螺旋藻培养液中抑制物的鉴别和去除
文献类型：学位论文
| 作者 | 王利蒙 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012-05-28 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 丛威 |
| 关键词 | 螺旋藻 自身生长抑制物 水循环 大孔吸附树脂 |
| 其他题名 | Identification and Removal of Growth Inhibitor in Culture Medium of Spirulina platensis |
| 学位专业 | 化学工程 |
| 中文摘要 | 螺旋藻含有高含量的优质蛋白和多种生物活性物质，在食品、饲料和化妆品等多个行业有重要应用潜力，是迄今实现大规模工业化生产的主要微藻之一。但是螺旋藻生产过程中存在水资源浪费严重的问题，每吨藻约耗水1000~2000吨。螺旋藻生长过程中分泌的自身生长抑制物是造成藻液难以循环使用的主要原因。本文从除去抑制物出发，筛选出了合适的吸附剂，在此基础上确定了自身生长抑制物的成分，考察了吸附剂使用的工艺参数。要点如下：通过比较螺旋藻在各种吸附剂吸附处理的藻液中的生长曲线和比生长速率，确定了大孔吸附树脂S-8和NKA-Ⅱ能吸附除去藻液中的生长抑制物，将螺旋藻的比生长速率分别提高到未处理前的1.394倍和1.305倍，和螺旋藻在新鲜培养基中的生长速度接近。选择S-8作为后续实验材料。 提取胞外多糖和有机酸，分别加入到经S-8吸附处理的藻液中，比较螺旋藻在其中的生长曲线和比生长速率，结果发现，胞外多糖的加入可恢复藻液对螺旋藻生长的抑制作用，有机酸却没有这种效果。由此确定了胞外多糖为螺旋藻自身生长抑制物成分。 通过S-8对藻液中多糖的静态吸附实验，考察了温度和pH对多糖吸附率的影响，结果发现，大孔吸附树脂S-8对多糖的吸附能力随温度上升而下降，高于30℃时，温度每升高10℃，吸附量约下降50%；当藻液pH为3.00时，大孔树脂S-8对多糖的吸附量最大。通过静态解吸实验，确定6% NaCl溶液为洗脱剂。研究了吸附动力学实验，并使用Kannan & Sundaram粒内扩散模型和Boyd液膜扩散模型对数据进行分析，结果表明，S-8吸附藻液中多糖达到吸附平衡只需30 min，Boyd液膜扩散模型对动力学数据拟合较好，-ln(1-F)~t 线性相关性可达0.9374，这说明，吸附过程中的控制步骤为多糖在液固界面上的扩散。通过假一级模型和假二级模型对吸附动力学数据进行分析，得出，假二级模型能更好地解释吸附过程，其中(t/Qt)~t线性相关度达0.9991，使用假二级模型计算出的平衡吸附量与实际值非常接近，相对误差仅为4.49%。使用Langmuir等温吸附模型和Freundlich等温吸附模型对20℃等温吸附数据进行拟合，结果得出了没有意义的速率常数和饱和吸附量。说明S-8对多糖的吸附应该是多层吸附。 通过动态吸附实验考察了上样流速对吸附曲线、冲洗曲线和洗脱曲线的影响，得出，当流速在1 SV~4 SV之间时，流速变化对三种曲线的影响不大，选取4 SV作为上样速度较为合理，此时，批次处理藻液量约为14 BV，冲洗时需要去离子水约1 BV，洗脱时需要6% NaCl溶液4.23 BV。 |
| 英文摘要 | Spirulina platensis, one of the main kinds of microalgae which have to date realized mass cultivation, contains high content of high quality proteins and bioactive substances, and has important application potentials in food, feedstock, cosmetics industries etc. However, a big problem exists in Spirulina production process is the large consumption of water resources, i.e. about 1000~2000 ton water for 1 ton Spirulina production. The main reason for culture medium’s difficulty to be reutilized is the excretion of auto-growth inhibitors during S. platensis's growing process. Aiming to remove inhibitors from used culture medium, this study screened proper adsorbents, hereby determined the components of the auto-growth inhibitors, and test the process parameters of the adsorbent. The main points were as follows. Macroporous adsorption resins S-8 and NKA-Ⅱ, which showed highest capacity for removing auto-growth inhibitors from culture medium, were screened via comparing the growth curves and specific growth rates of S. platensis in culture medium treated by different adsorbents. The specific growth rates in medium treated by S-8 and NKA-Ⅱ, were 1.394 and 1.305 folds of the untreated one respectively, which were closed to that in fresh culture medium. S-8 was thus selected as later experiment material. Extracellular polysaccharide and organic acids were extracted and added separately into the treated culture medium by S-8, growth curves and specific growth rates of S. platensis in the two groups were compared, showing that the adding of extracellular polysaccharide into the treated culture medium could recover the inhibition effect to the untreated level, while organic acids did not have this effect. Judging from this, the extracellular polysasccharide was recognized as the auto-growth inhibitor of S. platensis. This work further investigated the adsorption rates as affected by temperature and pH value via static adsorption experiment of polysaccharide in treated culture medium. Results showed that the adsorptive capacity of macroporous adsorption resin S-8 to polysaccharide decreased with increased temperature, i.e. decreasing 50% as temperature increased by 10℃ (when temperature being higher than 30℃), and the adsorptive capacity was highest when pH was at 3.00. Through static desorption experiment, 6% NaCl solution was selected as the elution. The static adsorption dynamics were investigated and analyzed with Kannan & Sundaram intraparticle diffusion model and Boyd film diffusion model, showing a period of 30 min was sufficient for polysaccharide adsorption equilibrium by S-8, and data fitted well with Boyd model (linear correlation coefficient being 0.9374), thus indicating the diffusion of polysaccharide on the solid-liquid interface was the controlling step. Analyzing the kinetic data with pseudo-first-order and pseudo-second-order model showed that the latter one could better explain the adsorption process (linear correlation coefficient being 0.9991), and the calculated equilibrium adsorption amount is close to the experimental value (error being 4.49%). Fitting the thermal-stat adsorption data at 20℃ with Langmuir isothermal adsorption model and Freundlich isothermal adsorption model gave meaningless rate constants and adsorption saturation capacity, indicating the polysaccharide adsorption by S-8 might be multilayer adsorption. The influence of sample flow rate on adsorption, washing and desorption curve was further investigated via dynamic adsorption experiment, showing that the flow rate had little effects on the three curves when it was between 1~4 SV. While a flow rate of 4 SV was selected, the culture medium amount of about 14 BV could be treated in a single batch, and 1 BV deionized water and 4.23 BV 6% NaCl solution was simultaneously needed in washing and desorption process respectively. |
| 语种 | 中文 |
| 公开日期 | 2013-09-25 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1818]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 王利蒙. 螺旋藻培养液中抑制物的鉴别和去除[D]. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：过程工程研究所
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