19-08-2014, 11:34 AM
Substantial information exists on the effects of hydrodynamic forces on cells in defined flow geometries such as viscometers and capillaries, but little is known about shear fields in bioreactors. Cultivation of shear sensitive cells at fermenter level is very critical as the shear sensitivity of cells have an impact upon cellular morphology, biochemistry, physiology, floc size and attachment / detachment from surface, which in turn directly affects the productivity.
Substantial information exists on the effects of hydrodynamic forces on cells in defined flow geometries such as viscometers and capillaries, but little is known about shear fields in bioreactors. Cultivation of shear sensitive cells at fermenter level is very critical as the shear sensitivity of cells have an impact upon cellular morphology, biochemistry, physiology, floc size and attachment / detachment from surface, which in turn directly affects the productivity. Hence cultivation of fungal cells to estimate its shear sensitivity during metabolite production forms the mainstay of the present work.
The objectives of this project are as follows: i). Study the effect of shear sensitivity of Aspergillus niger on the production of -fructofuranosidase in shake flask level and reactor level. This includes media optimization by one-factor-at-a-time methodology followed by statistical methods for the enzyme production. ii). Study the morphological changes of Aspergillus niger during the enzyme production at various stages of fermentation. iii). Study the downstream processing of -fructofuranosidase, whichinclude ammonium sulphate precipitation and gel filtration chromatography.
Using one-factor-at-a-time methodology sucrose, yeast extract and ammonium sulfate was found to be the best carbon, organic nitrogen and inorganic nitrogen sources respectively and pH 5; Temperature 300C; 1% inoculum was found to be the best for enzyme production. Using Plackett and Burman design, a total of 11 media parameters were screened. Sucrose, yeast extract and MgSO4 7H2O were found to be the most significant factors for enzyme production. These significant factors were further screened by Response Surface Methodology (RSM); Enzyme activity was enhanced to 132.4 IU/ml. Thus, 1.9 fold increase was obtained after RSM. Effect of shear on morphology of A. niger and enzyme productivity was studied in shake flask level. Maximum activity of enzyme was showed at 180 rpm.