バイオレメディエーションと生分解のジャーナル

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Optimization of Medium Components for the Production of Phytase by R. Oryzae using Statistical Approaches

Richa Rani, Sidharth Arora, Sudhir Kumar and Sanjoy Ghosh 

The aim of this study was to determine the optimum levels of nutrients for the production of phytase by heat stressed Rhizopus oryzae in submerged fermentation. Plackett-Burman Design (PBD) was initially adopted for evaluating the medium components (mannitol, K₂HPO₄, Na₂HPO₄ and sodium phytate) affecting the phytase production most. The optimum levels were estimated by Central Composite Design (CCD) of Response Surface Methodology (RSM). The interactive effects of phosphorus sources were found to have significant effect on phytase yield. Application of Genetic Algorithm (GA)/Nelder-Mead Downhill Simplex (NMDS) with RSM model was proved to be more efficient approach for optimization of phytase production by Rhizopus oryzae. A 7.95-fold increase in phytase production (12640 ± 1450 Ul^-1) was achieved at the GA-predicted optimum concentration of (gl^-1); mannitol 22.8, K₂HPO₄ 5.18, Na₂HPO₄ 3.25, and sodium phytate 9.68, compared with the phytase yield before optimization (1589 ± 135 Ul^-1). In the bioreactor studies, the enzyme yields were sustainable to that of the shake flask however, the time required for maximum phytase production was significantly reduced (288 h to 96 h), resulting in an increase in productivity by 3.32-fold.