Revista de Microbiologia
Print version ISSN 0001-3714
FERREYRA, Rosana; LORDA, Graciela and BALATTI, Antonio. Production of a-amylase in acid cheese whey culture media with automatic pH control. Rev. Microbiol. [online]. 1998, vol.29, n.4, pp. 259-264. ISSN 0001-3714. http://dx.doi.org/10.1590/S0001-37141998000400005.
The influence of aeration and automatic pH control on the production of a-amylase by a strain of Bacillus subtilis NRRL 3411 from acid cheese whey was studied. Tests were carried out in a rotary shaker and in mechanically stirred fermenters. a-amylase was analysed according to DUNs method. Oxygen absorption rate was determined by Coopers method. Cell oxygen demand was determined as oxygen consumption in a Warburg respirometer. The level of dissolved oxygen was measured by means of a galvanic silver-lead electrode. Results suggest the possibility of industrial use of acid cheese whey as a carbon source for a-amylase production, since the yield was similar to that produced with lactose. The highest a-amylase levels 10,000 DUN/ml units were not attained at higher aeration rates -431 mLO2/L.h-. The indicated value correspond to a 96 h process with automatic pH control at 7.5. These conditions resulted in double concentration of a-amylase. The enzyme production was directly related to growth in the form of cell aggregates.
Keywords : Bacillus subtilis; a-amylase; acid cheese whey; automatic pH control.