Growth dynamics of cyclomaltodextrin glucanotransferase producing Bacillus circulans var. alkalophilus

Abstract

The time course of the growth of cyclomaltodextrin glucanotransferase (EC 2.4.1.19; CGTase) producing Bacillus circulans var. alkalophilus (ATCC 21783) was studied using shaking-flask cultivations. The growth curve was diauxic and during the initial phase the pH decreased sharply by 1.3–1.5 units. Most of the total carbohydrates disappeared prior to the bulk growth, which corresponded to a transient peak of amylolytic enzyme activity and of reducing sugars followed by acid production. During active cell growth the pH recovered by about 0.5 units and 65% of the final CGTase appeared in the medium. Another 20% was produced during the stationary phase and 15% was produced in the death phase. The growth dynamics of two randomly selected alkalophilic Bacillus strains (ATCC 27647 and 27557) were compared with those of ATCC-strain 21783. The reference strains showed related growth behavior with the exception that the timing and magnitudes of the changes in the growth parameters measured were different. The effects of carbon source (starch), nitrogen source (yeast extract plus Bacto-pantone), sodium carbonate, and temperature were studied from the point of view of CGTase production. Key words: cyclomaltodextrin glucanotransferase; alkalophilic bacilli; cyclodextrins.