毕业论文移动版

摘  要：木质纤维素是自然界中最丰富的可再生能源，纤维素酶可将纤维素水解为可发酵的还原糖，进而转化为生物乙醇等产品，相关领域已成为研究热点。瑞氏木霉是纤维素酶的主要产生菌株，在其生长阶段会遭遇溶氧限制问题，阻碍了纤维素酶发酵酶活的进一步提高。本研究通过外源添加氧载体的方式，以期提高瑞氏木霉T.reesei HA-1发酵纤维素酶的溶氧水平,从而改善菌体生长情况，提高发酵纤维素酶酶活。通过摇瓶发酵实验，从油酸、豆油、正十六烷、正十二烷、正庚烷五种氧载体中，筛选得到效果最为显著的正十六烷。将正十六烷应用于5L发酵罐中，罐内最低溶氧水平上升至8.0%饱和度，滤纸酶活最大值由1.20 U/ml上升到1.38U/ml，增幅为15.0%，菌体干重最大值上升18.5%。说明添加正十六烷氧载体对T.reesei HA-1发酵纤维素酶酶活和菌体生长均有显著促进作用。 66477

毕业论文关键词：纤维素酶，溶氧水平，氧载体，正十六烷

Abstract：Lignocellulose is the most abundant renewable resource naturally, cellulase can hydrolyze cellulose into fermentable  reducing sugars, thereby translating into bioethanol etc., the related fields have become a research hotspot. Trichoderma reesei is the main cellulase producing strain, it goes through dissolved oxygen limitation problem in the rapid growth stage, which inhibits the further increasements of cellulase activity by fermentation. In this study, we expected to increase the dissolved oxygen level of cellulase fermentation by Trichoderma reesei HA-1, thereby enhancing cell growth and cellulase activity by fermentation. With the shake-flask fermentation, n-hexadecane was selected as the best oxygen vector from oleic acid, soybean oil, n-hexadecane, n-dodecane and n-heptane. When n-hexadecane was added to the 5L fermentor, the lowest oxygen level was elevated to 8.0% saturation, the highest filter paper activity was increased 15.0% from 1.20 U/ml to 1.38 U/ml, and the highest dry cell weight was increased 18.5%,indicating that n-hexadecane could enhance both fermentable cellulase activity and cell growth.

Keywords: cellulase, dissolved oxygen level, oxygen vector, n-dodecane

目  录

第一章.前言 5

1 木质纤维素原料概况 5

1.1 木质纤维素原料的主要组成 5

1.2 纤维素酶概况 5

1.3 氧载体概况及在好氧发酵中的应用 7

第二章．材料与方法 8

2.1 菌种 8

2.2 实验材料及仪器 8

2.2.1 实验材料 8

2.2.2 仪器 8

2.3 培养基的配置 9

2.3.1 PDA培养基 9

2.3.2 种子培养基 9

2.3.3发酵培养基 9

2.4 发酵实验操作 10

2.4.1 种子培养 10

2.4.2 摇瓶发酵 10

2.4.3 发酵罐发酵 10

2.5 分析方法 10

2.5.1 pH测定 10

2.5.2 酶活测定 10

2.5.3 蛋白含量测定 11

2.5.4 菌体干重的测定 11 (责任编辑：qin)