Actinobacteria Associated with Vineyard Soils of Algeria: Classification, Antifungal Potential Against Grapevine Trunk Pathogens and Plant Growth-Promoting Features.

Grapevine trunk diseases (GTDs) are among the most destructive diseases of vineyards worldwide, including Algeria. In the fungal complex involved in GTD symptoms, referred as grapevine trunk-pathogens, Paeomoniella chlamydospora and Phaeoacremonium minimum have a determining infecting role as pioneer fungi. Due to the lack of efficiency of conventional disease management practices, a search for alternative strategies, such as biocontrol, is needed. Taking the approach of looking for biocontrol candidates in the environment surrounding the plant, the present study explored actinobacteria diversity within vineyard soils of six grape-producing regions in Algeria. Based on their 16S rRNA gene sequence, identification and phylogenic analysis were performed on the 40 isolates of actinobacteria obtained. Forty percent of strains were attached to Streptomyces, including two evidenced new species, and 32.5% were affiliated to Saccharothrix. The other less represented genera were Actinoplanes, Nocardia, Nocardiopsis, Lentzea, Nonomuraea, Promicromonospora, Saccharopolyspora and Streptosporangium. Screening based on antagonistic and plant growth promotion (PGP) abilities of the strains showed that 47.5% of the isolates exhibited appreciable antagonistic activities against both Pa. chlamydospora and Pm. minimum, with the two best strains being Streptomyces sp. Ms18 and Streptomyces sp. Sb11. Screening for plant growth promoting properties demonstrated that majority of the strains were able to produce indole acetic acid, siderophores, ammonia, ACC deaminase, cellulase and amylase, and fix N2. Through a PGP-traits-based cluster analysis, the most interesting strains were highlighted. Taking into account both antagonistic and PGP properties, Streptomyces sp Sb11 was selected as the most promising candidate for further evaluations of its efficiency in a GTDs context.

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).

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.

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).

Streptosporangium saharense sp. nov., an actinobacterium isolated from Saharan soil.

A novel actinobacterium, designated strain SG20T, was isolated from a Saharan soil sample collected from Béni-isguen (Mzab), Ghardaïa province, southern Algeria. The micro-organism developed small roundish sporangia on aerial mycelium that were sessile or carried by very short sporangiophores. The cell-wall peptidoglycan contained meso-diaminopimelic acid and the whole-cell sugars comprised glucose, ribose and mannose, but madurose was not detected. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-9(H2). The major fatty acids were iso-C16 : 0 and C16 : 0. The phospholipids detected were diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine and unknown lipids. The phenotypic and chemotaxonomic characteristics of the novel strain resembled those of recognized members of the genus Streptosporangium. Moreover, phylogenetic analysis based on a 16S rRNA gene sequence generated from the strain identified its closest relative as Streptosporangium jomthongense BCC 53154T (98.5 % similarity), which produces single spores on aerial mycelium, but no sporangia. In hybridization experiments, the DNA-DNA relatedness values recorded between strain SG20T and S. jomthongense DSM 46822T fell well below 70 %. On the basis of phenotypic and genotypic data, strain SG20T can be distinguished as representing a novel species of the genus Streptosporangium, for which the name Streptosporangium saharense sp. nov. is proposed. The type strain is SG20T ( = DSM 46743T = CECT 8840T).

Saccharothrix isguenensis sp. nov., an actinobacterium isolated from desert soil.

A novel actinobacterial strain, designated MB27T, was isolated from a Saharan soil sample collected in Mzab region (Ghardaïa province, South Algeria). Strain MB27T was characterized following a polyphasic taxonomic approach. This strain produced a branched and fragmented substrate mycelium, which was found to have a yellowish orange colour. A white scanty aerial mycelium was produced on most media tested. Chemotaxonomic and phylogenetic studies clearly demonstrated that strain MB27T belongs to the family Pseudonocardiaceae and is closely related to the genus Saccharothrix. Cell-wall hydrolysates contained meso-diaminopimelic acid but not glycine, and whole-cell hydrolysates contained galactose, glucose, ribose and small amounts of mannose and rhamnose. The detected phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. Mycolic acids were not detected while the predominant fatty acid was iso-branched hexadecanoate (iso-C16 : 0). The major menaquinone was MK-9(H4). Results of 16S rRNA gene sequence comparisons revealed that strain MB27T shairs the highest degree of similarity with Saccharothrix ecbatanensis DSM 45486T (99.8%), Saccharothrix hoggarensis DSM 45457T (99.3 %), Saccharothrix longispora DSM 43749T (98.6 %) and Saccharothrix yanglingensis DSM 45665T (98.6 %). However, it exhibited only 11-42 % DNA-DNA relatedness to the neighbouring Saccharothrixspecies. On the basis of phenotypic characteristics, 16S rRNA gene sequence comparisons and DNA-DNA hybridization, strain MB27T is shown to represent a novel species of the genus Saccharothrix, for which the name Saccharothrix isguenensis sp. nov. (type strain MB27T=DSM 46885T=CECT 9045T) is proposed.

Thermoactinomyces khenchelensis sp. nov., a filamentous bacterium isolated from soil sediment of a terrestrial hot spring.

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)).

Actinokineospora mzabensis sp. nov., a novel actinomycete isolated from Saharan soil.

A novel actinomycete strain, designated PAL84, was isolated from a Saharan soil sample collected from Béni-Isguen, Ghardaïa (South of Algeria). This strain was studied for its taxonomic position using a polyphasic approach and was identified as a member of the genus Actinokineospora. Phylogenetic analysis showed that strain PAL84 had 16S rRNA gene sequence similarities with members of the genus Actinokineospora ranging from 96.2 % (Actinokineospora inagensis DSM 44258(T)) to 97.8 % (Actinokineospora baliensis NBRC 104211(T)). The strain was observed to produce pinkish-purple aerial mycelium and purplish red substrate mycelium, which fragmented readily into chains of non-motile elements. The optimum growth temperature and pH were found to be 25-30 °C and 5.0-7.0, respectively. The cell-wall hydrolysate of strain PAL84 was found to contain meso-diaminopimelic acid and the diagnostic whole-cell sugars were identified as arabinose and galactose. The predominant menaquinone was identified as MK-9 (H4). The major fatty acids were found to be iso-C16:0, iso-C15:0, iso-C16:1 H and iso-C16:0 2OH. The diagnostic phospholipid detected was phosphatidylethanolamine. The genotypic and phenotypic data show that the strain represents a novel species of the genus Actinokineospora, for which the name Actinokineospora mzabensis sp. nov. is proposed, with the type strain PAL84(T) (=DSM 45961(T) = CECT 8578(T)).

Bounagaea algeriensis gen. nov., sp. nov., an extremely halophilic actinobacterium isolated from a Saharan soil of Algeria.

A novel halophilic actinobacterium strain, designated H8(T), was isolated from a Saharan soil sample collected in El-Goléa, South Algeria. Strain H8(T) was identified as representing a new genus using a polyphasic taxonomic approach. Phylogenetic analysis revealed that strain H8(T) shared the highest degree of 16S rRNA gene sequence similarity with 'Mzabimyces algeriensis' DSM 46680(T) (93.0 %), Saccharopolyspora ghardaiensis DSM 45606(T) (91.2 %), Halopolyspora alba DSM 45976(T) (90.8 %) and Actinopolyspora mortivallis DSM 44261(T) (90.0 %). The strain was found to grow optimally at 28-35 °C, at pH 6.0-7.0, and in the presence of 15-25 % (w/v) NaCl. The substrate mycelium was observed to be well developed and fragmented in liquid medium and on solid medium. The aerial mycelium was observed to be moderately abundant and to form long chains with non-motile, smooth-surfaced and ovoid or spherical spores at maturity. The cell wall of strain H8(T) was found to contain meso-diaminopimelic acid. The whole-cell hydrolysates were found to mainly contain arabinose and galactose. The diagnostic phospholipid detected was phosphatidylcholine, and MK-9(H4), MK-9(H2) and MK-10(H2) were found to be the predominant menaquinones. The major cellular fatty acids were determined to be anteiso-C17:0 and iso-C15:0. The genomic DNA G+C content of strain H8(T) was determined to be 71.3 mol%. The genotypic and phenotypic data showed that the strain represents a novel genus and species, for which the name Bounagaea algeriensis gen. nov., sp. nov. is proposed, with the type strain H8(T) (=DSM 45966(T) = CECT 8470(T)).

Aspergillus section Flavi and aflatoxins in Algerian wheat and derived products.

Wheat and its derivatives are a very important staple food for North African populations. The aim of this study was to analyze populations of Aspergillus section Flavi from local wheat based on aflatoxins (AFs), cyclopiazonic acid (CPA) and sclerotia production, and also to evaluate AFs-contaminated wheat collected from two different climatic regions in Algeria. A total of 108 samples of wheat were collected during the following phases: pre-harvest, storage in silos and after processing. The results revealed that among the Aspergillus species isolated, those belonging to section Flavi were predominant. Of the 150 strains of Aspergillus section Flavi isolated, 144 were identified as Aspergillus flavus and 6 as Aspergillus tamarii. We showed that 72% and 10% of the A. flavus strains produced AFs and CPA, respectively. Among the 150 strains tested, 60 produced amounts of AFB1 ranging from 12.1 to 234.6 microg/g of CYA medium. Also, we showed that most strains produced large sclerotia. AFB1was detected by HPLC in 56.6% of the wheat samples and derived products (flour, semolina and bran) with contamination levels ranging from 0.13 to 37.42 microg/kg.