الفهرس 
L-asparaginaseOnly 14 pages are availabe for public view
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Abstract
The current study describes isolation and screening of fungi from soil for L-asparaginase activity, included the selection a high potential fungi, characterization and identification of the potential fungi by combination approach and optimization of the process parameters for maximization of L-asparaginase production by the potential fungi.
Twenty-one fungal isolates from forty one isolates were isolated from different rhizosphere soils of Egypt showed positive for L-asparaginase reaction by producing pink color around the colony. Among various filamentous fungi tested by plate assay, the isolate BES1 and QW5 from the rhizosphere soil of Berket El-Sabaa (BES) and Quwaysna (QW) exhibited the highest zone of diameter (6.0 and 5.0 cm, respectively) and maximum activity (5.55 and 4.86 IU/ml, respectively) were considered as the potential strains and were used for further studies. Based on it’s morphological and microscopy characteristics as well as 18S rRNA sequence analysis, the two isolates designated as BES1 and QW5 were identified as Fusarium solani strain FRC#s1162 and Penicillium oxalicum strain No. KUC1674, respectively.
great promise for maximum production of L-asparaginase enzyme after optimization was detected such as incubation time, temperature, pH, carbon source, nitrogen source. The optimum incubation time for maximum L-asparaginase production from F. solani and P. oxalicum were 48 h (6.422 IU) and 72 h (8.56 IU), temperature near to 45°C and 25°C, pH 7.0 (7.594 and 7.820 IU), glucose (6.81 IU at 0.5%)and sucrose (6.21 IU at 0.5%). ammonium sulphate (0.5%) yeast extract (0.5%) appears to be the good inorganic and organic nitrogen source for F. solani and P. oxalicum, respectively.
For purification of L-asparaginase from F. solani and P. oxalicum, the ammonium sulphate precipitation method showed 12.08 and 25.12 mg/ml protein and 234U and 440 U activity. This clearly indicated that there is 149.6 and 151.2 fold increases in the protein purification with 103 % of recovery of protein by ammonium sulphate method.
Protein profiling by SDS-PAGE revealed the molecular weight of Fusarium solani L-asparaginase are 70 and 80 kDa respectively, while P. oxalicum gives a single band with molecular weight of approximately 94 kDa. The enzyme was optimized at alkaline pH of 9.0 Fusarium solani and it retains 100% active, while P. oxalicum at pH 8.0 .
It is observed that the enzyme was more stable at alkaline pH than at the acidic one. The enzyme was maximally stable at a pH range from 7.0 to 9.0 for the strains. The optimum temperature was found to be 45°C in case of F. solani and at 37°C in case of P. oxalicum and was maximally stable at 50°C to 60°C for 60 min for both strains.