Streptomyces sp. AT37 isolated from a Saharan soil produces a furanone derivative active against multidrug-resistant Staphylococcus aureus

Abstract

A novel actinobacterium strain, named AT37, showed a strong activity against some multidrug-resistant Staphylococcus aureus, including methicillin-resistant S. aureus MRSA ATCC 43300, other clinical isolates of MRSA and vancomycin resistant S. aureus VRSA S1. The strain AT37 was isolated from a Saharan soil by a dilution agar plating method using chitin-vitamin agar medium supplemented with rifampicin. The morphological and chemical studies indicated that this strain belonged to the genus Streptomyces. Its 16S rRNA gene sequence was determined and a database search indicated that it was closely associated with the type strain of Streptomyces novaecaesareae NBRC 13368 with 99.6% of similarity. However, the comparison of the morphological and the physiological characteristics of the strain with those of the nearest species showed significant differences. The strain AT37 secreted the antibiotic optimally during mid-stationary phase of growth. One active compound (AT37-1) was extracted from the culture broth with dichloromethane, separated on silica gel plates and purified by HPLC. Based on spectroscopic analysis of UV-Visible, infrared, and H andC NMR spectra and spectrometric analysis, the chemical structure of the compound AT37-1 was identified as 5-[(5E,7E,11E)-2,10-dihydroxy-9,11-dimethyl-5,7,11-tridecatrien-1-yl]-2-hydroxy-2-(1-hydroxyethyl)-4-methyl-3(2H)-furanone. Minimum inhibitory concentrations and minimum biofilm inhibitory concentration (MBIC) of this compound showed significant activity against multidrug-resistant S. aureus with 15-30 and 10-15 μg/mL, respectively.

Actinobacteria from Extreme Niches in Morocco and Their Plant Growth-Promoting Potentials

“…Each soil sample (10 g) was suspended in 90 mL of a sterile saline solution (0.9% (w/v) NaCl in distilled water). The homogenous soil suspension was 10-fold serially diluted with the same sterile saline solution, and 0.1 mL of each dilution was spread onto saline nutrient agar for the marine soil [17] and onto Bennett agar [18] or chitin-vitamin agar [19] for the rest soil samples. The media were supplemented with nalidixic acid (100 µg/mL) and cycloheximide (50 µg/mL) to prevent the growth of Gram-negative bacteria and fungi, respectively.…”

Actinobacteria Derived from Algerian Ecosystems as a Prominent Source of Antimicrobial Molecules

“…AT37 obtained from Adrar Saharan soil (southwest Algeria) the furanone derivative 34 was detected by bioautography of the crude extract, purified by reversed phase HPLC, and identified as the known as antibiotic E-975. The compound exhibited a moderate activity against multidrug-resistant S. aureus and inhibited the biofilm formation, which were reduced by 50% at a concentration of 10-15 µg/mL [100].…”

Streptomyces sp.—A Treasure Trove of Weapons to Combat Methicillin-Resistant Staphylococcus aureus Biofilm Associated with Biomedical Devices

“…In recent years, there have been various bioactive compounds with anti-staphylococcal and anti-MRSA biofilms activity in a wide variety of chemotypes, reported from drug discovery studies investigating the biosynthetic potentials of Streptomyces bacteria. Several bioactive compounds, isolated from Streptomyces sp., were shown to exhibit promising antibiofilm activities that prevent biofilm formation and disrupt the preformed biofilms of S. aureus and MRSA at the micromolar range, including alnumycin D (1), granaticin B (2), kalafungin (3), medermycin (4) [63], AT37-1 (5) [64], collismycin C (6), napyradiomycin SF2415B3 ( 7) [65], hygrocin C ( 8) [66], 8-O-metyltetrangomycin (10) [67], antibiotic 5812-A/C [68], panglimycin D (11) [69] and streptorubin B ( 14) [70] (Table 1). The chemical structures of these compounds are illustrated in Figure 1.…”

“…derived from Saharan soil sample in Adrar. The study indicated that this compound belongs to the group of furanone and the heterocycles family, achieving 50% biofilm inhibitory activity against methicillin-susceptible S. aureus (MSSA) and MRSA, at concentrations between 5 to 10 µg/mL [64].…”