coli 35218. The concentration of 60% extract was identified as the most effective dosage in terms of inhibition. Conclusion: This research emphasizes the potential of Schizochytrium sp. S31 as a natural antibacterial and antibiofilm agent with promising applications in the pharmaceutical sectors. This is the first study to examine the antibacterial activity of Schizochytrium sp. S31 microalgae using broth microdilution, spot plate assays, and the antibiofilm activity by a crystal staining method. The findings of this study show that Schizochytrium sp. S31 has antibacterial and antibiofilm activities against critical bacterial pathogens.

中文翻译：

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海洋微藻裂殖壶菌属 sp. S31：新型抗菌剂和抗生物膜剂的潜在来源

背景：抗生素耐药性细菌的兴起需要发现新的、安全的、具有生物活性的抗菌化合物。微藻的抗菌和抗生物膜活性使它们成为开发天然抗生素以限制各个领域微生物感染的潜在候选者。 【摘要】：目的:分析裂殖壶菌甲醇提取物的抗菌作用。 S31 微藻通过肉汤微量稀释和点板测定。方法：裂殖壶菌的抗菌作用。 S31 提取物针对引起多种不同人类感染的革兰氏阴性病原体、铜绿假单胞菌、大肠杆菌 35218、肺炎克雷伯菌以及革兰氏阳性病原体变形链球菌进行了研究。同时，裂殖壶菌的抗生物膜活性。采用结晶紫染色法研究了S31提取物对铜绿假单胞菌和大肠杆菌35218细菌的作用。结果：裂殖壶菌属。 60%浓度的S31提取物8小时对铜绿假单胞菌、大肠杆菌35218和肺炎克雷伯菌表现出最高的抗菌活性，细胞活力分别下降87%、92%和98%。变形链球菌实验显示，60% 提取物浓度持续 24 小时具有显着的抗菌效果，导致细胞活力显着降低 93%。此外，提取物对铜绿假单胞菌和大肠杆菌 35218 中的生物膜形成表现出剂量依赖性抑制作用。就抑制而言，60% 提取物的浓度被确定为最有效的剂量。结论：这项研究强调了裂殖壶菌的潜力。 S31作为一种天然抗菌剂和抗生物膜剂，在制药领域具有广阔的应用前景。这是第一项检查裂殖壶菌属 sp. 抗菌活性的研究。使用肉汤微量稀释、点板测定和晶体染色方法测定 S31 微藻的抗生物膜活性。这项研究的结果表明，Schizochytrium sp。 S31 对关键细菌病原体具有抗菌和抗生物膜活性。