SURVIVAL OF AZOSPIRILLUM BRASILENSE UNDER DIFFERENT MOISTURE CONTENT LEVELS

The survival and proliferation of free and alginate immobilized, Azospirillum brasilense in a bulk soil collected from Derna region at different moisture content levels (10%, 40% and 60 %). A reduction of cell number in the experimental units (sterile or non-sterile soil) for all the tested moisture levels was observed after 15 days after the inoculation. Nevertheless, different parameters among the level of moisture content could be observed in the reduction of the population .soil-sterilization did not affect Azospirillum survival and proliferation, and results presented in results show that Azospirillum brasilense total content was not affected by the sterility of the soil. In general, Azospirillum brasilense strain isolated from Derna soil survived well and for long period (75day) in bluk soil (without plant roots). In this study the presence of moisture in the soil as well as the soil- type of Derna which is rich in organic matter maintained Azospirillum brasilense population of a level high enough to be detected 75 days after inoculation.