Citric acid production using immobilized conidia of Aspergillus niger TMB 2022

✍ Scribed by S. S. Tsay; K. Y. To

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 544 KB
• Volume: 29
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/bit.260290302

✦ Synopsis

Conidia of Aspergillus niger TMB 2022 were immobilized in calcium alginate for the production of citric acid. A 1-mL conidia suspension containing ca. 2.32 x IO'conidia were entrapped into sodium alginate solution in order to prepare 3% Ca-alginate (w/v) gel bead. Immobilized conidia were inoculated into productive medium containing 14% sucrose, 0.25% (NH4I2CO3, 0.25% KH2P04, and 0.025% MgS04.7Hz0 with addition of 0.06 mg/L CuS04.5H20, 0.25 mg/L ZnCI2, 1.3 mg/L FeCI3.6H20, pH 3.8, and incubated at 35°C for 13 days by surface culture to produce 61.53 g/L anhydrous citric acid. Under the same conditions with a batchwise culture, it was found that immobilized conidia could maintain a longer period for citric acid production (31 days): over 70 g/L anhydrous citric acid from runs No. 2-4, with the maximum yield for anhydrous citric acid reaching 77.02 g/L for run No. 2. In contrast, free conidia maintained a shorter acid-producing phase, ca. 17 days; the maximum yield for anhydrous citric acid was 71.07 gIL for run No. 2 but dropped quickly as the run number increased.