Natural Products and Green Chemistry Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Council of Scientific and Industrial Research (CSIR), Bhavnagar 364002, Gujarat, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Lett Appl Microbiol. 2023 Feb 16;76(2). doi: 10.1093/lambio/ovac026.
The bacterial endophytes isolated from the halophyte Salicornia brachiata were explored for the antimicrobial potential to discover novel microbial inhibitors that combat multidrug resistance. Upon investigation, ethyl acetate extract of the endophyte Bacillus subtilis NPROOT3 displayed significant potency against Mycobacterium smegmatis MTCC6 as well as Mycobacterium tuberculosis H37Rv strain. Further investigation of ethyl acetate crude extract by repeated chromatographic separations followed by characterization using UV, HR-ESI-MS, MALDI-MS, MALDI-MS/MS, CD, and NMR spectroscopy yielded a series of five known siderophores, namely, SVK21 (1), bacillibactin C (2), bacillibactin B (3), tribenglthin A (4), and bacillibactin (5). A total of two out of five compounds, 4 (MIC 38.66 μM) and 5 (MIC 22.15 μM) exhibited significant inhibition against the strain M. smegmatis MTCC6 comparable with positive control rifampicin (MIC 12.15 μM). None of these five bacillibactin molecules are previously reported to exhibit bioactivity against Mycobacterium sp. Herein for the first time, all the compounds were screened for their antibacterial activities against a panel of bacterial pathogens of humans. Furthermore, the probable mechanism of action of bacillibactin compounds for their antimycobacterial activity is also discussed. The findings of this study open up a new chemotype for inhibition of the Mycobacterium sp. and other multidrug-resistant pathogens.
从盐生植物海蓬子中分离得到的内生细菌被探索其具有抗菌潜力，以发现对抗多药耐药性的新型微生物抑制剂。研究发现，内生细菌枯草芽孢杆菌 NPROOT3 的乙酸乙酯提取物对分枝杆菌 MTCC6 和结核分枝杆菌 H37Rv 菌株具有显著的活性。通过重复的色谱分离进一步研究乙酸乙酯粗提取物，并使用 UV、高分辨电喷雾质谱（HR-ESI-MS）、基质辅助激光解吸电离质谱（MALDI-MS）、基质辅助激光解吸电离质谱/质谱（MALDI-MS/MS）、圆二色谱（CD）和核磁共振波谱（NMR）进行表征，得到了一系列五种已知的铁载体，即 SVK21（1）、杆菌素 C（2）、杆菌素 B（3）、三苯并呋喃 A（4）和杆菌素（5）。在总共五种化合物中，有两种化合物 4（MIC 为 38.66 μM）和 5（MIC 为 22.15 μM）对分枝杆菌 MTCC6 表现出与阳性对照利福平（MIC 为 12.15 μM）相当的显著抑制作用。这五种杆菌素分子中没有一种以前被报道对分枝杆菌属具有生物活性。在此首次对所有化合物进行了针对一组人类细菌病原体的抗菌活性筛选。此外，还讨论了杆菌素化合物对抗分枝杆菌活性的可能作用机制。这项研究的结果为抑制分枝杆菌属和其他多药耐药性病原体开辟了一个新的化学型。
