利用黑麴菌固定化分生孢子進行檸檬酸生?

Abstract

利用Aspergillus aceutus TMB 2022 之分生孢子固定於calcium alginate之膠體上，進行檸檬酸醱酵。含2.32×10^8個分生孢子之懸浮液1 ml，包埋於Sodium alginate水溶液中，以製成3% Na-alginate (W/V),然後逐滴加入0.1 M CaCl2溶液中，膠體在室溫(20°-22℃)下靜置3小時，便形成3% Ca-alginate。將20 g 3% Ca-alginate之固定化分孢子培養在人工合成培養基，內含14%蔗糖，0.25% (NH4) 2S04, 15% KH2PO4，0.025% MgSO4•7H2O，另外加上0.03 mg/のCuSO4•5H2O, 0.5 mg/のZnCl2, 1.3 mg/のFeCl3•PH2O, PH 3.8。於35℃下進行表面培養，10天後可以獲得無水檸檬酸65.42 g/の，同樣條件下，在分批式培養，發現經固定後的分生孢子，可以維持較長的產酸期(31天)，無水檸綜酸產量從第2批到第4批均超過70 g/の，最高達77.02 g/の;對消耗糖收率約在65.65-69.83%之間。相反的，遊離分化孢子維持較短的產酸期，約17天，在分批式培養下，無水檸檬酸的最大收量為71.07 g/の(第2批)，但隨著批數的增加而檸檬酸量銳減。

Conidia of Aspergillus aculeatus TMB 2022 were immobilized in calcium alginate beads for use in the production of citric acid. A 1.0 ml conidia suspension containing about 2.32×10^8 conidia were entrapped into sodium alginate solution in order to prepare 3% Na-alginate(w/v), and then added drops to a 0.l M CaCl2 solution; the beads were allowed to stand at room temperature(20-22℃) for 3 hours to form 3% Ca-alginate. 20 grams of 3% Ca-alginate immobilized conidia were inoculated into synthetic medium containing 14% sucrose, 0.25% (NH4)2SO4, 0.15% KH2PO4, 0.025% MgSO4.7H2O with the addition of 0.03mg/l CuSO4.5H2O, 0.5mg/l ZnCl2, 1.3mg/l FeCl3.6H2O, pH 4.3. After fermentation at 35℃ for 10 days by surface culture, it can produce 65.42g/l anhydrous citric acid. Under the same condition at the batch-wise culture, it is found that immobilized conidia could maintain a longer period for citric acid production(31 days), over 70g/l of anhydrous citric acid at each run from No. 2 to No. 4, maximum yield for anhydrous citric acid reached 77.02g/l at run No. 2; in Contrast, free conidia maintained shorter period of acid producing phase, about 17 days, maximum yield for anhydrous citric acid was 7l.07g/l at run No. 2 but dropped down quickly as the run No. increased.