A Novel Hydroxamic Acid-Containing Antibiotic Produced by a Saharan Soil-Living Streptomyces Strain A
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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Open Archive Toulouse Archive Ouverte . . . . A novel hydroxamic acid-containing antibiotic produced by Streptomyces a Saharan soil-living strain 1,2 1 3 1 4 4 5 1 A. Yekkour , A. Meklat , C. Bijani , O. Toumatia , R. Errakhi , A. Lebrihi , F. Mathieu , A. Zitouni 1 and N. Sabaou 1 Laboratoire de Biologie des Systemes Microbiens (LBSM), Ecole Normale Superieure de Kouba, Alger, Algeria 2 Centre de Recherche Polyvalent, Institut National de la Recherche Agronomique d’Algerie, Alger, Algeria 3 Laboratoire de Chimie de Coordination (LCC), CNRS, Universite de Toulouse, UPS, INPT, Toulouse, France 4 Universite Moulay Ismail, Meknes, Morocco 5 Universite de Toulouse, Laboratoire de Genie Chimique UMR 5503 (CNRS/INPT/UPS), INP de Toulouse/ENSAT, Castanet-Tolosan Cedex, France 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-contain- ing molecule with interesting antimicrobial activities towards various multidrug-resistant micro-organ- isms. 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. Keywords Abstract antimicrobial activity, hydroxamic acid, Streptomyces, structure elucidation, During screening for potentially antimicrobial actinobacteria, a highly taxonomy. antagonistic strain, designated WAB9, was isolated from a Saharan soil of Algeria. A polyphasic approach characterized the strain taxonomically as a Correspondence member of the genus Streptomyces. The strain WAB9 exhibited a broad Nasserdine Sabaou, Laboratoire de Biologie spectrum of antimicrobial activity toward various multidrug-resistant micro- des Systemes Microbiens, Ecole Normale organisms. A PCR-based assay of genomic potential for producing bioactive Superieure de Kouba, Alger 16050, Algeria. E-mail: [email protected] 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 1H and 13C doi:10.1111/lam.12412 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. Introduction respect to their effects against pathogenic strains and have led to the discovery of a large number of novel active Actinobacteria are a group of ubiquitous Gram-positive compounds of considerable value (Solecka et al. 2012). bacteria with a percentage of guanine–cytosine higher However, the present context of both a decline in the dis- than 55%, and most of them produce mycelia. Because of covery of new antibiotics and an increase in drug-resis- their ability to provide a broad range of bioactive com- tant pathogens makes the screening for new antibiotic- pounds, these micro-organisms have attracted much producing Streptomyces essential. interest. Members of this group, in particular those One of the strategies for enhancing the likelihood of belonging to the genus Streptomyces, are considered as the obtaining particularly interesting isolates and secondary most important producers of bioactive molecules. There- metabolites is to analyse extreme habitats (Santhanam fore, Streptomyces have been thoroughly investigated with et al. 2012), such as arid Saharan soils. Previous surveys on the ecological distribution of Actinomycetes in Alge- Table 1 Antagonistic properties of the strain WAB9 against various multidrug-resistant micro-organisms rian Saharan soils have already demonstrated their appre- ciable biodiversity (Sabaou et al. 1998) and permitted Target micro-organism new species and new antibiotics to be found (Boubetra (antibiotic resistance pattern*) Activity† (mm) et al. 2013; Meklat et al. 2013). Bacillus subtilis ATCC 6633 (NEO) 39 Hydroxamic acids (bearing the functional group N- Staphylococcus aureus S1 28 hydroxy amide) are one such interesting class of molecule (CAR, GEN, K, NEO, OLE, SPI, VAN) produced by many Streptomyces species (Dimkpa et al. Enterobacter cloacae E13 (AMC, ATM, CEP, 29 2008; Kodani et al. 2013). Their low toxicities in general, CTX, FEP, FOX, GEN, PIP, TCC, TIC, TOB) their weak acid properties and their ability for complex- Escherichia coli E52 (ATM, CAZ, CEP, CTX, 35 ing transition metal ions have resulted in these molecules FEP, GEN, PIP, TIC, TOB) Klebsiella pneumoniae K44 (AMX, AN, CF, 29 receiving considerable attention for broad therapeutic and CRO, CTX, CXM, GEN, K, MZ, SSS, TIC) industrial applications (Vanjari and Pande 2003; Rho Pseudomonas aeruginosa IPA1 (AMX, CAR, 29 et al. 2006; Jahangirian et al. 2011). Among their numer- GEN, NEO, SPI, SSS, VAN) ous properties, hydroxamic acids and derivatives have Salmonella enterica E32 (ATM, CAZ, CEP, 16 been largely reported as effective antibacterial and anti- CTX, FEP, GEM, PIP, TIC, TOB) fungal agents (Li et al. 2003; Pepeljnjak et al. 2005). These Fusarium culmorum (CHX, ITR, NYS, TIZ) 39 activities are connected with the ability of hydroxamic Fusarium moniliforme (AMB, CHX, NYS, TIZ) 29 Fusarium sporotrichoides 20 acids to potently and selectively inhibit a range of (AMB, CHX, ITR, NYS, TIZ, TER) enzymes that are vital for the survival of bacteria, such as Fusarium graminearum (CHX, NYS, TIZ) 25 various metalloproteinases, urease, cyclooxygenases and Fusarium oxysporum f. sp. lini (ITR,TIZ) 25 peroxidase (Muri et al. 2004). F. oxysporum f. sp. albedinis 26 Recently, exploration of microbial antibiotic potential (AMB, CHX, ITR, NYS, TIZ, TER) has focused on the screening of polyketide synthase (PKS) Fusarium proliferatum (CHX, ITR, NYS, TIZ) 22 and nonribosomal peptide synthetase (NRPS) genes. This Fusarium equiseti (CHX, TIZ) 30 Aspergillus carbonarius (CHX, NYS) 33 exploration approach seems applicable for hydroxamic Aspergillus niger (AMB, CHX, NYS, TIZ) 25 acid-containing molecules, since these molecules are Aspergillus flavus (TIZ) 26 already known to be synthesized through NRPS-depen- Aspergillus parasiticus (AMB, CHX, ITR, NYS, TIZ) 20 dent or independent pathways (Barry and Challis 2009; Penicillium glabrum (CHX) 38 Oves-Costales et al. 2009). Penicillium expansum 37 Here, we describe the isolation of a highly antagonistic Umbelopsis ramanniana (CHX, ITR, TIZ, TER) 36 Streptomyces strain, designated WAB9, from a Saharan soil Candida albicans IPA 200 (NYS, ITR, TIZ, CHX, TER) 15 Saccharomyces cerevisiae ATCC 4226 34 sample and its identification by conventional and molecu- lar methods, together with production and structure eluci- AMC, amoxicillin + clavulanic acid; AMX, amoxicillin; AN, amikacin; dation of the corresponding bioactive compound, which ATM, aztreonam; C, chloramphenicol; CAR, carbenicillin; CAZ, ceftazi- was found to be a new hydroxamic acid-containing antibi- dime; CFP, cefpirome; CRO, ceftriaxone; CTX, cefotaxime; CXM, ce- otic. The minimum inhibitory concentrations (MICs) of furoxime; FEP, cefepime; FOX, cefoxitin; GEN, gentamicin; K, kanamycin; MZ, mezlocillin; NEO, neomycin; OLE, oleandomycin PIP, this antibiotic were also evaluated on a set of various mul- piperacillin; SPI; spiramycin; SSS, sulfamide; TCC, ticarcillin + clavulan- tidrug-resistant bacteria, filamentous fungi and yeasts. ic acid; TIC, ticarcillin; TOB, tobramycin; VAN, vancomycin; AMB, amphotericin B; CHX, cycloheximide; ITR, itraconazole; NYS, nystatin; TIZ, thioconazole; TER, terbinafine. Results and discussion *The antibiotic resistance patterns were evaluated in house as The strain WAB9 was isolated by plating a 2 : 10 serial described by Touati et al. (2006). dilution of the soil sample of Bechar on chitin-vitamin †Activity estimated by measuring the length of inhibition between agar medium supplemented with selective antibiotics. Actinomycetes and target micro-organisms. This strain was found in only a single small colony, which shows it rarity. the targeted bacteria, filamentous fungi and yeasts (dis- tance of inhibition ranged between 15 and 35 mm). Sal- monella enterica and Candida albicans were the least Antagonistic properties and detection of PKS and NRPS sensitive (distance of inhibition <20 mm). The use of sequences antibiotics as selective agents in the isolation of actino- The strain WAB9 exhibited a broad spectrum of antimi- bacteria has already been mentioned as a successful crobial activity (Table 1), since it was active against all method for the isolation of interesting strains originating from Saharan soils (Sabaou et al. 1998) and has permitted mannitol, rhamnose, salicine, xylose, histidine, phenylala- novel species and antibiotics to be discovered (Boubetra nine, proline, starch and xanthine, but not melibiose, raf- et al. 2013; Meklat et al. 2013). finose or sucrose. The strain was able to grow in the Á Only the PKS-II gene was detected through the PCR- presence of phenol (0 1% w/v), penicillin (10 UI) and rif- À based screening of genomic potential for producing bio- ampicin (50 lgml 1),