Preface

This book summarizes the results of more than 20 years of research on a fungus, Dec 1, which was isolated in my laboratory, as a candidate to decolorize colored substances that are visible xenobiotic pollutants and cause serious environmental problems.

Various studies have attempted to improve or change environments using biological activity, but practical examples of this technique are rare. This is mainly because of the lack of basic information and the lack of optimization in reactor systems. In this book, one possibility of using a single microorganism to resolve environmental issues related to colored substances is demonstrated.

This book is composed of six chapters, and various aspects of isolated Dec 1, including its scientific analysis and the optimization of the engineered production of enzymes responsible for decolorization, are provided in it.

The features and characteristics of Dec 1 included in this book are as follows:

1. Dec 1 has been isolated as a fungus for dye decolorization. It has been finally identified as the non-white rot fungus, Thanatephorus cucmerins Dec 1.

2. The decolorization spectrum of Dec 1 is vast, indicating that Dec 1 produces multiple enzymes that are responsible for decolorization.

3. New peroxidase DyP, Aryl Alcohol Oxidase (AAO), Manganese Peroxidase (MnP), and Versatile Peroxidase (TcVP1) have been purified from Dec 1 and characterized.

4. The gene, dyp, has been cloned from Dec 1 and expressed in the fungus, Aspergillus oryzae.

5. Recombinant DyP (rDyP) has been shown to be almost identical to DyP.

6. The unique characteristics of DyP have been verified using crystallization and X-ray analysis.

7. The immobilization of rDyP has been found to be successful only when using a new mesoporous material as a carrier.

8. The enhanced production of DyP has been attempted using liquid culture, Solid-state Culture (SSC), repeated-batch culture, and fed-batch culture.

9. To overcome the problems involved in these culture methods, an Air Membrane Surface (AMS) reactor has been introduced, and increased rDyP production has been confirmed.

10. The final level of rDyP production has been found to be more than a half million-fold higher than the original level of DyP production by T. cucumeris Dec 1.

11. Dec 1 has demonstrated efficient decolorization of molasses waste, kraft pulp bleaching effluent, and oxygen-delignified bleaching effluent.

12. As substrates for Dec 1 growth, complex media, including rice bran powder, wheat bran powder, and molasses, have been used, and the advantages of each medium have been described.

I believe that this book will provide researchers in this field with a useful resource to support current knowledge on biological decolorization and will provide students with a logical and practical scheme for approaching colored substance treatment. During my time as the Director of the Resources Recycling Process Laboratory, at the Chemical Resources Laboratory, Tokyo Institute of Technology, many researchers and graduate and undergraduate students at the campus and in private companies have helped to accomplish these results. I am indebted to the following researchers for giving me the opportunity to study Dec 1 and for offering many valuable suggestions: Drs. Y. Sugano, M. Hirai, T. Sato, M. Iwamoto, T.H. Lee, N. Uematsu, and J. Sugiura. l am also grateful to the following graduate and undergraduate students: S.J. Kim, M. Shakeri, N. Shintani, T. Shimokawa, K. Sasaki, Y. Matsushima, A. Ichiyanagi, R. Muramatu, R. Sasaki, N. Suzuki, and C. Matsuo.

I especially thank Professors T. Imanaka, Professor Emeritus of Kyoto University, and J. Takahashi, Professor Emeritus of Obihiro University of Agriculture and Veterinary Medicine, for their cooperation on this book.