D-optimal design model and biosynthetic pathway for gentamicin production by Micromonospora purpureochromogenes NRRL B-16094

Abstract Background 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...

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Main Authors: Muath Suliman, Amr S. Bishr, Sally T. K. Tohamy, Mohammad Y. Alshahrani, Khaled M. Aboshanab
Format: Article
Language:English
Published: BMC 2025-05-01
Series:BMC Microbiology
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Online Access:https://doi.org/10.1186/s12866-025-04001-8
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Summary:Abstract Background 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. Methods 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. Results 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. Conclusion 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.
ISSN:1471-2180