Avaliação de métodos para manutenção e preservação de bactéria esporulada produtora da enzima CGTase

Abstract

The conservation of cells without morphologic, physiologic or genetic changes is a biotechnology necessity. Bacillus firmus strain 37 is a sporulating bacteria that produces the cyclodextrin glycosyltransferase (CGTase) enzyme, which transforms starch into cyclodextrins (CDs). This study aimed to evaluate the maintenance and preservation of B. firmus strain 37 stored in a solid medium, sterile soil and in glycerol at low temperature (-70oC). In order to evaluate the best bacteria maintenance method, cell immobilization procedures were used on inorganic matrices. The immobilized cells were submitted to the initial biomass effect test and scanning electron microscopy (SEM). Periodic transfer was not an appropriate method, because the strain reduced the production of CGTase. The storage in sterile soil proved effective and the enzyme production remained constant. The conservation in low temperatures was also satisfactory, with cell counts practically the same after 360 days. The immobilization evaluated by SEM did not show any difference in the adsorption of the cells preserved by the different methods. The same happened for the initial biomass effect test, which presented higher beta-CD production when 1.5 g of cells was used.