Each analysis was carried out in triplicate. After agitating for 30 min, the suspension was allowed to settle for 15 min and centrifuged (3000 rpm/10min). For the measurement of the EC, 5g of the soil were mixed with 25ml of distilled water. After agitating for 15 minutes, the suspension was allowed to settle for 2 h. For samples preparation for pH determination, 10g of soil sample were mixed with 50ml of distilled water. Soil chemical analysis: we were interested in determining the electrical conductivity (EC) and pH of soil samples. Sampling: from each site, 5 soil samples were collected aseptically in sterile plastic bags from the 10cm upper layer of soil at five random locations and transported to the laboratory. In this study we were interested in isolating actinomycetes from two Moroccan saline soils and screening of isolates for the production of antimicrobial substances in three culture media of different compositions (Casein Starch Agar (CSA), Bennett's agar, Mueller-Hinton (MH) agar) and at two incubation temperatures (30РІВРЉ and 37РІВРЉ).Р”В«asins evaporation of saline water, (A) site number 1 and (B) site number 2 Therefore, it's absolutely necessary to find antagonistic microorganisms that are used as a means of bio-control. Nowadays, the control of pathogenic microorganisms by synthetic products is becoming less attracting due to the emergence of resistant strains and because of the undesirable effects of these products on the environment. However, only 100 of these antibiotics have been developed to clinical applications. Currently, over 5000 antibiotics have been screened from Gram positive, Gram negative bacteria as well as fungi. Indeed, most of the antimicrobials used today in remedying diseases caused by pathogens have been developed from actinomycetes. Most of their bioactive molecules have been shown to have antibacterial (streptomycin, tetracycline and chloramphenicol), antifungal (nystatin), antiviral (tunicamycin) and antiparasitic (avermectin) properties. They are well known as a source of antibiotics and bioactive molecules. Actinomycetes are known as the most biotechnologically valuable prokaryotic microorganisms. As with other microbial discovery research, when working with environmental samples harboring communities of novel microbial populations, the media and growth conditions chosen will enrich for certain populations and not others. Furthermore, choosing appropriate media and growth conditions is important and published media are typically associated with a particular microbial genus or species. In the conventional isolation techniques, several factors must be considered, namely, the choice of screening source, the selective medium, culture conditions and the recognition of candidate colonies in the primary isolation. The cultivation of actinomycetes from extreme environments including saline habitats is very difficult than common environments, because of their slow growth rate. Among the various extremophiles, halophilic microorganisms have developed several strategies to survive and to function in hypersaline ecosystems, such as salterns, salt mines and other hypersaline environments. Microorganisms found in extreme environments have attracted a great deal of attention, due to the production by such microorganisms of various natural compounds and their specialized mechanisms for adaption to extreme environments. Actinomycetes are widespread in nature and may occur in extreme environments.

They constitute a significant portion of the telluric microflora (10 +410 +6 CFU/ml) and (10 +7W22 10 +8 CFU/ml). They are widely distributed in nature, particularly in soil. While others inhibit the growth of only one microorganism tested which reflects a possible specificity of antimicrobial substances.Р”Р„ctinomycetes are Gram-positive filamentous bacteria with fungal morphology.

Additionally, some isolates of actinomycetes inhibit the growth of several microorganisms at once. On the other hand, some isolates, they express their antimicrobial effect on the three media at the same time. Some actinomycetes isolates show antimicrobial effect on only one culture medium, which shows a special nutritional requirement to express their antimicrobial effect. Incubation temperature of 30РІВРЉ resulted in a high number of actinomycetes (18/22) isolates with antimicrobial effect relative to the temperature of 37РІВРЉ (4/22). The abundance of bacteria isolated on CSA medium from both sites showed correlation with the physical-chemical properties of the sampling soils. Also, with regards to salinity, the second site showed to contain high salt concentration compared the first site.

Physical and chemical analysis of soil samples showed that both sites are alkaline.

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