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Chengbin Wu

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School


First Advisor

Thomas P. West


In the U.S., approximately 196 million tons of corn (Zea mays) are produced every year. A large percentage of the corn is utilized by the alcohol industry in the fermentation of starch and sugar to alcohol (Firkins et al., 1985). The residue, whole spent stillage, is separated into distillers grains and clarified stillage. The latter fraction can be dried and marketed as distillers dried solubles, or added back to distillers grains and marketed as distillers dried grain with solubles (Shroder and Heiman, 1970). For all practical purposes, distillers dried grains with solubles is the complete corn grain minus the starch and sugars, which have been removed by the fermentation process (SDSU, 1990). Distillers dried grains with solubles not only contains a high protein content but its fiber and fat content are also fairly high. It is a high energy-content material (Lee et al., 1991). Because of its characteristics, distillers dried grains with solubles has been utilized in the area of animal feeds for many years. Generally, it is not used as a complete animal feed, but instead is provided as a supplement to other feeding materials (Zhu et al., 1991). Even though the grains with solubles has a high level of protein content, it has a low content of certain amino acids which are essential to animal growth. It has been demonstrated that lysine is the most limiting amino acid in distillers dried grains with solubles, followed by threonine and methionine (Danielson et al., 1988; Newman et al., 1989). In order to elevate the concentration of the essential amino acid lysine in the grains with solubles and thereby make it a suitable animal feed, synthetic lysine must be used to supplement the distillers dried grains with solubles. Unfortunately, this supplementation increases the price of distillers dried grains with solubles. The primary objective of this project was to isolate lysine-overproducing fungal mutants and then use these mutants to increase the lysine content in corn distillers dried grains with solubles by various treatments. The overall goal was to elevate the nutritional value of corn distillers dried grains with solubles and ultimately, make it more economical animal feed.

Library of Congress Subject Headings

Distillers feeds
Lysine in animal nutrition
Corn as feed




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