Suliman Muath, Bishr Amr S, Tohamy Sally T K, Alshahrani Mohammad Y, Aboshanab Khaled M
Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha 9088, P.O. Box 61413, Saudi Arabia.
Department of Microbiology and Immunology, Faculty of Pharmacy , Ain Shams University, Cairo, 11566, Egypt.
BMC Microbiol. 2025 May 20;25(1):309. doi: 10.1186/s12866-025-04001-8.
Micromonospora purpureochromogenes NRRL B-16094, a natural producer of gentamicin (GEN), a 5,6-diglycosylated 2-dexoystreptamine-aminoglycoside antibiotic (2DOS-AGA) broad-spectrum bactericidal activity. In literature, limited studies are concerned with the biosynthetic route and various cultural conditions influencing GEN production.
Therefore, this study aimed to explore the GEN biosynthesis pathway and compare it to that of fortimicin and kanamycin. In addition, four key environmental conditions influencing GEN production were statistically optimized using response surface D-optimal design (DOD). Herein, the biosynthetic pathway of GEN was proposed based on the biochemistry of the identified genes/proteins within the gene cluster. Comparing the GEN-biosynthetic gene cluster to that of kanamycin and fortimicin suggested that gentamicin biosynthesis could have originated from a combination of biosynthetic pathways of both antibiotics.
For the optimization experiments, culture media 4 (CM4) and 6 (CM6) gave the highest specific productivity at 6.36 and 3.80 µg/mg, respectively. A DOD quadratic model was successfully generated to optimize four key environmental factors. Predicted and experimentally confirmed optimized factors were an initial pH of 7, an incubation temperature of 30˚C, and an agitation of 300 rpm for 10 days. This resulted in a 13.5-fold increase (289.5 µg/mL) over that produced by the basic CM1 production medium (21.4 µg/mL) and 2.4 times (over that obtained by CM4 (123.7 µg/mL) as verified by HPLC analysis.
DOD is an efficient tool for optimizing GEN. Accordingly, the optimized conditions are highly advisable during the scaling up of GEN production by M. purpureochromogenes NRRL B-16094.
紫色产色小单孢菌NRRL B - 16094是庆大霉素（GEN）的天然生产者，庆大霉素是一种具有5,6 - 二糖基化的2 - 脱氧链霉胺 - 氨基糖苷抗生素（2DOS - AGA），具有广谱杀菌活性。在文献中，关于庆大霉素生物合成途径以及影响其产生的各种培养条件的研究有限。
因此，本研究旨在探索庆大霉素的生物合成途径，并将其与福提霉素和卡那霉素的生物合成途径进行比较。此外，使用响应面D - 最优设计（DOD）对影响庆大霉素产生的四个关键环境条件进行了统计优化。在此，基于基因簇中已鉴定基因/蛋白质的生物化学提出了庆大霉素的生物合成途径。将庆大霉素生物合成基因簇与卡那霉素和福提霉素的基因簇进行比较表明，庆大霉素的生物合成可能起源于这两种抗生素生物合成途径的组合。
对于优化实验，培养基4（CM4）和6（CM6）的比生产率最高，分别为6.36和3.80μg/mg。成功生成了一个DOD二次模型以优化四个关键环境因素。预测并经实验证实的优化因素为初始pH值7、培养温度30˚C以及搅拌速度300 rpm，培养10天。这导致产量比基本的CM1生产培养基（21.4μg/mL）提高了13.5倍（289.5μg/mL），并且经高效液相色谱分析验证，比CM4（123.7μg/mL）提高了2.4倍。
DOD是优化庆大霉素的有效工具。因此，在紫色产色小单孢菌NRRL B - 16094扩大生产庆大霉素的过程中，高度建议采用优化条件。
