RESUMEN
During screening for potentially antimicrobial actinobacteria, a highly antagonistic strain, designated WAB9, was isolated from a Saharan soil of Algeria. A polyphasic approach characterized the strain taxonomically as a member of the genus Streptomyces. The strain WAB9 exhibited a broad spectrum of antimicrobial activity toward various multidrug-resistant micro-organisms. A PCR-based assay of genomic potential for producing bioactive metabolites revealed the presence of PKS-II gene. After 6 days of strain fermentation, one bioactive compound was extracted from the remaining aqueous phase and then purified by HPLC. The chemical structure of the compound was determined by spectroscopic (UV-visible, and (1)H and (13)C NMR) and spectrometric analysis. The compound was identified to be 2-amino-N-(2-amino-3-phenylpropanoyl)-N-hydroxy-3-phenylpropanamide, a novel hydroxamic acid-containing molecule. The pure molecule showed appreciable minimum inhibitory concentration values against a selection of drug-resistant bacteria, filamentous fungi and yeasts. Significance and impact of the study: This study presents the isolation of a Streptomyces strain, named WAB9, from a Saharan soil in Algeria. This strain was found to produce a new hydroxamic acid-containing molecule with interesting antimicrobial activities towards various multidrug-resistant micro-organisms. Although hydroxamic acid-containing molecules are known to exhibit low toxicities in general, only real evaluations of the toxicity levels could decide on the applications for which this new molecule is potentially most appropriate. Thus, this article provides a new framework of research.
Asunto(s)
Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Ácidos Hidroxámicos/farmacología , Streptomyces/metabolismo , Levaduras/efectos de los fármacos , Argelia , Antibacterianos/biosíntesis , Antibacterianos/química , Cromatografía Líquida de Alta Presión , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Farmacorresistencia Fúngica Múltiple/efectos de los fármacos , Ácidos Hidroxámicos/química , Ácidos Hidroxámicos/metabolismo , Pruebas de Sensibilidad Microbiana , Suelo , Microbiología del Suelo , Streptomyces/genética , Streptomyces/aislamiento & purificaciónRESUMEN
Two known and two new ortho-phenyl phosphonium-sulfonate compounds have been synthesized and analyzed in solution and in the solid state. When the phosphonium moiety bears alkyl substituents, two rotamers are in equilibrium in solution. These two rotamers have been entirely characterized and are shown to differ by the spatial arrangement of the phosphonium proton relative to the sulfonate moiety. The phosphonium proton chemical shift and the 1JPH coupling constant are characteristic values for each rotamer. The kinetic and thermodynamic constants have been determined by means of NMR and DFT studies.
RESUMEN
An actinobacterial strain, HG29, with potent activity against pathogenic, toxigenic and phytopathogenic fungi was isolated from a Saharan soil sample of Algeria. On the basis of morphological and chemotaxonomic characteristics, the strain was classified in the genus Streptomyces. Analysis of the 16S rRNA gene sequence showed a similarity level of 99.3% with Streptomyces gancidicus NBRC 15412T. The comparison of its cultural and physiological characteristics with this species revealed significant differences. Moreover, the phylogenetic tree showed that strain HG29 forms a distinct phyletic line within the genus Streptomyces. Production of antifungal activity was investigated by following kinetics in shake broth. The highest antifungal activity was obtained after five days of fermentation, and in the dichloromethane extract. Two active compounds, NK1 and NK2, were purified by HPLC using a C18 column. Their chemical structures were identified through nuclear magnetic resonance experiments and mass spectrometry as oligomycins E and A, respectively, which have not been reported to be produced by S. gancidicus. The two bioactive compounds exhibited significant antifungal activity in vitro, showing minimal inhibitory concentrations (MICs) values between 2 and 75µg/mL.
Asunto(s)
Oligomicinas/química , Microbiología del Suelo , Suelo/química , Streptomyces/química , Streptomyces/aislamiento & purificación , África del Norte , Argelia , Antifúngicos/farmacología , Fermentación , Hongos/clasificación , Hongos/efectos de los fármacos , Hongos/aislamiento & purificación , Hongos/patogenicidad , Espectrometría de Masas , Pruebas de Sensibilidad Microbiana , Oligomicinas/aislamiento & purificación , Oligomicinas/farmacología , Filogenia , ARN Ribosómico 16S/genética , Metabolismo Secundario , Análisis de Secuencia de ADN , Streptomyces/clasificación , Streptomyces/genéticaRESUMEN
In a search for new antifungal antibiotics active against Candida albicans and others pathogenic fungi, a strain of actinobacteria, designated G61, was isolated from a Saharan soil and tested for its activity against these microorganisms. The analysis of its 16S rDNA sequence showed a similarity level of 100% with Streptomyces mutabilis NBRC 12800(T). The highest anticandidal activities produced by the strain G61 were obtained on Bennett medium in the fourth day of incubation. The active product, extracted by n-butanol, contained one bioactive spot detected on thin layer chromatography plates. It was purified by HPLC and its chemical structure was determined by spectroscopic analyses as 2,4-Di-tert-butylphenol. The minimum inhibitory concentrations (MIC) of this product against several strains of pathogenic microorganisms are interesting.
Asunto(s)
Antifúngicos , Candida albicans/efectos de los fármacos , Hongos/efectos de los fármacos , Fenoles/metabolismo , Fenoles/farmacología , Streptomyces/metabolismo , África del Norte , Antifúngicos/aislamiento & purificación , Antifúngicos/metabolismo , Antifúngicos/farmacología , Candida albicans/crecimiento & desarrollo , Candida albicans/patogenicidad , Hongos/crecimiento & desarrollo , Hongos/patogenicidad , Pruebas de Sensibilidad Microbiana , Fenoles/aislamiento & purificación , ARN Ribosómico 16S/análisis , Análisis de Secuencia de ADN , Microbiología del Suelo , Streptomyces/clasificación , Streptomyces/genética , Streptomyces/aislamiento & purificaciónRESUMEN
A new strain of actinomycete designated PAL114, producing antimicrobial compounds, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies showed that this strain belonged to the genus Streptomyces. Two bioactive compounds, named P41A and P41B, were extracted by dichloromethane from the cell-free supernatant broth of strain PAL114 and were purified by HPLC. Minimum inhibitory concentrations of the pure antibiotics were determined against yeasts, filamentous fungi and bacteria, most of which are pathogenic or toxigenic for human and multiresistant to antibiotics. The strongest activities were observed against Candida albicans M3 and Bacillus subtilis ATCC 6633. The chemical structures of the compounds were determined by spectroscopic analysis of UV-visible and 1H and 13C NMR spectra and spectrometric analysis of mass spectrum. The compounds P41A and P41B were identified as saquayamycins A and C, respectively. These compounds belong to the aquayamycin-group antibiotics, which are known in the literature for their anticancer and antibacterial activities.
Asunto(s)
Antiinfecciosos/farmacología , Streptomyces/química , África del Norte , Argelia , Antraquinonas/aislamiento & purificación , Antraquinonas/farmacología , Bacillus subtilis/efectos de los fármacos , Bacillus subtilis/crecimiento & desarrollo , Candida albicans/efectos de los fármacos , Candida albicans/crecimiento & desarrollo , Humanos , Pruebas de Sensibilidad Microbiana , Suelo , Microbiología del Suelo , Streptomyces/aislamiento & purificación , Streptomyces/metabolismoRESUMEN
Actinomycete strain SA198, isolated from a Saharan soil sample of Algeria, exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria, and phytopathogenic and toxinogenic fungi. The morphological and chemotaxonomic characteristics of the strain were consistent with those of the genus Saccharothrix. Analysis of the 16S rRNA gene sequence of strain SA198 showed a similarity level ranging between 97.2 and 98.8% within Saccharothrix species, S. australiensis being the most closely related. Two new active products were isolated by reverse HPLC using a C18 column. The ultraviolet-visible (UV-VIS), infrared (IR), mass, and (1)H and (14)C nuclear magnetic resonance (NMR) spectra showed that these products were new bioactive compounds. The minimum inhibitory concentrations of these antibiotics showed a strong activity against fungi and moderate activities against Gram-positive and Gram-negative bacteria.