Three strains of Bacillus sp. (BACRP, BACNC-1 and BACAR) were isolated from soil adhered to cassava husk. CGTase specific activity for the three isolated strains was higher when cultivated at 40°C. Potato starch, cassava starch, maltodextrin and glucose were used as carbon source and growth temperatures varied from 25 to 55°C. The three isolates presented higher CGTase specific activity when cultivated with potato starch at 40°C. Isolated BACRP and BACAR presented specific activity of 4.0×10(-3) and 2.2×10(-3) U/mg prot at pH 7.0, respectively, when cultivated in mediums added with NaCl 2%; at pH 10,0 their activities were of 3.4×10(-3) and 3.0×10(-3) U/mg prot, respectively, in the same concentration of NaCl. On the other hand, the isolated BACNC-1 presented activity specific of 2.4×10(-3) U/mg prot when cultivated at pH 7.0 added of NaCl 1%, and at pH 10.0 the specific activity was of 3.4×10(-3) U/mg prot without NaCl addition. This work also showed the presence of cyclodextrins formed during fermentation process and that precipitation with acetone or lyophilization followed by dialysis was efficient at removing CDs (cyclodextrins), thus, eliminating interference in the activity assays. The enzyme produced by the BACAR strain was partially purified and β-CD was liberated as a reaction product.
Keywords: Bacillus; CGTase production; cyclodextrin glycosyltransferase.