Department of Marine Biotechnology, University of Science and Technology, Yuseong-gu, Daejeon, Republic of Korea.
J Agric Food Chem. 2013 Apr 10;61(14):3428-34. doi: 10.1021/jf4009229. Epub 2013 Mar 25.
Marine bacteria are a potential source of structurally diversified bioactive secondary metabolites that are not found in terrestrial sources. In our continuous effort to search for new antimicrobial agents from marine-derived bacteria, we isolated bacterial strain 109GGC020 from a marine sediment sample collected from Gageocho, Republic of Korea. The strain was identified as Bacillus subtilis based on a 16s rRNA sequence analysis. After a 7-day fermentation of the B. subtilis strain under optimum growth conditions three new and four known secondary metabolites were discovered using chromatographic procedures, and their biological activities were evaluated against both bacteria and crop-devastating fungi. The discovered metabolites were confirmed by extensive 2D NMR and high-resolution ESI-MS data analyses to have the structures of new macrolactin derivatives gageomacrolactins 1-3 and known macrolactins A (4), B (5), F (6), and W (7). The stereoconfigurations of 1-3 were assigned based on coupling constant values, chemical derivatization studies, and a literature review. The coupling constants were very crucial to determine the relative geometries of olefins in 1-3 because of overlap of the ¹H NMR signals. The NMR data of these compounds were recorded in different solvents to overcome this problem and obtain accurate coupling constant values. The new macrolactin derivatives 1-3 displayed good antibiotic properties against both Gram-positive (S. aureus, B. subtilis, and B. cereus) and Gram-negative (E. coli, S. typhi, and P. aeruginosa) bacteria with minimum inhibitory concentration (MIC) values of 0.02-0.05 μM. Additionally, the antifungal activities of 1-7 were evaluated against pathogenic fungi and found to inhibit mycelial growth of A. niger, B. cinerea, C. acutatum, C. albicans, and R. solani with MIC values of 0.04-0.3 μM, demonstrating that these compounds were good fungicides.
海洋细菌是结构多样化生物活性次生代谢产物的潜在来源，这些产物在陆地来源中不存在。在我们从海洋来源的细菌中不断寻找新的抗菌剂的努力中，我们从韩国伽倻岛的海洋沉积物样本中分离出了细菌菌株 109GGC020。该菌株基于 16s rRNA 序列分析被鉴定为枯草芽孢杆菌。在最佳生长条件下，枯草芽孢杆菌菌株经过 7 天发酵后，使用色谱程序发现了三个新的和四个已知的次生代谢产物，并评估了它们对细菌和作物破坏性真菌的生物活性。通过广泛的 2D NMR 和高分辨率 ESI-MS 数据分析，发现的代谢产物的结构为新的大环内酯衍生物 gageomacrolactins 1-3 和已知的大环内酯 A（4）、B（5）、F（6）和 W（7）。根据偶合常数值、化学衍生化研究和文献综述，确定了 1-3 的立体构型。由于 1-3 中烯烃的 1H NMR 信号重叠，偶合常数非常关键，可用于确定烯烃的相对几何形状。为了解决这个问题并获得准确的偶合常数值，在不同溶剂中记录了这些化合物的 NMR 数据。这些新的大环内酯衍生物 1-3 对革兰氏阳性（金黄色葡萄球菌、枯草芽孢杆菌和蜡状芽孢杆菌）和革兰氏阴性（大肠杆菌、伤寒沙门氏菌和铜绿假单胞菌）细菌均显示出良好的抗生素特性，最小抑菌浓度（MIC）值为 0.02-0.05 μM。此外，还评估了 1-7 对致病真菌的抗真菌活性，发现它们抑制黑曲霉、炭疽菌、交链孢菌、白色念珠菌和茄病镰刀菌的菌丝生长，MIC 值为 0.04-0.3 μM，表明这些化合物是良好的杀菌剂。
