The addition of inorganic fertilizers to treat crop soil and increase its production has become a necessity and a tool used around the world. These fertilizers contain different quantities of uranium and thorium. Therefore, tons of radionuclides from natural radioactive series 238 U, 235 U and 232 Th are dispersed in the environment due to a high use of fertilizer in agriculture. In this work, the radioactivity levels were determined in two fertilizers and in fertilized and unfertilized soil samples collected at various depths from the Algerian agricultural region of El-Athmania Mila, using high resolution gamma ray spectroscopy. The activity concentrations of 226 Ra, 232 Th and 40 K for fertilized and unfertilized soil samples were found unchanged as a function of depth and ranged from 23.72

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Thirty two strains of Aspergillus genus were isolated from soil samples obtained from particular ecosystems: Laghouat endowed with a desert climate and Teleghma with a warm and temperate climate. Based on the morphological aspect, this collection was subdivided into ten phenotypic groups. This identification was confirmed by molecular analyzes using a molecular marker of the genu ribosomal 18s. This marker will allow us to associate our sequences with those of known organisms. In order to discover new antibiotic molecules, the antibacterial activity was performed against two Gram positive bacteria: Staphylococcus aureus and Bacillus subtilis and also two Gram-negative bacteria: Escherichia coli and Pseudomonas aeroginosa, using two different techniques: Agar cylinders and disks technique. The results show that the fungal species have an activity against at least one test bacterium. The Gram positive bacteria were the most affected, where the averages of the inhibition zones reach 34.33 mm. However, Gram-negative bacteria showed less important results from 0 to 12.00 mm. It is recorded that the antibacterial activity was studied for the first time in the following two species: Aspergillus niveus and Aspergillus wentii. Furthermore, an indepth study is underway on bioguided fractionation, which would identify individual components and lead to the isolation of the active ingredient.

The production of an acid protease by liquid fermentation is performed on a medium based on decommissioned dates by a local mold isolated from an extreme environment. The used mold is isolated from the thermal soil in Hammam Safsaf of Teleghma (Algeria). Phenotypic and molecular identification has shown that it is Aspergillus niger. This fungi strain exhibited exo-protease activity on milk agar. The fermentation medium based on decommissioned dates is enriched by other factors according to a statistical method; the plan of Plackett and Burman. This method (N = 8 experiments and N-1 factors) allowed the optimization of the enzyme production and the growth of the mold. The statistical analysis of the obtained results shows an increased enzyme activity (650.20U), in the presence of yeast extract and salts with probabilities p = 0.239 for the first and p = 0.190 for the second. Furthermore, the corn-steepliquor (p = 0.229) and yeast extract (p = 0.053) present a significant effect on mold growth. In conclusion, the culture of A. niger on optimized medium gives good yields of biomass and proteolytic activity compared to the basal medium. These results are encouraging. In fact, the use of a cheap and available substrate such as decommissioned dates saves the cost price of fermentation on an industrial scale.

In recent years, bio-healing based on microbial induced carbonate precipitation in cracks has been widely exploited to improve concrete properties and thus increase its durability. In this context, the present study aims to explore the possibility of using nine bacterial isolates as biohealing agent of cementitious materials; these bacteria (coded B1 to B8) were obtained from the three different rocky sites, i.e., 795 L1 (limestone rock site), 795 L2 (ordinary soil site), and 812 (clayey site); situated in Oulad Rahmoun (Constantine-Algeria). The primary identification showed that eight isolates belonged to a Bacillus genus, and one isolate B8 developed particularly morphological characterized by branched and septate hyphae. The isolates B4 and B8 were selected for their ability to produce calcium carbonate in precipitate calcium (PC) liquid and solid media after five days of incubation. The addition of urea in PC liquid media accelerated the formation of calcite which appeared after 3 days of incubation. The growth curve of both selected isolates on LB liquid medium showed that B8 was characterized by a long exponential growth phase (up to 72 hours) compared to B4 which had an exponential phase up to 48 hours, which could explain the largest amount of calcite precipitate observed in the case of B8 cultivated in PC liquid medium. Results of the bio-healing experiment carried on cementitious batches showed that a beginning of a slight repair of the cracks from the 11th day was only observed in the case of the bacterium B8 but the bio-healing capacity was absent in the control. This bio-healing agent was identified as Micromonospora echinospora (NCBI-NO139612), according to N-Blast of 16S-DNA sequence. In conclusion, the present study is the first to isolate M. echinospora species from rocky sites; and to describe it as an efficient bacterial agent in concrete bio-healing applications.

In the interest of discovering new antibiotic molecules, the antibacterial activity of three fungal strains namely: Aspergillus quadrilineatus, Aspergillus niveus, and Aspergillus wentii isolated from particular ecosystems was sought against six bacterial strains including three with Gram-positive staining (Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis) and three with Gram-negative staining (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae). The results of the agar cylinder technique highlighted that the three fungal strains showed a considerable antibacterial activity. In order to optimize the extraction conditions of the bioactive molecules, five solvents in different polarities were tested, of which chloroform turned out to be the best one. After the selection of this solvent, four culture media of different compositions were used in order to determine the most adequate medium for the production of antibacterial substances. The results revealed that Czapek-dox medium supplemented with yeast extract turned out to be the most favorable one for the production of bioactive molecules from both strains: A. quadrilineatus and A. niveus, while the most suitable medium for the A. wentii strain was Sabouraud. In addition, a study of the antibacterial effect of organic extracts by the Biolog micro-culture system was performed using a range of concentrations. The obtained results revealed that the extracts of the three fungal strains presented a remarkable activity with different concentrations and this, against all the tested bacterial strains. It was recorded only for the three used fungal species, the antibacterial activity was studied for the first time by the Biolog system.

In the interest of searching new antibiotic substances, the antibacterial effect of Aspergillus quadrilineatus fungal strain (MH109538) has been evaluated against sensitive bacteria (S. aureus, E. faecalis, B. subtilis and E. coli) and resistant bacteria (P. aeruginosa and K. pneumonia), following the disks technique. The obtained result confirms the capacity of this strain to produce antibacterial molecules. In order to analyze and characterize these bioactive metabolites present in the crude extract, which was fractionated by column chromatography. The fractions were then separated by thin-layer chromatography. The detected spots were sampled and tested against the most sensitive bacteria (S. aureus). The results have revealed that only one fraction showed an antibacterial activity. This active fraction was analyzed by liquid chromatography coupled with mass spectrometry (LC/MS) in order to obtain the elemental composition of the present compounds. The molecular ions fragmentation (LC/ MS/MS) were used to determine the deployed formula of these compounds. The analysis of the results by Xcalibur 2.2 software reveals the presence of 24 molecules, and this, based on the retention times of the peaks obtained in the chromatogram, where, the m/z ratios, the formulas, as well as the intensities of the various compounds detected are determined.

In the interest of discovering new antibiotic molecules, the antibacterial activity of three fungal strains namely: Aspergillus quadrilineatus, Aspergillus niveus, and Aspergillus wentii isolated from particular ecosystems was sought against six bacterial strains including three with Gram-positive staining (Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis) and three with Gram-negative staining (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae). The results of the agar cylinder technique highlighted that the three fungal strains showed a considerable antibacterial activity. In order to optimize the extraction conditions of the bioactive molecules, five solvents in different polarities were tested, of which chloroform turned out to be the best one. After the selection of this solvent, four culture media of different compositions were used in order to determine the most adequate medium for the production of antibacterial substances. The results revealed that Czapek-dox medium supplemented with yeast extract turned out to be the most favorable one for the production of bioactive molecules from both strains: A. quadrilineatus and A. niveus, while the most suitable medium for the A. wentii strain was Sabouraud. In addition, a study of the antibacterial effect of organic extracts by the Biolog micro-culture system was performed using a range of concentrations. The obtained results revealed that the extracts of the three fungal strains presented a remarkable activity with different concentrations and this, against all the tested bacterial strains. It was recorded only for the three used fungal species, the antibacterial activity was studied for the first time by the Biolog system.