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Information to Users INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, prim bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note wiD indicate the deletion. Oversize materials (e.g^ maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. A Beu & Howell information Company 300 Norm ZeeD ftoao Ann Arbor. Ml 48105-1346 USA 313/761-4700 600/521-0600 A NOVEL IMMOBILIZED CELL BIOREACTOR AND MEMBRANE ULTRAFILTRATION FOR XANTHAN GUM PRODUCTION DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Yang-Ming Lo, B.S., M.S. The Ohio State University 1995 Dissertation Committee: Approved by D.B. Min S.T. Yang Co-Advisor J.H. Litchfield Q.H. Zhang Co-Advisor Food Science and Nutrition UMI Number: 9544624 UMI Microform 9544624 Copyright 1995, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 Nbrth Zeeb Road Ann Arbor, MI 48103 To my Family ii ACKNOWLEDGEMENTS I express sincere appreciation to my co-advisors, Dr. Shang-Tian Yang, for his invaluable guidance, inspiration, insight, and encouragement throughout my research and coursework in Biochemical Engineering, and Dr. David B. Min, for his generous advice and support that lead me into fermentation technology, a combination of Food Science and Chemical Engineering. I would like to express my gratitude to the Ohio Com Growers Association and Midwest Advanced Food Manufacturing Alliance for their financial support. Thanks go to the other members of my advisory committee, Drs. John H. Litchfield and Qinghua H. Zhang, for their suggestions and comments. Gratitude is expressed to the groups of biochemical engineering and polymers in the Department of Chemical Engineering for their support and facilities. The technical assistance of Michael Kukla, Carl Scott, Don Ordaz, Kathy Wolken, and John Mitchell is gratefully acknowledged. I would like to thank Jyh-Wen Yen, Chen-Shcn Wu, Ellen Silva, Hui Zhu, Jin-Jae Chen, Chin-Yao Huang, Wen-Lin Tsai, and Donald Streibig for their cordial friendship and encouragement. 1 am deeply grateful to Su-Tai Wang for giving me an immediate lift to campus on the occasion that my car was dead right before my oral defense without any warning. To my mother and two younger brothers, Yang-Ping and Yang-Tai, I thank you for your understanding of my absence for the past four years and for your enormous support when times were rough for our family. To my wife, Nien-Chen, I offer sincere thanks for your unshakable faith in me and your willingness to endure with me the vicissitudes of my endeavors. VITA January 13, 1967 ................................................................ Bom - Taipei, Taiwan June 1989 ........................................................................... B.S./Animal Science National Taiwan University Taipei, Taiwan 1989-1991 .......................................................................... Second Lieutenant, Infantry Taitung, Taiwan August 1993 ...................................................................... M.S./Food Science and Nutrition The Ohio State University Columbus, Ohio 1993-Present ...................................................................... Graduate Research Associate The Ohio State University Columbus, Ohio FIELDS OF STUDY Major Field: Food Science and Technology Studies in Food Chemistry, Food Engineering, and Biochemical Engineering TABLE OF CONTENTS ACKNOWLEDGEMENT.................................................................................................... iii VITA ..................................................................................................................................... iv LIST OF TABLES................................................................................................................xni LIST OF FIGURES..............................................................................................................xiv ABSTRACT..........................................................................................................................xviii CHAPTER PAGE I. INTRODUCTION.......................................................................................................1 1.1 Background ..................................................................................................... 1 1.1.1 Xanthan gum fermentation ............................................................... 1 1.1.2 Immobilized cell bioneactor .............................................................3 1.1.3 Ultrafiltration of xanthan solution ................................................... 6 1.2 Objectives ........................................................................................................ 7 1.3 Scope of the Study .........................................................................................9 II. LITERATURE REVIEW .......................................................................................... 13 2.1 Introduction .................................................................................................... 13 2.2 Structure and Conformation of Xanthan ..................................................... 14 2.3 Characteristic Properties of Xanthan Gum .................................................18 2.3.1 Pseudoplasticity ............................................................................... 18 2.3.2 Molecular weight .............................................................................20 2.4 Microbial Biosynthesis of Xanthan Gum ....................................................22 2.4.1 Function and importance ................................................................. 22 2.4.2 Enzyme system ............................................................................... 23 2.4.3 Mechanism of biosynthesis ............................................................ 24 2.5 Fermentation Kinetics ...................................................................................26 2.5.1 Cell growth kinetics ........................................................................26 2.5.2 Product formation kinetics .............................................................29 2.5.3 Effects of environmental factors ....................................................30 2.5.3.1 Medium composition ......................................................... 31 2.5.3.2 Temperature ........................................................................ 31 2.5.3.3 pH ......................................................................................... 31 2.5.3.4 Shear ..................................................................................... 32 2.5.3.5 Dissolved oxygen ................................................................32 2.5.3.6 Other factors ........................................................................ 33 2.6 Oxygen Transfer in Xanthan Fermentation................................................33 2.6.1 Determination of volumetric mass transfer coefficient ................ 33 2.6.2 Factors affecting oxygen transfer .................................................. 35 2.7 Xanthan Production Process ........................................................................39 2.7.1 Bioreactor types .............................................................................. 41 2.7.2 Fermentation processes .................................................................. 45 2.7.3 Recovery and purification ..............................................................46 2.7.3.1 Alcohol precipitation .......................................................... 47 2.7.3.2 Freezing-thawing method ..................................................48 2.7.3.3 Other purification methods ................................................49 2.8 Cell Immobilization ......................................................................................50 vi 2.8.1 Advantages and limitations ......................... 50 2.8.1.1 Advantages .......................................................................... 50 2.8.1.2 Limitations .......................................................................... 51 2.8.1.3 Changes in cell properties .................................................. 52 2.8.2 Methods of immobilization..............................................................53
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