Optimization of Trace Metals Concentration on Citric Acid Production by Aspergillus niger NRRL 2001
Optimization of Trace Metals Concentration on Citric Acid Production by Aspergillus niger NRRL 2001
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DOI：
10.1007/s11947-007-0009-y
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发表时间：
2008-09-01
影响因子：
5.6
通讯作者：
Rodrigues, S.
中科院分区：
文献类型：
--
作者：
Guilherme, A. A.;Pinto, G. A. S.;Rodrigues, S.
目前，柠檬酸是通过黑曲霉深层发酵生产的。工艺产量取决于培养基的成分以及微生物菌株。在这项工作中，介绍了 Fe+3、Zn+2 和 Mn+2 对 A. niger NRRL 2001 柠檬酸生产的影响。培养基组成为葡萄糖(120g/L)、KH2PO4(1.0g/L)； K2HPO4 (1.0 g/L)、MgSO4 中心点 7H(2)O (0.5 g/L)、(NH4)(2)SO4 (3.0 g/L)。根据实验设计，离子 Fe+3、Zn+2 和 Mn+2 的浓度发生变化。实验在轨道摇床中以 200 rpm 和 30 摄氏度进行。该菌株产生的胞外多糖也进行了定量。最佳实验条件是在不存在Mn+2 的情况下使用7.0 mg/L Fe+3 和6.5 mg/L Zn+2 。使用该实验条件没有观察到草酸形成。金属含量对于多糖的生产并不重要。发酵10天后达到最高产率（2.95 g L-1 day(-1)）。此后，生产率略有下降。 20天内，柠檬酸产率（2.44 g L-1 day(-1)）为最高产率的82%。柠檬酸转化率不断提高，发酵20天，产率达45.8%。
Citric acid is nowadays produced by submerged fermentation of Aspergillus niger. The process yield depends on the composition of the medium, as well as on the microorganism strain. In this work, the effect of Fe+3, Zn+2, and Mn+2 on citric acid production by A. niger NRRL 2001 is presented. The culture medium composition was glucose (120 g/L) KH2PO4 (1.0 g/L); K2HPO4 (1.0 g/L), MgSO4 center dot 7H(2)O (0.5 g/L), (NH4)(2)SO4 (3.0 g/L). The ions Fe+3, Zn+2, and Mn+2 had their concentrations changed according to an experimental design. The experiments were carried out in an orbital shaker at 200 rpm and 30 degrees C. The strain produced an extracellular polysaccharide that was also quantified. The optimum experimental condition was found using 7.0 mg/L of Fe+3 and 6.5 mg/L of Zn+2 in absence of Mn+2. No oxalic acid formation was observed using this experimental condition. Metal contents were not significant for the production of the polysaccharide. The highest production rate (2.95 g L-1 day(-1)) was reached after 10 days of fermentation. After this period, the productivity decreased slightly. In 20 days, the citric acid production rate (2.44 g L-1 day(-1)) was 82% of the highest productivity. The conversion into citric acid increased continuously, yielding 45.8% in 20 days of fermentation.