Zhang Qingyun, Lv Daotong, Gong Huiyu, Ren Jiayi, Lyu Yunbin, Wang Shaochen, Feng Zhiyang
College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.
Braz J Microbiol. 2025 Jul 11. doi: 10.1007/s42770-025-01735-5.
A novel actinomycete strain, Streptomyces sp. NRRL S-1813 was employed to study its secondary metabolites under different mediums to activate its cryptic gene clusters and produce antimicrobial secondary metabolites. During fermentation optimization, and purification, oxazolomycin A and oxazolomycin A2 were isolated from one strain simultaneously. Their structure was elucidated using a series of characterization techniques, including full wavelength scanning, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. Oxazolomycin A2 was found not to be a typical enzymatic product of fermentation process. Instead, a spontaneous, non-enzymatic ring cleavage reaction was identified as mechanism for conversion of oxazolomycin A to oxazolomycin A2. Basing on these results, if the target product is oxazolomycin A2, the best fermentation condition of Streptomyces sp. NRRL S-1813 should be the Medium B under the alkalescence condition. For the biosynthesis of oxazolomycin A, the medium pH and reaction time were both important. A slightly acidic environment suppresses the side reactions such as hydrolysis of product, while reasonable reaction time minimizes accumulation of byproducts.
一种新型放线菌菌株，链霉菌属NRRL S - 1813，被用于研究其在不同培养基下的次级代谢产物，以激活其隐秘基因簇并产生抗菌次级代谢产物。在发酵优化和纯化过程中，同时从一个菌株中分离出了恶唑霉素A和恶唑霉素A2。使用一系列表征技术，包括全波长扫描、质谱（MS）和核磁共振（NMR）光谱对它们的结构进行了阐明。发现恶唑霉素A2不是发酵过程的典型酶促产物。相反，一种自发的、非酶促的环裂解反应被确定为恶唑霉素A转化为恶唑霉素A2的机制。基于这些结果，如果目标产物是恶唑霉素A2，链霉菌属NRRL S - 1813的最佳发酵条件应该是碱性条件下的培养基B。对于恶唑霉素A的生物合成，培养基pH和反应时间都很重要。略酸性环境可抑制产物水解等副反应，而合理的反应时间可使副产物积累最小化。
