Production of Ramoplanin and Ramoplanin Analogs by Actinomycetes.
Ramoplanin is a glycolipodepsipeptide antibiotic obtained from fermentation ofActinoplanessp. ATCC 33076 that exhibits activity against clinically important multi-drug-resistant, Gram-positive pathogens including vancomycin-resistantEnterococcus(VRE), methicillin-resistantStaphylococcus aureus(MRSA), and vancomycin-intermediate resistantClostridium difficile. It disrupts bacterial cell wall through a unique mechanism of action by sequestering the peptidoglycan intermediate Lipid II and therefore does not show cross-resistance with other antibiotics. However, while demonstrating excellent antimicrobial activity in systemic use in animal models of infection, ramoplanin presents low local tolerability when injected intravenously. As a consequence of this limitation, new derivatives are desirable to overcome this issue. During a natural product screening program developed to discover compounds that disrupt bacterial cell wall synthesis by inhibiting peptidoglycan transglycosylation through binding to the intermediate Lipid II, 49 actinomycete strains were identified by HR-LCMS as producers of ramoplanin-related compounds. The producing strains were isolated from environmental samples collected worldwide comprising both tropical and temperate areas. To assess the diversity of this microbial population, the 49 isolates were initially identified to the genus level on the basis of their micromorphology, and 16S sequencing confirmed the initial identification of the strains. These analyses resulted in the identification of members of genusStreptomyces, as well as representatives of the familiesMicromonosporaceae, Nocardiaceae, Thermomonosporaceae, andPseudonocardiaceae, suggesting that the production of ramoplanins is relatively widespread among Actinomycetes. In addition, all of these isolates were tested against a panel of Gram-positive and Gram-negative bacteria, filamentous fungi, and yeast in order to further characterize their antimicrobial properties. This work describes the diversity of actinomycete strains that produced ramoplanin-related compounds, and the analysis of the antimicrobial activity exhibited by these isolates. Our results strongly suggest the presence of new ramoplanin-analogs among these actinomycete producers.
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Mercedes
M
de la Cruz
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Ignacio
I
González
Merck Research Laboratories, Merck Kenilworth, NJ, USA.
Craig A
CA
Parish
Merck Research Laboratories, Merck Kenilworth, NJ, USA.
Russell
R
Onishi
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
José R
JR
Tormo
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Jesús
J
Martín
Biotechnology Programme, Spanish National Cancer Research Centre Madrid, Spain.
Fernando
F
Peláez
Merck Research Laboratories, Merck Kenilworth, NJ, USA.
Debbie
D
Zink
Centre des Sciences et Techniques, Université Ibn Zohr Agadir, Morocco.
Noureddine
N
El Aouad
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Fernando
F
Reyes
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Olga
O
Genilloud
Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía Granada, Spain.
Francisca
F
Vicente
actinomycetes; antibacterial activity; high-throughput screening; microbial natural products; peptidoglycan intermediate Lipid II; ramoplanin