Department of Pharmacy, University of Rajshahi, Rajshahi, Bangladesh.
Department of Pharmacy, Pabna University of Science and Technology, Pabna, Bangladesh.
BMC Microbiol. 2021 Apr 17;21(1):116. doi: 10.1186/s12866-021-02175-5.
To tackle the problem of antibiotic resistance, an extensive search for novel antibiotics is one of the top research priorities. Around 60% of the antibiotics used today were obtained from the genus Streptomyces. The river sediments of Bangladesh are still an unexplored source for antibiotic-producing bacteria (APB). This study aimed to isolate novel APB from Padma and Kapotakkho river sediments having the potential to produce antibacterial compounds with known scaffolds by manipulating their self-protection mechanisms.
The antibiotic supplemented starch-casein-nitrate agar (SCNA) media were used to isolate antibiotic-resistant APB from the river sediments. The colonies having Streptomyces-like morphology were selectively purified and their antagonistic activity was screened against a range of test bacteria using the cross-streaking method. A notable decrease of the colony-forming units (CFUs) in the antibiotic supplemented SCNA plates compared to control plates (where added antibiotics were absent) was observed. A total of three azithromycin resistant (AZR) and nine meropenem resistant (MPR) isolates were purified and their antagonistic activity was investigated against a series of test bacteria including Shigella brodie, Escherichia coli, Pseudomonas sp., Proteus sp., Staphylococcus aureus, and Bacillus cereus. All the AZR isolates and all but two MPR isolates exhibited moderate to high broad-spectrum activity. Among the isolates, 16S rDNA sequencing of NAr5 and NAr6 were performed to identify them up to species level. The analyses of the sequences revealed that both belong to the genus Streptomyces.
The results from these studies suggest that manipulation of the self-resistance property of APB is an easy and quick method to search for novel APB having the potential to produce potentially novel antibacterial compounds with known scaffolds.
为了解决抗生素耐药性问题，广泛寻找新型抗生素是首要研究重点之一。目前使用的抗生素约有 60%来自链霉菌属。孟加拉国的河流沉积物仍然是产生抗生素的细菌（APB）的未开发来源。本研究旨在从帕德玛河和卡波塔科霍河的沉积物中分离具有产生具有已知支架的抗菌化合物潜力的新型 APB，通过操纵其自我保护机制。
使用添加抗生素的淀粉-酪蛋白-硝酸盐琼脂（SCNA）培养基从河沉积物中分离抗生素抗性 APB。选择性纯化具有链霉菌样形态的菌落，并使用交叉划线法筛选其对一系列测试细菌的拮抗活性。与对照平板（未添加添加抗生素）相比，添加抗生素的 SCNA 平板上的菌落形成单位（CFU）明显减少。共分离出 3 株阿齐霉素耐药（AZR）和 9 株美罗培南耐药（MPR）分离株，并对一系列测试细菌（包括痢疾志贺氏菌、大肠杆菌、假单胞菌、变形杆菌、金黄色葡萄球菌和蜡样芽孢杆菌）进行了拮抗活性研究。所有 AZR 分离株和除两个 MPR 分离株之外的所有分离株均表现出中等到高广谱活性。对 NAr5 和 NAr6 进行 16S rDNA 测序以鉴定其种水平。序列分析表明，两者均属于链霉菌属。
这些研究结果表明，操纵 APB 的自我抗性特性是一种简单快捷的方法，可以搜索具有产生具有已知支架的潜在新型抗菌化合物潜力的新型 APB。
