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Wheat straw was used as a source for isolating thermophilic bacteria and as a substrate for cellulase production. Twenty five of thermophilic bacterial isolates were isolated from agricultural waste samples on Luria-Bertani (L.B) agar plates. These bacterial isolates were qualitatively tested at 50˚C for cellulose production by flooding plates containing mineral salts medium (MSM) with 2% of wheat straw and 0.5% Congo red dye for 15 min followed by repeating wash with 1M NaCl. Results showed that 12 isolates gave a clear zone, after Congo red dye staining of plates; this indicated that the colonies produce cellulase. Bacterial isolates were screened for enzyme activity in submerged liquid MSM with 2% of wheat straw at 50˚C. The produced enzyme is then examined for reducing sugar release in liquid medium. Results revealed that 2T5, 3T13 and 3T18 isolates were the highest in producing cellulase enzyme 5.9, 13.7 and 14.3 Unit/ml, respectively. The most active isolates 2T5, 3T13 and 3T18 were identified on the basis of morphological, biochemical characteristics and API identification kits, they were identified as Bacillus subtilis, Bacillus megaterium and Bacillus licheniformis, respectively.

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In this research, two activated sludgeexperimental laboratoryplants wereconstructed and operated using dairy wastewater. One of these plants were operatedat high temperatures of (40 – 60 oC) “Thermophilic microorganisms reactors",whereas the other one were operated at constant temperature of (25 oC)“Mesophilicreactor”. The resultsshowed that the organic removal efficiency of "Mesophilicreactor" was more than the "Thermophilic reactors" and it decreasedwith increasingthe temperature.The kinetic parameters for the both mode of operations were alsocalculated. The value of the substrate removal rate constant (k) for the "Mesophilic,25ºC" reactor was (0.017 day-1) and it was greater than others for the thermophilicreactors.(k) and (Y) decreased with increasing the temperature. The values of (Ks),(Umax), and (Kd) in the thermophilic reactors were more than the corresponding valuesin the mesophilic reactor and increased with increasing the temperature.

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A laboratory-scale experiment was carried out to estimate the influence of temperature fluctuation on thermophilic anaerobic digestion of municipal organic waste (MOW). Heating failure was simulated by decreasing temperature gradually from 55 °C to 20 °C gradually 2 h time need for temperature decrease and recovery. Under conditions of 8.0 g/ (L•d) and 15 d respectively for MOW load and retention time. Following results were found: (1) biogas production almost stopped and VFA (Volatile Fatty Acid) accumulated rapidly when accompanied by pH decrease. (2) With low temperature (20°C) duration of 1, 5, 12 and 24 h, the thermophilic anaerobic digestion system reproduce methane after temperature fluctuation of 3, 11, 56 and 72 h. (3) The bacteria was influenced by the temperature fluctuation where it decayed, hydrolysis, acidification was high as the low temperature interval lasted. (4) The thermophilic microorganisms were highly flexible to temperature fluctuation.

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This research aimed to detect the tolerance of a local soil thermophilic isolate to some heavy metals (HM) and determine of minimal inhibition concentration (MIC). Also, plasmid profile was studied and its relationship with HM resistant. Deleterious effect of mercury (Hg), chromium (Cr) and Cobalt (Co) were evaluated on bacterial shape, growth and DNA scan between 200-40nm. Mutation effect was also studied. Local thermophilic Bacillus stearothermophilus was resist zinc, molbidium, silver at a concentration reached 80mM; it is sensitive to Hg, Cr and Co with MIC reached 0.004, 0.03 and 0.007 respectively. Plasmid profile revealed the absence of plasmid from B. stearothermophilus. Some of bacterial shapes were changed to short bacilli, coccobacilli and cocci; many bacterial cell fragment were seen after treatment with Hg, Cr and Co. Bacterial growth decreased when treated with Hg and Cr after 18h while, little effect was seen with Co treatment with Hg and Co induced heat sensitive mutation with 200-300 mutated cfu /ml from 104 cfu/ml; no heat sensitive mutation were detected for Cr treatment. DNA UV scan 200-400nm showed no changes with Hg while, curve shape changed for Cr and cobalt.

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