T HIRTY five bacterial isolates of Azotobacter were isolated from different sources, nine samples from clay soil and six samples from irrigation water which collected from different localities in El-Gharebia Governorate (Basyion) and Kafr El-Sheikh Governorate (Sakha) to study their ability for accumulation of biodegradable biopolymer poly-β-hydroxybutyrate (PHB) by screening for presence / absence of PHB using a Nile-red staining approach. Also, to achieve enough biomass from the efficient isolates for the production of PHB various incubation times, different fermentation media, pH, temperature, carbon and nitrogen sources were used. Among all isolates, the amount of PHB in the three efficient isolates were Az14 (2.37 g l -1 ), Az20 (1.25 g l -1 ) from clay soil, Az6 (1.66 g l -1 ) from irrigation water. Also, it can be concluded that the optimal conditions for production of PHB from the most efficient Azotobacter sp. (Az14) were at 30 o C, pH 7, incubation time for 48 h, the best carbon source was starch at (1%) and ammonium sulphate at (0.2%) as nitrogen source. These optimal conditions lead to increase in the amount of PHB from 3.9 g l -1 to 5.31 g l -1 when using the inexpensive sources. So, these results lead to minimize the cost of production and increase the amount of PHB contribute to solving the environmental pollution problem.

TWENTY isolates of cellulase producing fungi were isolated from six samples of rotted rice straw which collected from different localities in El-Gharbia Governorate (Basyion), Kafrelsheikh Governorate (Sakha) and El-Dakahlia Governorate (El-Mansoura). On the basis of hydrolysis zone surrounding the colonies, an efficient fungus isolate (F7) for highest cellulolytic activity were chosen. According to morphological and biochemical characteristics as well as 18S rRNA sequence indicated that the isolate belonged to Aspergillus tubingensis KY615746. Effect of culture conditions for production of cellulase enzyme by A. tubingensis were investigated under Submerged Fermentation (SMF) and Solid State Fermentation (SSF) techniques. The optimum conditions for cellulase production by A. tubingensis were the best inoculum size was found to be 3%, pH 4, temperature 30 °C and incubation period 6th day where the reducing sugars attained (0.675, 0.728, 0.731 and 0.913 mg ml -1 ) with maximum activity (0.050, 0.055, 0.053 and 0.063 U ml -1 ), respectively for SMF conditions.On the other hand, the maximum cellulase activity under SSF technique with moisture level 10g : 30ml were (0.16 Ug -), incubation period 9 th day, inoculum size 4 ml:10g, pH 5 and temperature 30 °C where the reducing sugars were (1.412, 1.532, 1.551 and 1.521 mg g -1 ) with maximum activity (0.20, 0.22, 0.23 and 0.23 Ug -1 ), respectively. Based on the results, it may be concluded that rice straw waste can be a potential substrate for produce cellulase by SSF technique.