Plas c bags (Low Density Polyethylene (LDPE) belong to the polymers, which plays a very important role in our daily lives by their diversi ed applica on. However, the accumula on of the plas c bags in the environment cons - tutes a serious problem and a real source for visual nuisance, pollu on of soil and marine environments. Furthermore, their biodegradation was the safest method of breakdown that possibly leaves behind less toxic residues and showed poten al of bio-geo chemical cycling of the substrate. The aim of the present work was the characterization of the isolated bacterial strains from a municipal land ll area of Tlemcen, North West Algeria, which were implicated by the biodegrada on ability of the Low Density Polyethylene. The degradation of the Low Density Polyethylene was inves gated by studying the bacterial growth of the isolated, inoculated on a solid culture medium, which was composed of LDPE as the sole carbon source with and with- out a nitrogen source and the selec on was based by the determination of the produced diameter of hydrolysis clear zone on the surface. Furthermore, the isolated, selected degrading Low Density Polyethylene bacterial ML002 has been iden ed by the study of their morphological, biochemical charac- teris cs and the ampli ca on of the fragment, coding the region of ARN 16S. The use of the API system indicated their belonging to the genus Bacillus Cereus, which has reduced the weight of LDPE by 0.26, 1.28, 1.53% a er 30, 90, 120 days respec vely. Furthermore, the amplified of the fragment, coding the region of ARN 16S by the isolated, selected bacterial ML002 indicated a similarity of 99.394% with Bacillus wiedmannii and Bacillus proteolyticus and 99.293% homology with Bacillus toyonensis, Bacillus cereus and Bacillus thuringiensis.

The alarming situation of the increasing problem of the antibiotics resistance in the whole world requires an immediate need of the exploration of better alternatives for combating resistance. The main aim of the present work was the isolation and the screening of large range of lactic acid bacteria with important potential of antibacterial activity against multidrug resistance pathogenic strains and the characterization of the molecules responsible for anti-bacterial activity. The primary screening indicated the isolation of total of 200 lactic acid bacteria (LAB) from harvested milk (camel and goat) and tradi-tional fermented dairy products (Jben and kamaria) of south Algeria and in-vestigated for their antibacterial activity against clinical pathogens bacteria. Furthermore, Nineteen representative isolates (19) were selected and char-acterized with regard to their functional properties. The obtained results indicated that produced bacteriocin by both bacterial strains L. raffinolactis LAB9 and Leuconostoc mesenteroides subsp. cremoris LAB13 has manifested an excellent antagonistic activity against P.aeruginosa (PA) and Staphylococcus aureus (MRSA), which was Methicillin resistant Staphylococcus aureus (MRSA). A Further investigation indicated that the produced bacteriocin by LAB9 and LAB 13 were heat stable, where their inactivation was observed when treated with pepsin and trypsin. Additionally, the purification of the produced bacteriocin by L.raffinolactis LAB9 and Leuconostoc mesenteroides subsp. cremoris LAB13 has been achieved by the using of the partial ammonium sulfate precipitation. The technological properties and the stability of bacteriocins of LAB may lead for bioprospection of antibacterial components in the current struggle against increasing pandrug resistance and slowing down the expansion of multi drug resistance.

No abstract

Bacteria are attracting the interest of worldwide investors; their use is interesting in several industrial fields, this organism produces a wide variety of extracellular enzymes, including proteases. The objective of this study was to evaluate the production of protease by different bacterial strains isolated from local marine samples collected from the Cap Rousseau beach in the Oran city, northwestern Algeria, 44 bacterial isolates were tested for protease production by cultivating them on skim milk agar medium. The proteolytic activities of all strains were tested using skim milk agar and gelatin agar. Among the 14 isolates that showed a significant hydrolysis diameter, two bacterial strains EC23 and EC2S3 demonstrated the highest potential for protease production and they were selected for further studies. In addition, the extracellular protease was examined using the fermentation production medium at 30°C for 48h, with a constant agitation of 150 rpm. The enzyme activity was determined under varying conditions of pH, incubation temperature, and salt concentration, using Sigma's Universal Protease Activity Assay. The enzyme from EC23 strain showed higher activity in all cases than the EC2S3 strain, which indicated that it was the most ideal organism for enzyme production.

Cette présente fiche est une revue générale sur la grenade Punica granatum, en axant sur son historique, sa géolocalisation, ses symboles dans différentes cultures mondiales et les techniques d’amélioration de quelques variétés existantes.