The actinobacterium strain ABH26 closely related to Saccharothrix xinjiangensis, isolated from an Algerian Saharan soil sample, exhibited highly antagonist activity against Gram-positive bacteria, yeasts and filamentous fungi. Its ability to produce antimicrobial compounds was investigated using several solid culture media. The highest antimicrobial activity was obtained on Bennett medium. The antibiotics secreted by strain ABH26 on Bennett medium were extracted by methanol and purified by reverse-phase HPLC using a C18 column. The chemical structures of the compounds were determined after spectroscopic (1H NMR, 13C NMR, 1H-1H COSY and 1H-13C HMBC spectra), and spectrometric (mass spectrum) analyses. Two new cyanogriside antibiotics named cyanogriside I (1) and cyanogriside J (2), were characterized along with three known caerulomycins, caerulomycin A (3), caerulomycin F (4) and caerulomycinonitrile (5). This is the first report of cyanogrisides and caerulomycins production by a member of the Saccharothrix genus. The minimum inhibitory concentrations (MIC) of these antibiotics were determined against pathogenic microorganisms.
A new strain of actinobacteria, designated ACD1, was isolated from a Saharan soil sample in the Hoggar region (Algeria). Morphological study led to this strain being classified as a member of the Actinomadura genus. Phylogenetic analysis based on the 16S rRNA gene showed that the strain is closely related to Actinomadura sediminis DSM 45500(T) (98.5% sequence similarity). Furthermore, strain ACD1 presented a strong activity against mycotoxigenic and phytopathogenic fungi, including Aspergillus and Fusarium strains, and other pathogenic microorganisms. The kinetics of antimicrobial activity were investigated on ISP-2, Bennett and TSB media. Four solvents (n-hexane, dichloromethane, ethyl acetate and n-butanol) were used for the extraction of the produced antibiotic. The highest antimicrobial activity was obtained using the butanolic extract from the ISP-2 medium after seven days of fermentation culture. The active antibiotic was purified by reverse-phase HPLC using a C18 column. The UV-visible and mass spectra were determined. The minimum inhibitory concentrations (MIC) of this antibiotic were determined against pathogenic microorganisms.
A novel actinobacterial strain, designated ACD12 T , was isolated from a Saharan soil sample collected from Adrar province, southern Algeria. A polyphasic study was carried out to establish the taxonomic position of this strain. Strain ACD12T was observed to form extensively branched substrate mycelia. Aerial mycelium was absent or was weakly produced on all media tested, while spore chains were short with a hooked and irregular spiral form (2-3 turns). The dominant diaminopimelic acid isomer in the cell wall was meso-diaminopimelic acid. Glucose, ribose, galactose, mannose and madurose occured in whole-cell hydrolysates. The major phospholipid was diphosphatidylglycerol and phosphatidylinositol. The predominant menaquinone was MK-9 (H 6 ). The fatty acid profile was characterized by the presence of C 16 : 0 , C 17 : 0 , C 15 : 0 , C 18 : 0, C 18 : 1 cis9 and iso-C 16 : 0 . Results of 16S rRNA gene sequence comparisons revealed that strain ACD12 T shared the highest degree of 16S rRNA gene sequence similarity with Actinomadura sputi DSM 45233 T (98.3 %) and Actinomadura hallensis DSM 45043 T (97.8 %). All tree-making algorithms used also supported strain ACD12 T forming a distinct clade with its most closely related species. In addition, DNA-DNA hybridization indicated only 39.8 % relatedness with A. sputi DSM 45233 T and 18.7 % relatedness with A. hallensis DSM 45043 T . The combined phenotypic and genotypic data show that the novel isolate represents a novel species of the genus Actinomadura, for which the name Actinomadura adrarensis sp. nov., is proposed, with the type strain ACD12 T (=DSM 46745 T =CECT 8842 T ).The genus Actinomadura, a member of the family Thermomonosporaceae, was proposed by Lechevalier & Lechevalier (1968). The strains of species of the genus Actinomadura have been principally isolated from soil (Lu et al., 2003;Quintana et al., 2003; Ara et al., 2008). However, some species have been isolated from patients, such as Actinomadura sputi (Yassin et al., 2010). This genus is of great importance in several domains, including the production of new bioactive metabolites active against pathogenic microorganisms (Euanorasetr et al., 2015). Species of the genus Actinomadura produce an extensively branched non-fragmenting substrate mycelium and, generally, aerial mycelium is moderately developed or absent. Spore chains are short and differentiate into straight, spiral or hooked forms. The strains of species of the genus Actinomadura are characterized by the presence of type III cell walls (meso-diaminopimelic acid without glycine). Whole-cell hydrolysates contain madurose as the diagnostic sugar. Cell membranes contain diphosphatidylglycerol and phosphatidylinositol as the diagnostic phospholipids, and MK-9(H 4 ) and MK-9(H 6 ) as the major menaquinones (Lechevalier et al., 1977;Kroppenstedt et al., 1990;Wink et al., 2003;Cook et al., 2005). Many species of the genus Actinomadura have been described in recent years and, at the time of writing, the genus comprises 53 species with validly published...
A novel thermophilic filamentous bacterium, designated strain T36(T), was isolated from soil sediment sample from a hot spring source collected in Khenchela province, Algeria. Strain T36(T) was identified as a member of the genus Thermoactinomyces by a polyphasic approach. Strain T36(T) was observed to form white aerial mycelium and non-coloured to pale yellow substrate mycelium, both producing endospores, sessile or borne by short sporophores. The optimum growth temperature and pH were found to be 37-55 °C and 7.0-9.0, respectively and the optimum NaCl concentration for growth was found to be 0-7 % (w/v). The diagnostic diamino acid in the cell wall peptidoglycan was identified as meso-diaminopimelic acid. The predominant menaquinone of strain T36(T) was identified as MK-7 (H0). The major fatty acids were found to be iso-C15:0 and iso-C17:0. The phospholipids detected were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphoglycolipid. The chemotaxonomic properties of strain T36(T) are consistent with those shared by members of the genus Thermoactinomyces. 16S rRNA gene sequence analysis indicated that the sequence similarities between strain T36(T) and Thermoactinomyces species with validly published names were less than 98 %. Based on the combined genotypic and phenotypic evidence, it is proposed that strain T36(T) should be classified as representative of a novel species, for which the name Thermoactinomyces khenchelensis sp. nov. is proposed. The type strain is T36(T) (=DSM 45951(T) = CECT 8579(T)).
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