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首页> 外文学位 >Optimization of citric acid production by Aspergillus niger NRRL 567 in various fermentation systems.
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Optimization of citric acid production by Aspergillus niger NRRL 567 in various fermentation systems.

机译：黑曲霉NRRL 567在各种发酵系统中柠檬酸生产的优化。

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摘要

Among the various fungal strains screened for citric acid production, Aspergillus niger is known to produce considerable amounts of citric acid and other organic acids when cultivated in carbohydrate-rich medium in solid substrate fermentation (SSF). Since A. niger on a solid substrate grows under conditions similar to the natural habitat, SSF is ideal to cultivate A. niger for the purpose of producing citric acid.; An initial optimization (study 1) was conducted in batch type fermentation experiments using peat moss supplemented with glucose to simulate an organic waste. The effects of various nutrients (glucose, (NH4)2SO 4, KH2PO4 and NaCl), fermentation parameters (moisture content, temperature, inoculum density, composition of solid substrate and particle size) and of initial level of potential stimulators (ethanol, methanol, phytate and surfactant) were evaluated with respect to citric acid production by A. niger grown on damp peat moss. In these experiments, optimization using a traditional 'one-factor-at-a-time' method was applied to determine key factor ranges for the production of citric acid. When the fermentation was carried out using the final optimal conditions. This allowed for a 50-fold increase in citric acid production compared to the production of citric acid by A. niger grown on peat moss supplemented with 100 g glucose/kg DPM.; A second set of experiments (study 2) was conducted to optimize fermentation conditions for citric acid production in a column bioreactor. A. niger NRRL 567 grown on damp peat moss was held within a column bioreactor and periodically irrigated with a glucose-rich solution simulating field conditions. Three variables including aeration, thickness of solid substrate bed and incubation temperature were optimized using a 23 full factorial design (FFD). Under optimum, the total citric acid production and yield were 120.6 g/kg DPM and 18.5% respectively.; A third experiment (study 3) compared the production of citric acid by A. niger in submerged fermentation using cheese whey, as opposed to batch and semi-continuous fermentation using peat moss. Various fermentation conditions such as nutrients (glucose, (NH4)2SO 4 and KH2PO4), stimulators (methanol, olive oil and phytate) and fermentation parameters (pH, fermentation time and inoculum density) were optimized using a central composite design (CCD). Citric acid production improved citric acid production by a factor of 13.3 when compared to the production of citric acid by A. niger NRRL 567 using whey-based medium (50 g/l) alone.; As compared to submerged and semi-continuous fermentation, Batch type SSF could take higher levels of initial glucose and produce the high concentration of citric acid within a shorter period of time. Thus, SSF may be considered to be better technique than submerged fermentation, if main disadvantage like non-homogeneous fermentation conditions could be overcome.
机译：在筛选用于柠檬酸生产的各种真菌菌株中，已知黑曲霉在固体底物发酵（SSF）的富含碳水化合物的培养基中培养时会产生大量柠檬酸和其他有机酸。由于黑曲霉在固体基质上的生长条件类似于自然栖息地，因此，SSF是种植黑曲霉以生产柠檬酸的理想之选。在分批式发酵实验中进行了初步优化（研究1），使用添加了葡萄糖的泥炭藓模拟有机废物。各种营养素（葡萄糖，（NH4）2SO 4，KH2PO4和NaCl），发酵参数（水分含量，温度，接种密度，固体底物组成和粒径）以及潜在刺激物的初始水平（乙醇，甲醇，评估了在潮湿的泥炭苔藓上生长的黑曲霉的柠檬酸生产情况。在这些实验中，使用传统的“一次一因素”方法进行了优化，以确定柠檬酸生产的关键因素范围。当使用最终的最佳条件进行发酵时。与在补充有100g葡萄糖/ kg DPM的泥炭藓上生长的黑曲霉产生的柠檬酸相比，柠檬酸的产生增加了50倍。进行第二组实验（研究2）以优化发酵条件，以在柱式生物反应器中生产柠檬酸。将生长在湿泥炭藓上的黑曲霉NRRL 567放在柱生物反应器中，并用模拟田间条件的富含葡萄糖的溶液定期灌溉。使用23全因子设计（FFD）优化了三个变量，包括曝气，固体底物床的厚度和孵育温度。在最佳条件下，柠檬酸总产量和产量分别为120.6 g / kg DPM和18.5％。第三个实验（研究3）比较了黑曲霉在使用干酪乳清的深层发酵中柠檬酸的生产，而不是使用泥炭苔进行分批和半连续发酵。使用中央复合设计（CCD）优化了各种发酵条件，例如营养物（葡萄糖，（NH4）2SO 4和KH2PO4），刺激物（甲醇，橄榄油和植酸盐）和发酵参数（pH，发酵时间和接种密度）。与仅使用基于乳清的培养基（50g / l）由黑曲霉NRRL 567生产柠檬酸相比，柠檬酸生产将柠檬酸生产提高了13.3倍。与沉浸式和半连续发酵相比，间歇式SSF可以吸收较高的初始葡萄糖水平，并在较短的时间内产生高浓度的柠檬酸。因此，如果可以克服诸如非均质发酵条件之类的主要缺点，SSF可能被认为是比深层发酵更好的技术。

著录项

  • 作者

    Kim, Jin-Woo.;

  • 作者单位

    McGill University (Canada).;

  • 授予单位 McGill University (Canada).;
  • 学科 Agriculture Food Science and Technology.; Biology Microbiology.; Chemistry Biochemistry.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 248 p.
  • 总页数 248
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农产品收获、加工及贮藏;微生物学;生物化学;
  • 关键词

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