利用玉米秸秆发酵联产丙酸和益生菌的研究
文献类型：学位论文
| 作者 | 初歆 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012-05-21 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 王云山 ; 苏志国 |
| 关键词 | 玉米秸秆 丙酸 益生菌 费氏丙酸杆菌 扩张床 |
| 其他题名 | Co-production of propionic acid and probiotics using corn stalk |
| 学位专业 | 化学工程 |
| 中文摘要 | 丙酸和费氏丙酸杆菌是理想的饲料添加剂。利用玉米秸秆发酵联产丙酸和益生菌，不仅可生产高值产品，还能促进农业废弃物利用，对资源环境的循环与利用具有重要的现实意义。本论文首先研究建立了最佳的玉米秸秆水解工艺，其次探究了费氏丙酸杆菌利用玉米秸秆水解液发酵生产丙酸的可行性，考察了玉米秸秆水解液丙酸发酵的影响因素，建立了丙酸和益生菌联产的发酵工艺，最后建立扩张床分离耦合发酵工艺，成功地解决了丙酸对发酵的抑制问题。论文的主要研究结果如下：（1）分别考察了粉碎度、纤维素酶用量、底物浓度、水解时间以及批次补料补酶对玉米秸秆水解的影响。玉米秸秆的最佳水解工艺为：底物浓度低于0.2 g/mL，纤维素酶量15 FPU/g秸秆，温度55℃，pH 4.8，水解时间48 h。研究发现，当底物浓度为0.05 g/mL时可获得葡萄糖浓度约为15 g/L的秸秆水解液，能够直接作为碳源发酵生产丙酸和益生菌。（2）研究了费氏丙酸杆菌利用玉米秸秆水解液发酵生产丙酸的可行性。结果表明，在一定玉米秸秆水解液糖浓度以下玉米秸秆水解液可以作为丙酸发酵的碳源，当初始玉米秸秆水解液糖浓度为15 g/L时最适合菌体生长和丙酸生产。此外，考察了种子液培养方式对丙酸发酵的影响，确定了“20 g/L葡萄糖种子培养基→含10 g/L纯葡萄糖和10 g/L秸秆水解液糖的种子培养基→秸秆发酵培养基”的二级种子液发酵工艺。（3）通过分析费氏丙酸杆菌发酵过程中相关参数的变化，建立了丙酸和益生菌联产的补料分批发酵工艺，有效解决了高糖秸秆水解液对丙酸发酵的抑制问题，提高了丙酸产量和菌体量。其中，补料分批工艺为：初始糖浓度为15 g/L，通过间歇补料维持葡萄糖浓度在15 g/L以下，用氨水调节pH 6.8-7.0之间，发酵周期130 h，丙酸产量可达19.97 g/L，丙酸产率和得率分别为0.15 g/L?h和0.42 g/g，活菌数达到6.90×1012 cfu/mL。（4）考察了有机酸对费氏丙酸杆菌利用玉米秸秆发酵生产丙酸的影响。结果表明，乙酸和丁二酸对发酵的影响不显著，丙酸对发酵有显著影响，当丙酸浓度高于10g/L时，丙酸产量、产率和菌体生物量下降非常显著。（5）建立了扩张床分离耦合发酵工艺，有效解除了丙酸对发酵的抑制作用，显著提高了丙酸产量。发酵192 h时，丙酸产量可达到33.37 g/L，丙酸收率为0.49 g/g，活菌数为2.42×1012 cfu/mL。与补料分批发酵相比，丙酸产量提高67%，丙酸得率提高17%。 |
| 英文摘要 | Propionic acid and Propionibacterium freudenreichii are ideal feed additives. Co-production of propionic acid and Propionibacterium freudenreichii using corn stalk can not only produce some valuable products but also promote the use of agricultural waste. In this thesis, the corn stalk hydrolysis process was first studied. Then the feasibility of propionic acid fermentation using corn stalk hydrolysate and the influencing factors of fermentation were researched. On the basis of these results, the fermentation process of co-production of propionic acid and probiotics was established. Finally the process of expanded bed separation coupled with fermentation was built which had solved the inhibition of propionic acid on fermentation. The main research results were as follows: (1) The influence of comminution degree, cellulose enzyme dosage, substrate concentration and hydrolysis time on the corn stalk hydrolysis was investigated. The optimum hydrolysis process was as follows: the substrate concentration below 0.2 g/mL, cellulose enzyme dosage 15 FPU/g, temperature 55℃, pH 4.8 and hydrolysis time 48 h. It was found that the glucose concentration of corn stalk hydrolysate was about 15 g/L when the substrate concentration was 0.05 g/mL. It could be used directly as the carbon source for propionic acid and probiotics fermentation. (2) The feasibility of production of propionic acid by Propionibacterium freudenreichii using corn stalk hydrolysate was studied. The results showed that corn stalk hydrolysate could be used as the carbon source for propionic acid fermentation when the glucose concentration of corn stalk hydrolysate was below certain value. The optimal glucose concentration of corn stalk hydrolysate medium for Propionibacterium freudenreichii fermentation was 15 g/L. Besides, the effect of seed liquid on fermentation was studied, accordingly establishing the secondary seed liquid fermentation process. The secondary seed liquid fermentation process was as follow: “20 g/L glucose seed medium →mixed seed medium which containing 10 g/L glucose and 10 g/L corn stalk hydrolysate → corn stalk hydrolysate fermentation medium”. (3) The related parameters in the process of Propionibacterium freudenreichii fermentation using corn stalk hydrolysate were analyzed. To remove the inhibition of high glucose concentration of corn stalk hydrolysate on propionic acid production, a fed-batch fermentation process of co-production of propionic acid and probiotics was established. The new process improved effectively the production of propionic acid and biomass. The fed-batch fermentation process was as follows: the initial glucose concentration 15 g/L, feeding the high glucose concentration of corn stalk hydrolysate medium to keep the glucose concentration below 15 g/L, pH 6.8-7.0 regulated by ammonia water. After fed-batch fermentation of 130 h, the production of propionic acid was 19.97 g/L with the productivity and yield about 0.15 g/L?h and 0.42 g/g, respectively.. The viable number of Propionibacterium Freudenreichii was up to 6.90×1012 cfu/mL. (4) The effects of organic acids on propionic acid fermentation were studied. The results indicated that propionic acid has an obvious effect on propionic acid fermentation, while acetic acid and succinic acid have little effect. When propionic acid concentration was higher than 10 g/L, the propionic acid production and biomass declined seriously. (5) The process of expanded bed separation coupled with fermentation was established, which solved the inhibition of propionic acid on fermentation and improved the propionic acid production. After 192 h, propionic acid production, yield and viable number of Propionibacterium Freudenreichii reached up to 33.37 g/L, 0.49 g/g and 2.42×1012 cfu/mL respectively. Compared with the fed-batch fermentation, the propionic acid production and yield were increased by 67% and 17%, respectively. |
| 语种 | 中文 |
| 公开日期 | 2013-09-25 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1856]  |
| 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 | 初歆. 利用玉米秸秆发酵联产丙酸和益生菌的研究[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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