وجود و إنتشار بكتيريا الأزوتوباكتر في ترب داعمة لأشجار الصنوبر الحلبي في الجبل الأخضر- ليبيا

Abstract

The objective of this study was to determine the presence of Azotobacter bacteria in the soil supporting the pine trees under the conditions of the green mountain climate and to determine the growth number of Azotobacter bacteria and the extent of their spread in the organic and mineral part of the soil supporting the growing Aleppo pine in the Green Mountain and to know what kind of Azotobacter existing In the study area, and study the effect of some Fasters Such as salts, pH, temperature and source of carbon on the growth of Azotobacter bacteria. In order to arrive at this, samples were collected from the study's loggers. The samples collected the organic part of the Humus Layer and were separated by the degree of decomposition into two stages (early and late). Below it, samples of the mineral part were collected at depths of 0-2.5 cm, 2.5-5 cm, 5-10 cm, and samples of Rhizosphere soil were also collected, and some physical, chemical and microbiological characteristics of these samples were estimated. The bacteria were isolated and planned to obtain the bacteria in a pure Ashby farm and then examined using the microscope after dyeing the gram to identify its morphological characteristics. It was found to be Gramnegative bacteria, and the result of the microscopy was that it was a bacterium collected in pairs , As well as moving bacteria, and they grow in the environment Mannitol or Starch as a source of carbon and these specifications are important in the process of classification of bacteria targeted in this study and turned out to be Azotobacter chroococcum bacteria. As for the number of Azotobacter bacteria was most possible in the study areas in the metal part (the soil) in all its depths, followed by the area of the rhizosphere, and the organic (stages of decomposition) of the pine, and the reverse in the area of the Raziosphere for the total number of bacteria, On the organic part and then the mineral part of the soil at all depths. When we studied the pH effect test and the temperature effect test, we found that the best growth of this bacterial strain was at pH = 8 and at 30°C after 1 week of incubation and this is the condition under which the strain was adapted under the study area.The effect of salts, including sodium chloride, calcium chloride, magnesium chloride, and salt mixture on the growth of isolated Azotobacter bacteria is observed. The higher the concentration of salts, the greater the electrical conductivity and the large number of isolated Azotobacter bacteria from the study area.