http://depot.umc.edu.dz/handle/123456789/5049 2026-05-02T01:28:13Z 2026-05-02T01:28:13Z Talhi, Imen Dehimat, Laid http://depot.umc.edu.dz/handle/123456789/14734 2025-12-15T14:31:27Z 2023-03-18T00:00:00Z

Production de protéases thermostables par des moisissures thermophiles isolées à partir de sources thermales terrestres de l’Est algérien. Talhi, Imen; Dehimat, Laid The exploitation of the different samples collected from terrestrial thermal springs distributed between the wilayas of Guelma, Khenchela and Mila made it possible to obtain 53 thermophilic fungal isolates. A screening on agar medium based on skimmed milk showed that 23 isolates have a proteolytic activity, of which four (1, 6, 34 and 37) among them are considered as potential producers of proteases, were retained. The isolate 37 was selected for the rest of the work due to the thermostability of its proteases. Molecular characterization by PCR, using the ITS1/ITS4 primer, has shown that isolate 37 has a 99% similarity with Mycothermus thermophilus. The sequence of the amplification product has been deposited in the Gen-Bank database (NCBI) under accession number MK770356. The production of proteases in solid culture was much higher than in both liquid and submerged cultures. Various agro-food wastes were initially explored for the production of thermostable proteases at a lower cost, including wheat bran which proved to be the best substrate for better enzyme production. In addition, a statistical approach consisting of two designs was used to determine the optimal culture conditions allowing the greatest production of these enzymes. The use of the Plackett-Burman plan made it possible to screen the variables; temperature, spore concentration and humidity which have the most significant effect on protease production. Box-Behnken analysis showed a 6.17-fold improvement in protease production (1187.03 U/mL). This improvement was observed under the optimum conditions of 47% moisture content, 5 × 105 spores/g inoculum concentration and temperature of 42°C. The zymography technique demonstrated that the selected strain produced four proteases. These proteases are very active over a wide pH range of 8.0 to 12.0 with an optimum of activity at pH 9.0, at an optimum temperature of 60°C and they retained more than 60% of their activity at the same temperature after heat treatment for 90 min. Likewise, these thermostable alkaline proteases showed great stability towards nonionic surfactants and oxidizing agents, after a pre-incubation of 1 h at 40°C, and extreme stability towards surfactants anionic. The extracted enzymes showed excellent stability and compatibility with some commercial laundry detergents. The results of the washing performance analysis revealed considerable removal of stains from human blood and egg yolk by the enzyme extract. The eco-friendly raw protease hair removal treatment of cow and goat skin has shown very high levels of hair removal. The protein hydrolysates as well as the chitosan resulting from the valorization of shrimp waste by the proteases of the studied strain, showed an important biological activity. Finally, the purification report shows that the protease was purified with a yield of 1.73%, a purification factor of 1.027 and a specific activity of 3124.53 U/mg. Characterization of the partially purified enzyme reveals a pH of 9 and an optimum temperature of 60°C.

2023-03-18T00:00:00Z Maiza, Asma Mizou, Safia Moussa Embarek, Ilhem http://depot.umc.edu.dz/handle/123456789/14112 2023-03-19T08:14:46Z 2022-06-22T00:00:00Z

Les Infections nosocomiales à klebsiella pneumoniae multirésistante et persistante. Maiza, Asma; Mizou, Safia; Moussa Embarek, Ilhem Klebsiella pneumoniae is a multiresistant and persistent bacterium, responsible for multiple nosocomial infections, a panoply of transferable genetic elements such as integration and conjugation elements, conjugative plasmids, transposons, integrals, which offer this germ new virulence and antibiotic resistance traits, such as “BLSE” and “Carbapenemas” enzymes encoded by acquired chromosomal and plasmid genes responsible for the degradation of β- lactams and carbapenems. Antibiotic resistance is also ensured by point mutations or by acquired genes coding for changing the affinity of the antibiotic for its target or for efflux pumps that reject it, new resistance genes have recently been acquired in this bacterium (blaOXA-48, blaNDM-1) and the emergence of a new carbapenem-resistant strain in Europe called ‘ST23’. The persistence is ensured in Klebsiella pneumoniae by a mechanism called “metabolic dormancy” which is summarized in a reversible metabolic slowdown which itself is done by various mechanisms : Toxin-antitoxin type II, ppGpp, the SOS system, Stopping multiplication and all cellular activity and inhibiting the effect of antibiotics that target different cellular processes such as translation, replication, transcription. Klebsiella pneumoniae also opts for a filamentous form which allows it to grow horizontally while preventing the scissiparity in order to conserve the energy provided during the division and be able to perpetuate. These three adaptive phenomena: resistance, persistence and morphological plasticity have made antibiotic therapy ineffective against this germ ; as a result new treatment techniques have recently been innovated in order to cure Klebsiella pneumoniae infections

2022-06-22T00:00:00Z Boufercha, Oumeima Boudemagh, Allaoueddine http://depot.umc.edu.dz/handle/123456789/13435 2022-12-14T14:23:10Z 2022-07-13T00:00:00Z

Capacité des actinobactéries isolées à partir des stations d’épuration des eaux usées ainsi que Labrys portucalensis F11 à dégrader certains pesticides. Boufercha, Oumeima; Boudemagh, Allaoueddine In this study, physico-chemical analysis was conducted to evaluate the functionality and quality of effluent from the wastewater treatment plant (WWTP) of Ibn Ziad, Oued El Athmania and Sidi Merouane. The physico-chemical results revealed that the effluents of wastewater at the outlet of the three WWTPs were loading with lower organic matter than the inlet. From the samples of raw, treated wastewater and from the aeration basins of these WWTPs, 15 strains of actinobacteria were isolated and purified. On the basis of morphological, physiological and biochemical characteristics, combined with phylogenetic analysis of the 16S RNAr gene; 13 isolates were affiliated to the genus Streptomyces sp., one to the genus Actinomadura sp. and another isolate to Micrococcus sp. Preliminary screening of these strains on minimum agar media separately supplemented with 17 different pesticides resulted in the selection of 13 strains capable of degrading 9 different pesticides as the sole carbon source. Secondary screening on minimum liquid medium allowed us to evaluate the degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam by the selected actinobacteria strains. Streptomyces sp. ML and OV were considered as the most efficient strains for the degradation of these two pesticides. In this work we also studied the biodegradation of thiamethoxam by the bacterial strain Labrys portucalensis F11. The results show that this strain can degrade 41%, 35% and 100% of thiamethoxam (10,84 mg/L) as sole source of carbon-nitrogen, carbon-sulfur and carbon, respectively after 30 days of incubation. Periodic feeding with sodium acetate resulted in faster degradation of thiamethoxam. Detection and identification of biodegradation intermediates were performed by UPLCQTOF/MS/MS and the chemical structure of 12 metabolites was proposed. Degradation of thiamethoxam by strain F11 is achieved mainly by dechlorination reactions, nitrate reduction and oxadiazine ring cleavage. The impact of thiamethoxam and its degradation intermediates on the germination of Lactuca sativa, the bioluminescence of Vibrio fescheri as well as on the Toxi-Chromo assay showed that L .portucalensis F11 efficiently degrades thiamethoxam to non-toxic metabolites. The present work demonstrates that actinobacteria and L .portucalensis F11 can be used effectively for the detoxification of such sites contaminated by these pesticides.

2022-07-13T00:00:00Z Dehimat L. Bouneghou Samai Batoul Bouziane Zahira http://depot.umc.edu.dz/handle/123456789/5130 2022-05-24T09:21:41Z 2017-01-01T00:00:00Z

L’effet inhibiteur depythium sp. sur la croissance mycélienne de fusarium roseum et d’alternaria alternata Dehimat L.; Bouneghou Samai Batoul; Bouziane Zahira 36 f.

2017-01-01T00:00:00Z