论文总字数：16574字

摘 要

高密度发酵作为一个专业术语出现，已经有25年左右的历史了。酵母的高密度通常指细胞浓度达到100g/L以上。

本文选择实验室小型发酵罐作为发酵环境，酿酒酵母作为发酵对象，运用分批发酵的工艺对酵母的高密度发酵方法进行优化。接种到斜面培养基做菌种活化，划线筛选出单菌落接种到种子液培养，使用YPD培养基，摇床培养200 r/min,30 ℃, 培养时间14~18 h,接种到二级种子液以相同条件培养，接种量为10%。

在5L机械搅拌式发酵罐中对酿酒酵母发酵中的恒速流加、间歇流加、溶氧反馈流加等不同的流加方法通过酵母生长曲线进行对比。之后将工艺运用到50L自吸式发酵罐中，在现有工艺的基础上改进营养源流加工艺，采用称重补料的方式对酵母培养中流加的碳源、氮源及磷源通过酵母生成量精确补料，有效提高酿酒酵母培养中的最大菌体浓度，并通过多次重复对该工艺进行了稳定性探究。同时，进行不同酒精度水平下的实验，对比酵母生长曲线，确定最适酒精度。

关键词：高密度培养 溶氧反馈 称重补料流加 稳定性探究 最适酒精度

Study on High - density Fermentation Process of Saccharomyces cerevisiae

Abstract

The emergence of high-density fermentation as a technical term has been around for about 25 years. The high density of yeast usually refers to the concentration of cells above 100g/L.

In this paper, the fermentation medium was used as the fermentation environment, the yeast fermentation medium was used as the fermentation object, and the high density culture method of yeast was studied by batch fermentation. The cells were inoculated into the slant culture medium, and the single-colony was inoculated into seed liquid. The culture medium was incubated at 200r / min, 30 ℃ and 14 ~ 18 h. The seed was inoculated with the same culture conditions, inoculation amount of 10%

In the 5L mechanically stirred fermenter, the constant flow rate, intermittent flow and dissolved oxygen feedback flow in the fermentation of baker's yeast were compared by yeast growth curve. After the process is applied to the 50L gas-reducing fermenter, the nutrient source addition process is improved on the basis of the existing process, and the nitrogen source, carbon source and phosphorus source in the yeast culture were generated by yeast. The results showed that the maximum bacterial concentration in the yeast culture was improved, and the stability experiment was carried out by repeated experiments. At the same time, experiments under different alcohol levels were conducted to compare the yeast growth curve and to determine the optimum wine accuracy.

Key Words: High density culture; Dissolved oxygen feedback; Weighing the feed stream; Flow stability study; Best alcohol

目 录

摘要 I

Abstract i

第一章 文献综述 1

1.1酵母概述 1

1.1.1 酵母的概念 1

1.1.2 酵母的分类及应用 1

1.2酿酒酵母高密度发酵 2

1.2.1高密度发酵概念 2

1.2.2酿酒酵母高密度发酵工艺 2

1.3研究方法和主要内容 3

第二章 5L机械搅拌式发酵罐碳源流加工艺对比 4

2.1引言 4

2.2 材料和方法 4

2.2.1 实验菌种 4

2.2.2 实验仪器与试剂 4

2.2.3 实验主要培养基和溶液配制 5

2.3 实验与分析方法 5

2.3.1菌种活化及发酵种子液制备 5

2.3.2 5L机械搅拌罐流加碳源 5

2.3.3 DNS法测定葡萄糖 6

2.3.4酿酒酵母湿重的测定 6

2.3.5酒精度的测定 6

2.3.6 酵母发酵力测定 6

2.4 结果与讨论 7

第三章 50L自吸式发酵罐高密度发酵工艺 9

3.1 引言 9

3.2 材料与方法 9

3.2.1实验菌种 9

3.2.2 实验仪器与试剂 9

3.2.3 实验主要培养基和溶液配制 10

3.3 实验与分析方法 10

3.3.1菌种活化 10

3.3.2 酿酒酵母称重补料工艺 10

3.3.3 DNS法测定葡萄糖 11

3.3.4面包酵母湿重的测定 11

3.3.5酒精度的测定 11

3.3.6 酵母发酵力测定 11

3.4 结果与讨论 11

3.4.1 50L自吸式发酵罐工艺验证 11

3.4.2 50L自吸式发酵罐称量补料高密度发酵工艺研究 12

3.4.3 高密度发酵工艺稳定性试验 14

3.4.4 不同酒精度水平对酿酒酵母高密度发酵的影响 15

第四章 结论与展望 17

4.1 主要结论 17

4.2 展望 18

参考文献 19

致谢 22

第一章 文献综述

1.1酵母概述

1.1.1 酵母的概念

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