The 229 strains of black Aspergillus sp. producing citric acid were isolated from soil. Among them, the strains KTR-81 and KTR-91 were found to be superior for citric acid production. Their basic cultural conditions as well as high citric acid produci...
The 229 strains of black Aspergillus sp. producing citric acid were isolated from soil. Among them, the strains KTR-81 and KTR-91 were found to be superior for citric acid production. Their basic cultural conditions as well as high citric acid producible conditions from the liquefied sweet potato cake which is a byproduct obtained from waste material in the production of sweet potato starch, were investigated, and the results obtained are as follows:
1. Those two strains produced citric acid to maximum 63.0-63.5% from glucose when the liquefied sweet potato cake media had 16% in its total sugar concentration. The nutritional conditions added to the media were 0.15%, 0.06% and 0.03% of urea, mixture of equal amount KH_2PO_4 and K_2HPO_4, and MgSO_4·7H_2, respectively. Some hindrances were likely to be appeared in the production of critic acid by the change of the amount of the nutrients as shown above.
2. Since the oxalic acid-forming activities are relatively dull, those two strains may be available for the citric acid fermentation industry.