Produção de ciclomaltodextrina-glucanotrasferase com Bacillus firmus cepa 37 imobilizado em carvão de osso bovino

Abstract

The production of CGTase was performed by cells of Bacillus firmus strain 37 free in the reaction medium in a batch bioreactor and also by cells immobilized activated bovine bone char, an innovative support for this purpose, which was used in a jacketed fluidized bed column with fluid recirculation and temperature control. An experimental design was developed with three quantities of bovine bone char (3.5, 7 and 14 g ) and three aeration rates (0.5, 1 and 2 v/v/m). The use of bone char as support, aeration of the fermentation medium and the fluidized bed colunm contributed to a higher production yield of the enzyme, because the enzyme activities found were the highest compared wthi free cell. At the end of 120 h of production assays using 7 and 14 g of bone char and aeration rate equal to 2 v/v/m the CGTase activity obtained was equal to 2.5 U/mL. Furthermore, it was found that the amount of the intermediate bone char (7 g) using the maximum rate of aeration (2 v/v/m), the test was that the most significant values obtained CGTase activity, i.e., enzyme activity of 1.75 U/mL at 96 h. In contrast, for the assays using the microorganism free in the reaction medium or without aeration, the activity was found to be 0.7 U/mL after 96 h of production. Therefore, it was concluded that both aeration, the immobilization of the microorganism on bone char and the fluidized bed bioreactor were instrumental in increasing the production of CGTase. A statistical model of second order revealed that the independent variables (aeration rate and amount of bone char), the values of the enzymatic activity for the cultivation of 120 h. However , an assay using 28 g of bone char and 4 v/v/m, did not increase the activity, which remained at 2.5 U/mL, but showed a reduction in the enzyme production time that was halved to 60 h. This study has demonstrated the possibility of producing CGTase using Bacillus firmus strain 37 immobilized activated bovine bone char and showed relatively high values of CGTase enzyme activities, compared to other support matrices.