Research Information System
ACTA BIOTECHNOLOGICA, vol.18, no.4, pp.327-338, 1998 (SCI-Expanded)
The batch production of gluconic acid in the presence of glucose, sucrose and molasses was investigated using free mycelia of Aspergillus foetidus NRRL 337 in shake flasks. Eight growth parameters were chosen as independent variables. The temperature, pH, substrate type and initial concentrations, inoculum percentage and shake rate directly affected the specific microorganism growth and gluconic acid production rates. The optimum temperature and initial pH values were found to be 33 degrees C and five to six, respectively. The maximum specific growth and gluconic acid production rates were established as 57 g/dm(3) of glucose, 75 g/dm(3) of sucrose and 150 g/dm(3) of molasses. The optimum values of the shake rate, inoculum percentage and initial ammonium nitrate concentration were determined as 100 1/min, 0.5% and 1.5 g/dm(3), respectively. The maximum gluconic acid concentrations corresponding to these initial substrate concentrations were observed to be 8.3 g/dm(3) 17.4 g/dm(3) and 37.0 g/dm(3), respectively. The optimum specific microbial growth and gluconic acid production rates were found as 0.0145 1/h and 0.0375 g/g x h, respectively, for the fermentation conditions of S-Go= 57 g/dm(3), T = 28 degrees C, initial pH = 6.5, N = 84 1/min, A = 0.5 g/dm(3) and I= 0.5%.