Screening and Characterization of Streptomyces spp. Isolated from Three Moroccan Ecosystems Producing a Potential Inhibitor of the Drug Efflux Pump AcrAB-TolC

Abstract

Traditional antimicrobial antibiotics are increasingly suffering from the emergence of multidrug resistance among pathogenic microorganisms. The antibiotic era is threatened by the ruthless rise of resistance in bacterial infections. A significant role in these resistance profiles is attributed to multidrug efflux pumps. Hence, much effort is being directed towards developing new compounds to overcome this problem. During our screening program of efflux pumps inhibitors (EPI) produced by bioactive Moroccan Actinobacteria, 210 isolates were screened for their antibacterial activities against Escherichia coli strains containing a system of efflux pump AcrAB-TolC, fully functional, and its mutant, inactivated due to the insertion of transposon Tn903 in AcrAB operon, using the method of agar disc diffusion. The results showed that 14 isolates were able to produce EPI as they were active against the wild type strain but not against the mutant in comparison with the synthetic inhibitor L-Phe-L-Arg-β-naphthylamide (PaβN). We focused on the highest EPI activity produced by four strains (Z332, Z35/G, Z385/b and 136). Taxonomic studies and the 16S rDNA sequence indicated that these strains belonged to the Streptomyces species. This work could contribute to the discovery of a new class of antibacterial agents that could expand the therapeutic arsenal.

Synergy between Genome Mining, Metabolomics, and Bioinformatics Uncovers Antibacterial Chlorinated Carbazole Alkaloids and Their Biosynthetic Gene Cluster fromStreptomyces tubbatahanensissp. nov., a Novel Actinomycete Isolated from Sulu Sea, Philippines

“…Tolerance to NaCl was carried out by growing S. tubbatahanensis DSD3025 T in MM1 agar with different NaCl concentrations (0, 2.6, 3, 5, 7, 10, 12, 15% [wt/vol]). Enzymatic and biochemical characteristics of S. tubbatahanensis DSD3025 T were analyzed using a commercially available API ZYM kit (bioMérieux, Marcy-l’Étoile, France) ( 89 – 91 ). The API strips were inoculated according to the manufacturer’s instructions.…”

Revealing Genome-Based Biosynthetic Potential of Streptomyces sp. BR123 Isolated from Sunflower Rhizosphere with Broad Spectrum Antimicrobial Activity

“…The isolate BR123 was checked for antimicrobial potential through the agar-well diffusion method [ 21 ] against 2 gram-positive bacteria ( Staphylococcus aureus and Bacillus subitilis ), 4 gram-negative bacteria ( Salmonella typhi , Xanthomonas oryzae , Escherichia coli and Pseudomonas aeruginosa ), and 4 fungi ( Aspergillus flavus , Aspergillus niger , Fusarium solani and Fusarium oxysporum ) by using 7 different media ( Supplementary Table S1 ). Plates were overlaid with the test culture and wells were filled with the supernatant of BR123.…”