Noureddine Bouras

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.

Effect of amino acids containing sulfur on dithiolopyrrolone antibiotic productions by Saccharothrix algeriensis NRRL B‐24137

Aims:  To study the effect of sulfur‐containing amino acids (L‐cysteine, L‐cystine, L‐methionine and DL‐ethionine) on the production of dithiolopyrrolone antibiotics by Saccharothrix algeriensis NRRL B‐24137.

Dithiolopyrrolone Antibiotic Formation Induced by Adding Valeric Acid to the Culture Broth of Saccharothrix algeriensis

Three new antibiotics were isolated from the fermentation broth of Saccharothrix algeriensis NRRL B-24137 and characterized as the dithiolopyrrolone derivatives valerylpyrrothine (1), isovalerylpyrrothine (2), and formylpyrrothine (3) as well as the known antibiotic aureothricin. The production of the dithiolopyrrolone derivatives was induced by adding valeric acid to the culture medium. The compounds exhibited moderate antimicrobial activity in vitro.

Saccharothrix hoggarensis sp. nov., an actinomycete isolated from Saharan soil

An actinomycete, designated SA181(T), was isolated from Saharan soil in the Hoggar region (south Algeria) and was characterized taxonomically by using a polyphasic approach. The morphological and chemotaxonomic characteristics of the isolate were consistent with the genus Saccharothrix, and 16S rRNA gene sequence analysis confirmed that strain SA181(T) was a novel member of the genus Saccharothrix. DNA-DNA hybridization values between strain SA181(T) and its closest phylogenetic neighbours, the type strains of Saccharothrix longispora, Saccharothrix texasensis and Saccharothrix xinjiangensis, were clearly below the 70 % threshold. The genotypic and phenotypic data showed that the isolate represents a novel species of the genus Saccharothrix, for which the name Saccharothrix hoggarensis sp. nov. is proposed, with the type strain SA181(T) ( = DSM 45457(T)  = CCUG 60214(T)).

Actinopolyspora mzabensis sp. nov., a halophilic actinomycete isolated from an Algerian Saharan soil.

A halophilic actinomycete strain, designated H55(T), was isolated from Saharan soil sampled in the Mzab region (Ghardaïa, southern Algeria) and was characterized in a taxonomic study using a polyphasic approach. The cell wall was determined to contain meso-diaminopimelic acid and the characteristic whole-cell sugars were arabinose and galactose. The predominant menaquinones were found to be MK-10(H4) and MK-9(H4). The predominant cellular fatty acids were determined to be anteiso-C17 : 0, iso-C16 : 0 and iso-C15 : 0. The diagnostic phospholipid detected was phosphatidylcholine. The morphological and chemotaxonomic characteristics of the strain were consistent with those of members of the genus Actinopolyspora, and 16S rRNA gene sequence analysis confirmed that strain H55(T) was a member of this genus. DNA-DNA hybridization values between strain H55(T) and the type strains of the nearest species of the genus Actinopolyspora, Actinopolyspora erythraea and A. alba, were clearly below the 70 % threshold. The genotypic and phenotypic data showed that the organism represents a novel species of the genus Actinopolyspora, for which the name Actinopolyspora mzabensis sp. nov. is proposed, with the type strain H55(T) ( = DSM 45460(T) = CCUG 62965(T)).

Saccharopolyspora ghardaiensis sp. nov., an extremely halophilic actinomycete isolated from Algerian Saharan soil

A novel halophilic actinomycete, strain designated H53T, was isolated from a Saharan soil sample collected from Chaâbet Ntissa, Béni-isguen, Ghardaïa (South of Algeria) and was characterized taxonomically by means of polyphasic approach. Optimal growth was found to occur at 30–35 °C, pH 6–7 and in the presence of 15–25% (w/v) NaCl. The strain was observed to produce abundant aerial mycelium, which formed long chains of rod-shaped spores at maturity, and well developed and fragmented substrate mycelium. The cell wall was determined to contain meso-diaminopimelic acid; the diagnostic whole-cell sugars were arabinose and galactose. The predominant menaquinones were found to be MK-9(H4) and MK-9(H6). The predominant cellular fatty acids were determined to be iso- and anteiso-C17:0, iso-C15:0, and cis9 iso-C17:1. The diagnostic phospholipid detected was phosphatidylcholine. The morphological and chemotaxonomic characteristics of the strain were consistent with those of members of the genus Saccharopolyspora. Phylogenetic analyses on the basis of the 16S ribosomal RNA (rRNA) gene sequence showed that this strain formed a distinct phyletic line within the radiation of the genus Saccharopolyspora. The 16S rRNA sequence similarities between strain H53T and other members of the genus Saccharopolyspora ranged from 92.1 to 94.3%. The DNA G+C content of strain H53T was 72.6%. The genotypic and phenotypic data showed that the strain H53T represents a novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora ghardaiensis sp. nov. is proposed, with the type strain H53T (=DSM 45606T=CCUG 63370T=CECT 8304T).

Saccharothrix saharensis sp. nov., an actinomycete isolated from Algerian Saharan soil.

The taxonomic position of a novel actinomycete, strain SA152(T), isolated from a sample of Algerian Saharan soil, was determined using a polyphasic taxonomic approach. The strain produced abundant aerial mycelium and fragmented substrate mycelium on most media tested. Chemotaxonomically and phylogenetically, the strain was related to the members of the genus Saccharothrix. Results of 16S rRNA gene sequence comparison revealed that strain SA152(T) shared the highest degree of 16S rRNA gene sequence similarity with Saccharothrix xinjiangensis NBRC 101911(T) (99.3 %) and Saccharothrix texasensis NRRL B-16134(T) (98.9 %). However, DNA-DNA hybridization studies showed only 16.2 % relatedness with S. xinjiangensis DSM 44896(T) and 33.9 % relatedness with S. texasensis DSM 44231(T). Based upon genotypic and phenotypic differences from other members of the genus, a novel species, Saccharothrix saharensis sp. nov., is proposed, with SA152(T) ( = DSM 45456(T) = CCUG 60213(T)) as the type strain.

New dithiolopyrrolone antibiotics induced by adding sorbic acid to the culture medium of Saccharothrix algeriensis NRRL B-24137.

Dithiolopyrrolone antibiotics, produced by several microorganisms, are known for their strong antimicrobial activities. This class of antibiotics generated new interest after the discovery of their anticancer and antitumor properties. In this study, four new antibiotics were purified from the fermentation broth of Saccharothrix algeriensis NRRL B-24137 and characterized as dithiolopyrrolone derivatives. These new dithiolopyrrolone antibiotics were induced by adding sorbic acid, as precursor, at a concentration of 5 mM to the semi-synthetic medium. The analysis of the induced antibiotics was carried out by HPLC. The maximal production of the antibiotics PR2, PR8, PR9 and PR10 was 0.08±0.04, 0.21±0.04, 0.13±0.03 and 0.09±0.00 mg L(-1) , respectively, obtained after 8 days of fermentation. The chemical structures of these antibiotics were determined by (1) H- and (13) C-nuclear magnetic resonance, mass and UV-visible data. The four new dithiolopyrrolone antibiotics - PR2, PR8, PR9 and PR10 - were characterized, respectively, as crotonyl-pyrrothine, sorbyl-pyrrothine, 2-hexonyl-pyrrothine and 2-methyl-3-pentenyl-pyrrothine. The minimum inhibitory concentrations of the new induced antibiotics were determined.

Saccharothrix tamanrassetensis sp. nov., an actinomycete isolated from Saharan soil.

Actinomycete strain SA198(T), isolated from a Saharan soil sample of Algeria, was characterized taxonomically by using a polyphasic approach. Chemotaxonomic and morphological characteristics observed suggested that it was a member of the genus Saccharothrix . The 16S rRNA gene sequence analysis confirmed that strain SA198(T) was a member of the genus Saccharothrix and showed a similarity level ranging between 97.5 and 98.9% within species of the genus Saccharothrix , Saccharothrix australiensis being the most closely related. However, DNA-DNA hybridization values between strain SA198(T) and its closest phylogenetic neighbours, the type strains of S. australiensis , Saccharothrix xinjiangensis , Saccharothrix algeriensis and Saccharothrix espanaensis , were clearly below the 70% threshold. Based upon genotypic and phenotypic differences from other members of the genus, a novel species, Saccharothrix tamanrassetensis sp. nov., is proposed, with SA198(T) ( = DSM 45947(T) = CECT 8640(T)) as the type strain.

Contamination of common spices by aflatoxigenic fungi and aflatoxin B1 in Algeria

Spices are usually produced in areas where the climatic conditions are favourable to growth of toxigenic fungi and production of mycotoxins. This study assesses the occurrence of aflatoxigenic fungi and aflatoxin B1 (AFB1) in spices marketed in Algeria. A total of 44 spice samples (4 for each type of spice) composed of aniseed, black pepper, caraway, cinnamon, coriander, cumin, ginger, red pepper, saffron, sweet cumin, and sweet pepper were collected from four popular markets located in Algeria. Mycological analysis of the spice was by dilution plating while AFB1 contamination levels were determined by high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) after post-column derivatisation. The commonly isolated fungi were species of Aspergillus (56.4%), Penicillium (25.1%), Mucor (12.8%) and Eurotium (5.7%). Species belonging to Aspergillus section Flavi represented 28.9% of the total Aspergilli. The aflatoxin producing ability of isolates belonging to Aspergillus section Flavi was determined on coconut agar medium and confirmed by thin layer chromatography and HPLC-FLD. Ninety-four isolates (38.4%) of the 245 Aspergillus section Flavi examined produced aflatoxins. The most frequent chemotypes (84%) correspond to isolates able to produce both aflatoxin B and cyclopiazonic acid followed by the producers of only aflatoxin B. Twenty-three (63.9%) of the 36 spices contained AFB1 at levels ranging from 0.10 to 26.50 μg/kg. Two saffron (24.34 and 26.50 μg/kg) and two sweet cumin (14.65 and 19.07 μg/kg) samples were above the Algerian regulatory limit of 10 μg/kg. This work represents the first report about the occurrence of aflatoxigenic fungi and AFB1 in the common spices in Algeria.