ISOLAMENTO DE MICRORGANISMOS ALCALOFíLICOS PRODUTORES DA ENZIMA CICLODEXTRINA GLICOSIL-TRANSFERASE (CGTASE)

摘要

A culture of an alkalophilic bacterium, rod shaped Gram positive, with high production capacity of the enzyme CGTase was isolated from soil samples of the city of Ouro Preto, Minas Gerais state (Brazil). Maximum enzyme production occurred at 37o C after 72 h of incubation, under agitation of 120 cycles per minute, in alkalophilic medium (pH 10.3) containing 2% soluble starch, 0.5 % peptone, 0.1 % K2HPO4, 0.02 % MgSO4.7H2O and 1% Na2CO3. The optimum temperature of the enzyme hydrolytic activity was between 55 and 60o C. In the absence of substrate, the CGTase showed stability of 100% until 60o C per 30 min. The addition of 10 mmol/L of calcium chloride enhanced its thermal resistance, resulting in a higher production of cyclodextrins. The optimum pH in borate buffer 50 mmol/L was 8.0. The activity and the stability in high temperatures indicate industrial potential for this CGTase. Like this, complementary studies must be realized to identify the microbial species, to purify the enzyme, to evaluate the effect of enzymatic inhibitors, to determine the type of cyclodextrins produced in greater proportion and the conversion rate of starch in cyclodextrins.