Biodegradation of some organophosphorus pesticides by soil microorganisms. The 2nd International Scientific Congress For Environment 28-30 March 2006 South Valley University, Egypt. Efficiency of some soil microorganisms in degradation of Diazinon pesticide. 12th Conference of Microbiology; Cairo, Egypt, March 18-20 2007. Interaction effect between biofertilization and organic manuring on some enzymes activity macronutrients and essential oil content of marjoram. The thirteenth Microbiology Conf., Cairo, Egypt, (2009). Response of damssisa to biofertilizers and organic manure application in presence of Pseudomonas fluorescens. The thirteenth Microbiology Conf., Cairo, Egypt, (2009). Effectiveness of organic farming on growth performance and yield of marjoram. The thirteenth Microbiology Conf., Cairo, Egypt, (2009). Effect of Biofertilization and Organic Manuring on Soil Dehydrogenase Activity, Macronutrients and Essential Oil Content of Marjoram Effect of Biofertilization and Organic Manuring on Soil Dehydrogenase Activity, Macronutrients and Essential Oil Content of Marjoram Maximization of chitosan production by Aspergillus niger on different culture conditions