Saccharothrix ghardaiensis sp. nov., an actinobacterium isolated from Saharan soil.

The taxonomic position of a new Saccharothrix strain, designated MB46T, isolated from a Saharan soil sample collected in Mzab region (Ghardaïa province, South Algeria) was established following a polyphasic approach. The novel microorganism has morphological and chemical characteristics typical of the members of the genus Saccharothrix and formed a phyletic line at the periphery of the Saccharothrix espanaensis subcluster in the 16S rRNA gene dendrograms. Results of the 16S rRNA gene sequence comparisons revealed that strain MB46T shares high degrees of similarity with S. espanaensis DSM 44229T (99.2%), Saccharothrix variisporea DSM 43911T (98.7%) and Saccharothrix texasensis NRRL B-16134T (98.6%). However, the new strain exhibited only 12.5-17.5% DNA relatedness to the neighbouring Saccharothrix spp. On the basis of phenotypic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridizations, strain MB46T is concluded to represent a novel species of the genus Saccharothrix, for which the name Saccharothrix ghardaiensis sp. nov. (type strain MB46T = DSM 46886T = CECT 9046T) is proposed.

Planomonospora algeriensis sp. nov., an actinobacterium isolated from a Saharan soil of Algeria.

A filamentous actinobacterium, designated strain PM3T, was isolated from a Saharan soil sample collected from Béni-Abbès, Béchar (South-West Algeria). A polyphasic taxonomic study was carried out to establish the status of strain PM3T. The isolate was found to have morphological and chemotaxonomical properties associated with members of the genus Planomonospora. The new isolated microorganism developed cylindrical sporangia arranged in double parallel rows on aerial mycelium, each one containing a motile single sporangiospore. The cell wall of the strain was found to contain meso-diaminopimelic acid. Whole-cell hydrolysates were found to contain madurose, glucose, mannose and ribose. The predominant menaquinone was identified as MK-9(H2) (69.6%). The polar lipids detected were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylhydroxyethanolamine and glucosamine-containing lipids. The major fatty acids were found to be C17:1ω9c (38.6%) and C17:0 (24.2%). Results of 16S rRNA gene sequence comparison revealed that strain PM3T shared a high degree of 16S rRNA gene sequence similarity with Planomonospora sphaerica DSM 44632T (99.3%), Planomonospora parontospora subsp. parontospora DSM 43177T (99.2%) and P. parontospora subsp. antibiotica DSM 43869T (99.0%). DNA-DNA hybridization values between strain PM3T and the type strains of the closely related species were between 58.4 and 70.1%. The combination of phylogenetic analysis, DNA-DNA relatedness data, phenotypic characteristics and chemotaxonomic data support the conclusion that strain PM3T represents a novel species of the genus Planomonospora, for which the name Planomonospora algeriensis sp. nov. is proposed. The type strain is PM3T (=DSM 46752T = CECT 9047T).

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

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 13368T 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 1H and 13C 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 (MBIC50) of this compound showed significant activity against multidrug-resistant S. aureus with 15-30 and 10-15 µg/mL, respectively.

Streptosporangium becharense sp. nov., an actinobacterium isolated from desert soil.

The taxonomic position of a novel actinobacterium, strain SG1T, isolated from a Saharan soil sample collected from Béni-Abbès, Béchar (south-west Algeria), was established by using a polyphasic approach. The micro-organism had morphological and chemical features that were consistent with its classification in the genus Streptosporangium. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose and glucose, but not madurose. The predominant menaquinones were MK-9(H2) and MK-9(H4). The polar lipid profile contained diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylhydroxymethylethanolamine, phosphatidylhydroxyethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The predominant cellular fatty acids were C17 : 1ω8c, iso-C16 : 0, 10-methyl C17 : 0, C18 : 1ω9c and C17 : 0. 16S rRNA gene sequence similarity analysis supported the classification of the isolate in the genus Streptosporangium and indicated that it was related most closely to 'Streptosporangium subfuscum' DSM 46724 (99.7 % similarity), Streptosporangium pseudovulgare DSM 43181T (98.7 %), Streptosporangium fragile DSM 43847T (98.6 %) and Streptosporangium sandarakinum DSM 45763T (98.5 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain SG1T formed a cluster with its closest relative 'S. subfuscum' DSM 46724. However, DNA-DNA relatedness as well as physiological and chemotaxonomical analyses showed that strain SG1T could be differentiated from its closest phylogenetic relatives. Therefore, it is proposed that strain SG1T should be classified as representing a novel species in the genus Streptosporangium, for which the name Streptosporangiumbecharense sp. nov. is proposed. The type strain is SG1T (=DSM 46887T=CECT 8961T).

Actinophytocola algeriensis sp. nov., an actinobacterium isolated from Saharan soil.

During our investigations of new actinobacterial taxa, a novel actinobacterial strain, designated MB20T, was isolated from a Saharan soil sample, collected in the Mzab region (Ghardaïa province, southern Algeria). In order to reveal its taxonomic position, the novel strain was characterized following a polyphasic taxonomic approach. It was noticed that strain MB20T produced white, branched and fragmented substrate mycelium with no aerial mycelium on most of the media tested. Chemotaxonomic and phylogenetic studies clearly demonstrated that strain MB20T belonged to the family Pseudonocardiaceae and was closely related to the genus Actinophytocola. Cell-wall hydrolysates contained meso-diaminopimelic acid but not glycine, and whole-cell hydrolysates contained galactose, glucose and ribose. The diagnostic phospholipid was phosphatidylethanolamine. Mycolic acids were not detected while the predominant fatty acid was found to be iso-branched hexadecanoate (iso-C16 : 0). The major menaquinone was MK-9(H4). Results of the 16S rRNA gene sequence comparison revealed that strain MB20T shared the highest degree of similarity with Actinophytocola gilvus DSM 45828T (98.5 %), Actinophytocola corallina DSM 45659T (98.0 %) and Actinophytocola timorensis DSM 45660T (97.5 %). However, DNA-DNA hybridization studies showed only 32.9 % similarity with A. timorensis, 23.7 % similarity with A. gilvus and 17.9 % similarity with A. corallina. On the basis of phenotypic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridization, strain MB20T was revealed to be a representative of a novel species of the genus Actinophytocola, for which the name Actinophytocola algeriensis sp. nov. (type strain MB20T =DSM 46746T =CECT 8960T) is proposed.

Actinomadura adrarensis sp. nov., an actinobacterium isolated from Saharan soil.

A novel actinobacterial strain, designated ACD12T, 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(H6). The fatty acid profile was characterized by the presence of C16 : 0, C17 : 0, C15 : 0, C18 : 0, C18 : 1 cis9 and iso-C16 : 0. Results of 16S rRNA gene sequence comparisons revealed that strain ACD12T shared the highest degree of 16S rRNA gene sequence similarity with Actinomadura sputi DSM 45233T (98.3 %) and Actinomadura hallensis DSM 45043T (97.8 %). All tree-making algorithms used also supported strain ACD12T forming a distinct clade with its most closely related species. In addition, DNA-DNA hybridization indicated only 39.8 % relatedness with A. sputi DSM 45233T and 18.7 % relatedness with A. hallensis DSM 45043T. 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 ACD12T (=DSM 46745T =CECT 8842T).

Actinomadura algeriensis sp. nov., an actinobacterium isolated from Saharan soil.

During the course of a screening programme for new taxa of actinobacteria, a strain designated ACD1(T), was isolated from a Saharan soil in the Hoggar region (Algeria). The taxonomic position of this strain was determined using a polyphasic taxonomic approach. The strain was observed to form extensively branched, non-fragmenting substrate mycelium, and aerial mycelium with straight to flexuous, hooked and irregular spirals (1-2 turns) forming short chains of spores. The diamino acid present in the cell wall is meso-diaminopimelic acid. Galactose, glucose, madurose, mannose and ribose occur in whole-cell hydrolysates. The diagnostic phospholipids detected were diphosphatidylglycerol and phosphatidylinositol. The major menaquinones were identified as MK-9 (H4) and MK-9 (H2). The major fatty acids were found to be C16:0, C18:1 cis9, iso-C16:0 and 10-methyl C18:0. Phylogenetic analysis based on the 16S rRNA gene showed that the strain belongs to the genus Actinomadura, and is closely related to Actinomadura sediminis DSM 45500(T) (98.5 % similarity) and Actinomadura cremea subsp. cremea DSM 43676(T) (98.3 % similarity). However, DNA-DNA hybridization revealed only 48.0 % relatedness with A. sediminis DSM 45500(T) and 33.2 % relatedness with A. cremea subsp. cremea DSM 43676(T). The combined phenotypic and genotypic data showed that the strain represents a novel species of the genus Actinomadura, for which the name Actinomadura algeriensis sp. nov. is proposed, with the type strain ACD1(T) (= DSM 46744(T) = CECT 8841(T)).

Isolation, Identification and Screening of Saharan Actinomycete Strain Streptomyces fimbriatus AC31 Endowed with Antimicrobial Activity.

The increasing global public health concern of antimicrobial resistance (AMR) necessitates exploration of natural antimicrobial agents as potential alternatives. This study aimed to investigate antimicrobial activities of Saharan actinomycetes, with specific focus on the strain Streptomyces fimbriatus AC31, that holds promising potential as an alternative to combat AMR. In this context, 32 actinomycetes were isolated from El Atteuf (Ghardaïa), Algeria. Isolates obtained were characterized morphologically and biochemically. Screened isolate was identified by 16S rRNA gene sequencing. Classification of actinomycete isolates was carried out by UPGMA (Unweighted Pair Group Method with Arithmetic Mean). Then, they were screened for their antimicrobial activity by cross-streak method. Identification of 32 isolates revealed 5 genera: Streptomyces (65.63%), Nocardia (9.38%), Streptosporangium (9.38%), Nocardiopsis (9.38%) and Actinomadura (6.25%). According to the biochemical and physiological characteristics, UPGMA classified the isolates in 4 phenons. A number of 24 (75.00%) isolates were active against Gram-positive bacteria, 21 (65.63%) isolates were effective against Gram-negative bacteria, and 25 (78.13%) isolates inhibited Candida albicans. Screened strain Streptomyces fimbriatus AC31 showed highest antagonistic activity and revealed an inhibition zones of 41, 38, 41, 42, and 44 mm, against B. subtilis (ATCC 6633), E. coli (ATCC 8739), S. typhimurium (ATCC 13331), S. aureus (ATCC 6538) and C. albicans (ATCC 10231), respectively. Phylogenetic identification of the AC 31 isolate using 16S rRNA gene sequence showed similarity of 100% with Streptomyces fimbriatus NBRC 15411T. Actinomycete isolates characterized in this study were endowed with antimicrobial activity against various pathogenic microorganisms that could be used efficiently in developing new antimicrobial substances.