food biotechnology second edition

The topics herein deal with bioconversion of food raw materials to processed products, improvement of food quality, food safety, designing of ingredients for functional foods, biochemica

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Food Biotechnology

Second Edition

FOOD SCIENCE AND TECHNOLOGY

A Series of Monographs, Textbooks, and Reference Books

Editorial Advisory Board

Gustavo V Barbosa-Cánovas Washington State University–Pullman

P Michael Davidson University of Tennessee–Knoxville Mark Dreher McNeil Nutritionals, New Brunswick, NJ Richard W Hartel University of Wisconsin–Madison Lekh R Juneja Taiyo Kagaku Company, Japan Marcus Karel Massachusetts Institute of Technology Ronald G Labbe University of Massachusetts–Amherst Daryl B Lund University of Wisconsin–Madison David B Min The Ohio State University Leo M L Nollet Hogeschool Gent, Belgium Seppo Salminen University of Turku, Finland James L Steele University of Wisconsin–Madison John H Thorngate III Allied Domecq Technical Services, Napa, CA Pieter Walstra Wageningen University, The Netherlands John R Whitaker University of California–Davis Rickey Y Yada University of Guelph, Canada

76 Food Chemistry: Third Edition, edited by Owen R Fennema

77 Handbook of Food Analysis: Volumes 1 and 2, edited by Leo M L Nollet

78 Computerized Control Systems in the Food Industry, edited by Gauri S Mittal

79 Techniques for Analyzing Food Aroma, edited by Ray Marsili

80 Food Proteins and Their Applications, edited by Srinivasan Damodaran and Alain Paraf

81 Food Emulsions: Third Edition, Revised and Expanded, edited by Stig E Friberg and Kåre Larsson

82 Nonthermal Preservation of Foods, Gustavo V Barbosa-Cánovas, Usha R Pothakamury, Enrique Palou, and Barry G Swanson

83 Milk and Dairy Product Technology, Edgar Spreer

84 Applied Dairy Microbiology, edited by Elmer H Marth and James L Steele

85 Lactic Acid Bacteria: Microbiology and Functional Aspects, Second Edition, Revised and Expanded, edited by Seppo Salminen and Atte von Wright

86 Handbook of Vegetable Science and Technology: Production, Composition, Storage, and Processing, edited by D K Salunkhe and S S Kadam

87 Polysaccharide Association Structures in Food, edited by Reginald H Walter

88 Food Lipids: Chemistry, Nutrition, and Biotechnology, edited by Casimir C Akoh and David B Min

89 Spice Science and Technology, Kenji Hirasa and Mitsuo Takemasa

90 Dairy Technology: Principles of Milk Properties and Processes, P Walstra,

T J Geurts, A Noomen, A Jellema, and M A J S van Boekel

91 Coloring of Food, Drugs, and Cosmetics, Gisbert Otterstätter

92 Listeria, Listeriosis, and Food Safety: Second Edition, Revised and Expanded, edited by Elliot T Ryser and Elmer H Marth

93 Complex Carbohydrates in Foods, edited by Susan Sungsoo Cho, Leon Prosky, and Mark Dreher

94 Handbook of Food Preservation, edited by M Shafiur Rahman

95 International Food Safety Handbook: Science, International Regulation, and Control, edited by Kees van der Heijden, Maged Younes, Lawrence Fishbein, and Sanford Miller

96 Fatty Acids in Foods and Their Health Implications: Second Edition, Revised and Expanded, edited by Ching Kuang Chow

97 Seafood Enzymes: Utilization and Influence on Postharvest Seafood Quality, edited by Norman F Haard and Benjamin K Simpson

98 Safe Handling of Foods, edited by Jeffrey M Farber and Ewen C D Todd

99 Handbook of Cereal Science and Technology: Second Edition, Revised and Expanded, edited by Karel Kulp and Joseph G Ponte, Jr.

100 Food Analysis by HPLC: Second Edition, Revised and Expanded, edited by Leo M L Nollet

101 Surimi and Surimi Seafood, edited by Jae W Park

102 Drug Residues in Foods: Pharmacology, Food Safety, and Analysis, Nickos A Botsoglou and Dimitrios J Fletouris

103 Seafood and Freshwater Toxins: Pharmacology, Physiology, and Detection, edited by Luis M Botana

104 Handbook of Nutrition and Diet, Babasaheb B Desai

105 Nondestructive Food Evaluation: Techniques to Analyze Properties and Quality, edited by Sundaram Gunasekaran

106 Green Tea: Health Benefits and Applications, Yukihiko Hara

107 Food Processing Operations Modeling: Design and Analysis, edited by Joseph Irudayaraj

108 Wine Microbiology: Science and Technology, Claudio Delfini and Joseph V Formica

109 Handbook of Microwave Technology for Food Applications, edited by Ashim K Datta and Ramaswamy C Anantheswaran

110 Applied Dairy Microbiology: Second Edition, Revised and Expanded, edited by Elmer H Marth and James L Steele

111 Transport Properties of Foods, George D Saravacos and Zacharias B Maroulis

112 Alternative Sweeteners: Third Edition, Revised and Expanded, edited by Lyn O’Brien Nabors

113 Handbook of Dietary Fiber, edited by Susan Sungsoo Cho and Mark L Dreher

114 Control of Foodborne Microorganisms, edited by Vijay K Juneja and John N Sofos

115 Flavor, Fragrance, and Odor Analysis, edited by Ray Marsili

116 Food Additives: Second Edition, Revised and Expanded, edited by A Larry Branen,

P Michael Davidson, Seppo Salminen, and John H Thorngate, III

117 Food Lipids: Chemistry, Nutrition, and Biotechnology: Second Edition, Revised and Expanded, edited by Casimir C Akoh and David B Min

118 Food Protein Analysis: Quantitative Effects on Processing, R K Owusu-Apenten

119 Handbook of Food Toxicology, S S Deshpande

120 Food Plant Sanitation, edited by Y H Hui, Bernard L Bruinsma,

J Richard Gorham, Wai-Kit Nip, Phillip S Tong, and Phil Ventresca

121 Physical Chemistry of Foods, Pieter Walstra

122 Handbook of Food Enzymology, edited by John R Whitaker, Alphons G J Voragen, and Dominic W S Wong

123 Postharvest Physiology and Pathology of Vegetables: Second Edition, Revised and Expanded, edited by Jerry A Bartz and Jeffrey K Brecht

124 Characterization of Cereals and Flours: Properties, Analysis, and Applications, edited by Gönül Kaletunç and Kenneth J Breslauer

125 International Handbook of Foodborne Pathogens, edited by Marianne D Miliotis and Jeffrey W Bier

126 Food Process Design, Zacharias B Maroulis and George D Saravacos

127 Handbook of Dough Fermentations, edited by Karel Kulp and Klaus Lorenz

128 Extraction Optimization in Food Engineering, edited by Constantina Tzia and George Liadakis

129 Physical Properties of Food Preservation: Second Edition, Revised and Expanded, Marcus Karel and Daryl B Lund

130 Handbook of Vegetable Preservation and Processing, edited by Y H Hui, Sue Ghazala, Dee M Graham, K D Murrell, and Wai-Kit Nip

131 Handbook of Flavor Characterization: Sensory Analysis, Chemistry, and Physiology, edited by Kathryn Deibler and Jeannine Delwiche

132 Food Emulsions: Fourth Edition, Revised and Expanded, edited by Stig E Friberg, Kare Larsson, and Johan Sjoblom

133 Handbook of Frozen Foods, edited by Y H Hui, Paul Cornillon, Isabel Guerrero Legarret, Miang H Lim, K D Murrell, and Wai-Kit Nip

134 Handbook of Food and Beverage Fermentation Technology, edited by Y H Hui, Lisbeth Meunier-Goddik, Ase Solvejg Hansen, Jytte Josephsen, Wai-Kit Nip, Peggy S Stanfield, and Fidel Toldrá

135 Genetic Variation in Taste Sensitivity, edited by John Prescott and Beverly J Tepper

136 Industrialization of Indigenous Fermented Foods: Second Edition, Revised and Expanded, edited by Keith H Steinkraus

137 Vitamin E: Food Chemistry, Composition, and Analysis, Ronald Eitenmiller and Junsoo Lee

138 Handbook of Food Analysis: Second Edition, Revised and Expanded, Volumes 1, 2, and 3, edited by Leo M L Nollet

139 Lactic Acid Bacteria: Microbiological and Functional Aspects: Third Edition, Revised and Expanded, edited by Seppo Salminen, Atte von Wright, and Arthur Ouwehand

140 Fat Crystal Networks, Alejandro G Marangoni

141 Novel Food Processing Technologies, edited by Gustavo V Barbosa-Cánovas,

M Soledad Tapia, and M Pilar Cano

142 Surimi and Surimi Seafood: Second Edition, edited by Jae W Park

143 Food Plant Design, Antonio Lopez-Gomez; Gustavo V Barbosa-Cánovas

144 Engineering Properties of Foods: Third Edition, edited by M A Rao, Syed S.H Rizvi, and Ashim K Datta

145 Antimicrobials in Food: Third Edition, edited by P Michael Davidson, John N Sofos, and A L Branen

146 Encapsulated and Powdered Foods, edited by Charles Onwulata

147 Dairy Science and Technology: Second Edition, Pieter Walstra, Jan T M Wouters and Tom J Geurts

148 Food Biotechnology, Second Edition, edited by Kalidas Shetty, Gopinadhan Paliyath, Anthony Pometto and Robert E Levin

149 Handbook of Food Science, Technology, and Engineering - 4 Volume Set, edited by Y H Hui

150 Thermal Food Processing: New Technologies and Quality Issues, edited by Da-Wen Sun

151 Aflatoxin and Food Safety, edited by Hamed K Abbas

152 Food Packaging: Principles and Practice, Second Edition, Gordon L Robertson

Food Biotechnology

Second Edition

edited by

Kalidas Shetty Gopinadhan Paliyath Anthony Pometto Robert E Levin

A CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa plc.

Boca Raton London New York

Published in 2006 by

CRC Press

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© 2006 by Taylor & Francis Group, LLC

CRC Press is an imprint of Taylor & Francis Group

No claim to original U.S Government works

Printed in the United States of America on acid-free paper

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is the Academic Division of T&F Informa plc.

Major challenges facing the world today are not just those of food production and food

quality for meeting protein and calorie needs (basic nutritional needs), but also those

related to better health A significant challenge is the outbreak of oxidation-linked disease

epidemics caused by calorie sufficiency and excess calories This nutritional epidemic is

occurring not only in the developed world, but also in newly industrialized countries such

as China, Brazil, Mexico, and India, which have the most rapidly growing type 2 diabetes

problem in the world Because diabetes is tied to other oxidation-linked diseases such as

cardiovascular disease (CVD) and cancer, it will inevitably place a tremendous burden on

the emerging health-care systems of these countries This situation will place further strain

and pressure on existing health-care challenges such as treatment of infectious diseases

like AIDS, tuberculosis, and foodborne illnesses among lower income populations In the

more developed countries, the continuous and steady advancement of obesity and its

sub-sequent consequences of increases in diabetes, CVD, and cancer are posing additional

challenges All major health challenges, be they of calorie sufficiency- or calorie

insuffi-ciency-linked infectious diseases, are directly or indirectly related to diet and

environmen-tally linked disease Therefore, technologies for disease chemoprevention through dietary

modification (reduced calorie intake with more fruits and vegetables and novel ingredients

from other food-grade biological and microbial systems) will be very important to help

manage these emerging health-care challenges In addition, advances in food

biotechnol-ogy must be more nutritionally relevant and must consider the environmental impacts and

consequences of food production and consumption

Thus, with these critical issues in mind, Food Biotechnology, 2nd Edition, has been

assembled with the hope of being an authoritative, comprehensive, conceptually sound, and

highly informative compilation of recent advances in various important areas of food

bio-technology The topics herein deal with bioconversion of food raw materials to processed

products, improvement of food quality, food safety, designing of ingredients for functional

foods, biochemical advances in traditional fermentation, and, most importantly, they

pro-vide an international perspective to the whole field Biotechnology has become an

impor-tant tool in recent years, and several scientists across the world are investigating advanced

and novel biological, cellular, molecular, and biochemical strategies for improving food

production and processing, for enhancing food safety and quality, and for improving from

organoleptic to functional aspects of food and food ingredients for better human health

Thus, this volume has amassed diverse topics from appropriate experts in specific areas

from across the globe The book is divided into three sections The first section deals with

food microbiology, the second with plant and animal food applications and functional

foods, and the third section deals with food safety, novel bioprocessing, traditional

fermen-tations, and regulatory and patent issues at an international level In all, there are 70

chap-ters covering key areas of food biotechnology within the three sections The first 20

chapters in Section 1, dealing with food microbiology, provide in-depth accounts of basic

principles of microbiology, fermentation technologies, aspects of genetic engineering for

production of various food ingredients, and several other specialized topics involving

microbial systems Section 2, comprising 27 chapters, is quite diverse and deals with plant

tissue culture techniques, genetic engineering of plants and animals, functional food

ingre-dients and their health benefits, probiotics, antibody production for oral vaccines, and

several topics on enzyme technologies Section 3, with 23 chapters, is quite diverse and

examines several aspects of food safety issues, bioprocessing, and fermentation

biotech-nologies used across the globe In essence, this book has brought together diverse areas of

food biotechnology with a strong focus on biochemistry and molecular biology, and it is

unique in that respect This strong molecular- and biochemically based conceptual

view-point provided by many chapters will form the basis for development of food

biotechnol-ogy over the next few decades, particularly in the context of designing food ingredients for

better health and microbial food safety

The editors wish to thank all the authors for their outstanding efforts to document and present their research and their conceptual information about their current understand-

ing of this field Their efforts have particularly advanced our conceptual knowledge with

regard to food safety, novel microbial processing, novel applications of plant foods and

ingredients, and functional food ingredients

The editors also would like to thank the staff of Marcel Dekker, CRC, and Taylor and Francis for their help and support in the timely publication of this 2nd edition, and

particularly for coordinating the work of the authors of 70 chapters across several

coun-tries All these efforts have advanced the frontiers of food biotechnology and have given it

a stronger molecular, metabolic, biochemical, and nutritionally relevant emphasis that is

conceptually applicable in any part of the world

The Editorial Board

Dr Kalidas Shetty is a professor of food biotechnology in the Department of Food

Science at the University of Massachusetts-Amherst He received his BS degree from the

University of Agricultural Sciences, Bangalore, India, majoring in applied microbiology,

and MS and PhD from the University of Idaho, Moscow in microbiology He then pursued

postdoctoral studies in plant biotechnology in Japan (National Institute of Agro-Biological

Sciences, Tsukuba Science City) and Canada (University of Guelph) prior to joining the

University of Massachusetts in 1993

Dr Shetty’s research interests focus on redox pathway-linked biochemical tion of phenolic phytochemicals in food botanicals using novel tissue culture, seed sprout,

regula-and fermentation systems This focus is contributing to innovative advances in the areas of

nutraceuticals, functional foods, and food antimicrobial strategies In particular, the

sus-ceptibility of bacterial food pathogens to phenolic phytochemicals at low pH through

redox-linked pathways is his major interest in developing new food safety strategies He

has published over 100 manuscripts in peer-reviewed journals and over 25 as invited

reviews and in conference proceedings He holds four United States patents

Dr Shetty was appointed as the editor of the journal Food Biotechnology, published

by Marcel Dekker (now Taylor and Francis) He is also on the editorial board of three

additional journals in the areas of food and environmental sciences

In 2004, Professor Shetty was selected by the U.S State Department as a Jefferson Science Fellow to advise the Bureau of Economic and Business Affairs on scientific issues

as they relate to international diplomacy and international development This program,

administered by the U.S National Academies, allowed Dr Shetty to serve as science

advi-sor at the U.S State Department for 1 year in 2004–2005, and he will continue to serve as

science advisor for 5 more years following his return to the University of Massachusetts

Dr Shetty has widely traveled and has been invited to present lectures and seminars in the

areas of food biotechnology, functional foods and dietary phytochemicals, and food safety

in over 20 countries in Asia, Europe, and the Americas In 1998 he was awarded the

Asia-Pacific Clinical Nutrition Society Award for his contributions to the area of

phytochemi-cals, functional foods, and human health based on his understanding of Asian food

traditions At the University of Massachusetts he has won the College of Food and Natural

Resources Outstanding Teaching Award and a Certificate of Achievement for Outstanding

Outreach Contributions

Dr Anthony L Pometto is a professor of industrial microbiology in the Department of

Food Science and Human Nutrition at Iowa State University He received his BS degree in

biology from George Mason University, Fairfax, Virginia, and his MS and PhD in

bacteri-ology from the University of Idaho, Moscow, Idaho Dr Pometto worked as a full-time

scientific aide in the Department of Bacteriology and Biochemistry at the University of

Idaho for twelve years He joined the faculty at Iowa State University in 1988

Dr Pometto’s research interests focus on microbial degradation of degradable tics, bioconversion of agricultural commodities into value-added products via fermentation,

plas-development of novel bioreactors, production of enzymes for the food industry, and the

utilization of food industrial wastes He has co-authored over 60 peer-reviewed journal

articles and over 25 articles as invited reviews, book chapters, and conference proceedings

He is a co-inventor on three United States patents He is also a member of editorial board

of the journal Food Biotechnology, published by Marcel Dekker (now Taylor and Francis).

Dr Pometto became director of the NASA Food Technology Commercial Space Center at Iowa State University in 2000 The Center is associated with the NASA Johnson

Space Center, Houston, Texas, which manages all the food systems for the shuttle,

International Space Center, and planetary exploration missions The NASA Food

Technology Commercial Space Center at Iowa State University was founded in August

1999 and has the mission to engage industry and academia to develop food products and

processes that will benefit NASA and the public The specific objectives are as follows: (1)

to develop food products that meet the shelf life requirements for the shuttle, ISS and the

planetary outpost, which are nine months, one year, and five years, respectively; (2) to

develop equipment and process technologies to convert the proposed over 15 crops grown

on the planetary outpost, Moon or Mars, into safe, edible foods; and (3) to build

partner-ships with food companies to develop these new food products and processes to make

them available for NASA utilization The space food challenges being addressed by the

Center’s commercial partners and affiliate faculty are development of new food products,

development of new food processing equipment, extending the shelf life of foods,

improv-ing and monitorimprov-ing food safety, packagimprov-ing of foods, development of food waste

manage-ment systems, and developmanage-ment of disinfection systems for space travel For more

information, please see the web site http://www.ag.iastate.edu/centers/ftcsc/

Dr Pometto has recently been named associate director of the Iowa State University Institute for Food Safety and Security, which was created in 2002 as one of six presidential

academic initiatives Dr Pometto works with the Institute’s director, Dr Manjit Misra, to

bring together the research, education, and outreach components of food safety and

secu-rity at Iowa State University into one umbrella institute for the purposes of efficient

team-work that is well-positioned among government, industry, and producers

Dr Gopinadhan Paliyath is an associate professor at the Department of Plant Agriculture,

University of Guelph, Ontario, Canada Dr Paliyath has a very broad background in plant

science, with a specialization in biochemistry He obtained his BS Ed degree (botany and

chemistry) in science education from the University of Mysore, MS degree (botany) from

the University of Calicut, and PhD degree (biochemistry) from the Indian Institute of

Science, Bangalore He did postdoctoral work at Washington State University, the

University of Waterloo, and the University of Guelph

The focus of Dr Paliyath’s current research is in the areas of post-harvest biology and technology, functional foods, and nutraceuticals He is investigating the signal trans-

duction events in response to ethylene and the role of phospholipase D in such events

Various aspects dealing with improvement in fruit and vegetable shelf life and quality, and

the efficacy of functional food ingredients are also being investigated Technologies and

products have been developed for enhancing the shelf life and quality of fruits, vegetables,

and flowers based on phospholipase D inhibition (US Patent #6,514,914) As well, he is

developing novel technologies for the isolation of active nutraceutical fractions and the use

of nutraceuticals to enhance the functional food value of processed fruits and vegetables

Phospholipase D inhibition technology for fruit and vegetable preservation has been

licensed for commercialization His current research also includes investigations into the

mechanism of action of nutraceuticals (grape and wine polyphenols) as cancer

University of FloridaGainesville, Florida, USA

Michele Del Carlo

Dipartimento di Scienze degli Alimenti Università di Teramo

Teramo, Italy

Tamara Casci

School of Food BiosciencesThe University of ReadingWhiteknights, UK

Feng Chen

Department of Botany

The University of Hong Kong

Hong Kong, China

Thomas T Chen

Department of Molecular and Cell Biology

University of Connecticut

Storrs, Connecticut, USA

Pinwen Peter Chiou

Department of Molecular and Cell Biology

University of Connecticut

Storrs, Connecticut, USA

Hanne Risager Christensen

BioCentrum-DTU

Biochemistry and Nutrition

The Technical University of Denmark

Centre for Chemistry and Chemical

Engineering, Lund University

Lund, Sweden

Ali Demirci

Deptartment of Agricultural and

Biological Engineering

The Hucks Institute of Life Sciences

Pennsylvania State University

University Park, Pennsylvania, USA

Hortense Dodo

Food Biotechnology Laboratory

Department of Food & Animal Sciences

Alabama Agricultural and Mechanical

University

Normal, Alabama, USA

Gilles Feron

Laboratoire de MicrobiologieUMR UB INRA

Ensbana, Dijon, France

of Denmark Kgs Lyngby, Denmark

Glenn R Gibson

School of Food BiosciencesThe University of ReadingWhiteknights, UK

Ramon Gonzalez

Departments of Chemical Engineering and Food Science

& Human NutritionIowa State UniversityAmes, Iowa, USA

Rajni Hatti-Kaul

Department of BiotechnologyCenter for Chemistry and Chemical Engineering

Lund UniversityLund, Sweden

Department of Metabolic Biology

John Innes Centre

Norwich Research Park

Plant Cell Biotechnology Department

Central Food Technological Research

Teagasc, Dairy Products Research Centre

Fermoy, County Cork, Ireland

Anthony J Kinney

Crop Genetics Research and Development

DuPont Experimental Station

Wilmington, Delware, USA

Harry H Klee

Horticultural Sciences Department Institute of Food and Agricultural Sciences

University of FloridaGainesville, Florida, USA

Jeffrey D Klucinec

BASF Plant ScienceAmes ResearchAmes, Iowa, USA

Koffi Konan

Food Biotechnology LaboratoryDepartment of Food & Animal SciencesAlabama A&M University

Normal, Alabama, USA

Reinhard Krämer

Institute of BiochemistryUniversity of KölnZülpicher, Germany

Hordur G Kristinsson

Department of Food Science and Human Nutrition

University of FloridaGainesville, Florida, USA

Robert E Levin

Department of Food ScienceUniversity of MassachusettsAmherst, Massachusetts, USA

Michigan State University

East Lansing, Michigan, USA

Xue-Jun Liu

Department of Botany

The University of Hong Kong

Hong Kong, China

John R Lupien

Department of Food Science

University of Massachusetts

Amherst, Massachusetts, USA

Evelyn Mae Tecson-Mendoza

Institute of Plant Breeding, College of

School of Food Biosciences

The University of Reading

Lund UniversityLund, Sweden

Patrick P McCue

Program in Molecular and Cellular Biology

University of MassachusettsAmherst, Massachusetts, USA

Lynne McLandsborough

Food Science DepartmentUniversity of MassachusettsAmherst, Massachusetts, USA

Michael J Miller

Department of Food ScienceNorth Carolina State UniversityRaleigh, North Carolina, USA

Yoshinori Mine

Department of Food Science University of GuelphGuelph, Ontario, Canada

Mysore, India

Kendra Kerr Nightingale

Department of Food ScienceCornell University

Ithaca, New York, USA

Horticultural Sciences Department

Institute of Food and Agricultural

Sciences, University of Florida

Gainesville, Florida, USA

Neftali Ochoa-Alejo

Unit of Biotechnology and Plant Genetic

Engineering

Center of Research and Advanced Studies

National Polytechnic Institute

Irapuato, Gto., Mexico

Lagos State University

Ojo, Lagos, Nigeria

Gabriela Olmedo

Departamento de Ingeniería Genética de

Plantas

Centro de Investigación y de Estudios

Avanzados del IPN

Departamento de Ingeniería Genética

de Plantas, Centro de Investigación y de Estudios Avanzados del IPN

Unidad Irapuato, Gto., México

Eugenio Perez-Molphe

Chemistry DepartmentCenter of Basic SciencesAutonomous University of Aguascalientes

Ags, Mexico

Reena Grittle Pinhero

Department of Food ScienceUniversity of GuelphGuelph, Ontario, Canada

Anthony L Pometto

Department of Food Science and Human Nutrition, NASA Food Technology Commercial Space Center

Iowa State UniversityAmes, Iowa, USA

Jose Antonio Prieto

Department of BiotechnologyInstituto de Agroquímica y Tecnología

de losAlimentos, Valencia, Spain

Vernon G Pursel

U S Department of Agriculture

Agricultural Research Service

Beltsville Agricultural Research Center

Biotechnology and Germplasm

Laboratory

Beltsville, Maryland, USA

Nasib Qureshi

United States Department of Agriculture

National Center for Agricultural Utilization

Fermentation/Biotechnology Research

Peoria, Illinois, USA

A Eugene Raj

Fermentation Technology & Bioengineering

Central Food Technological Research

Institute

Mysore, India

Sumitra Ramachandran

Department of Chemical and Biochemical

Engineering, University Blaise Pascal

Human Resource Development

Department of Food Microbiology

Central Food Technological Research

Institute

Mysore, India

Robert A Rastall

School of Food Biosciences

The University of Reading

Mysore, India

G.A Ravishankar

Plant Cell Biotechnology DepartmentCentral Food Technological Research Institute

Mysore, India

T Ritu

Plant Cell Biotechnology DepartmentCentral Food Technology Research Institute

R Sarada

Plant Cell Biotechnology DepartmentCentral Food Technological Research Institute

Pioneer Valley Life Sciences Institute

Springfield, Massachusetts, USA

B Suresh

Plant Cell Biotechnology Department

Central Food Technology Research

Agricultural University of Athens

Iera Odos, Athens, Greece

Joseph Tulpinski

N-terminus Research Laboratory

Pomona, California, USA

S Umesh-Kumar

Department of Food Microbiology

Central Food Technological Research

Institute

Mysore, India

Ragip Unal

N-terminus Research Laboratory

Pomona, California, USA

K.S Venkatesh

Department of Food MicrobiologyCentral Food Technological Research Institute

Mysore, India

S.V.N Vijayendra

Department of Food Microbiology Central Food Technological Research Institute

Mysore, India

Olga Viquez

Food Biotechnology Laboratory Department of Food and Animal SciencesAlabama Agricultural and Mechanical University

Normal, Alabama, USA

Y Waché

Laboratoire de MicrobiologieUMR UB INRA

Ensbana, Dijon, France

Randy W Worobo

Department of Food Science and

Technology, New York State Agricultural

Experiment Station, Cornell University

Geneva, New York, USA

James P Wynn

Martek Biosciences Corporation

Columbia, Maryland, USA

Glenview, Illinois, USA

SECTION 1 FOOD MICROBIOLOGY 1

Chapter 1.01 Food Microbiology 3

Robert E Levin

Chapter 1.02 Principles of Biochemistry and Molecular Biology 19

Patrick P McCue and Kalidas Shetty

Chapter 1.03 Fermentation Technology and Bioreactor Design 33

A Eugene Raj and N.Ganesh Karanth

Chapter 1.04 Process Developments in Solid-State Fermentation for

Food Applications 87

Ashok Pandey and Sumitra Ramachandran

Chapter 1.05 Metabolic Engineering of Bacteria for Food Ingredients 111

Ramon Gonzalez

Chapter 1.06 Technologies Used for Microbial Production of Food Ingredients 131

Anthony L Pometto III and Ali Demirci

Chapter 1.07 Production of Carotenoids by Gene Combination in

Escherichia coli 143 Gerhard Sandmann

Chapter 1.08 Production of Amino Acids: Physiological and

Genetic Approaches 155

Reinhard Krämer

Chapter 1.09 Biotechnology of Microbial Polysaccharides in Food 193

Ian W Sutherland

Chapter 1.10 Genetics of Dairy Starter Cultures 221

Daniel J O’ Sullivan

Chapter 1.11 Genetic Engineering of Baker’s Yeast: Challenges and Outlook 245

Jose Antonio Prieto, Jaime Aguilera, and Francisca Randez-Gil

Chapter 1.12 The Biotechnology of Wine Yeast 281

Linda F Bisson

Chapter 1.13 Stress Tolerance, Metabolism, and Development:

The Many Flavors of Trehalose 311

Mike A Singer, Tiago F Outeiro, and Susan Lindquist

Chapter 1.14 Production of Pectinases and Utilization in Food Processing 329

K.S Venkatesh and S Umesh-Kumar

Chapter 1.15 Biotechnology of Citric Acid Production 349

T Roukas

Chapter 1.16 Microbial Biotechnology of Food Flavor Production 407

G Feron and Y Waché

Chapter 1.17 Microbial Production of Oils and Fats 443

James P Wynn and Colin Ratledge

Chapter 1.18 Potential Uses of Cyanobacterial Polysaccharides

in the Food Industry 473

Xue-Jun Liu and Feng Chen

Chapter 1.19 Food Applications of Algae 491

G.A Ravishankar, R Sarada, B Sandesh Kamath, and K.K Namitha

Chapter 1.20 Butanol Production from Agricultural Biomass 525

Nasib Qureshi and Hans P Blaschek

SECTION 2 PLANT AND ANIMAL FOOD APPLICATIONS AND

FUNCTIONAL FOODS 551

Chapter 2.01 Methods in Plant Tissue Culture 553

Hector G Nunez-Palenius, Daniel J Cantliffe, Harry H Klee, Neftali Ochoa-Alejo, Rafael Ramirez-Malagon, and Eugenio Perez-Molphe

Chapter 2.02 Clonal Screening and Sprout Based Bioprocessing of Phenolic

Phytochemicals for Functional Foods 603

Kalidas Shetty, Fergus M Clydesdale, and Dhiraj A Vattem

Chapter 2.03 Genomic Basics for Food Improvement 627

Gabriela Olmedo, Socorro Parra, and Plinio Guzmán

Chapter 2.04 Molecular Design of Soybean Proteins for Enhanced

Food Quality 649

Nobuyuki Maruyama, Evelyn Mae Tecson-Mendoza, Yukie Maruyama, Motoyasu Adachi, and Shigeru Utsumi

Chapter 2.05 Genetic Modification of Plant Starches for Food Applications 675

Jeffrey D Klucinec and Peter L Keeling

Chapter 2.06 Bioprocessing of Starch Using Enzyme Technology 709

K Ravi-Kumar and S Umesh-Kumar

Chapter 2.07 Genetic Modification of Plant Oils for Food Uses 723

Anthony J Kinney

Chapter 2.08 Molecular Biotechnology for Nutraceutical Enrichment

of Food Crops: The Case of Minerals and Vitamins 735

Octavio Paredes-López and Juan Alberto Osuna-Castro

Chapter 2.09 Potential Health Benefits of Soybean Isoflavonoids and

Related Phenolic Antioxidants 771

Patrick P McCue and Kalidas Shetty

Chapter 2.10 Functional Phytochemicals from Cranberries: Their Mechanism

of Action and Strategies to Improve Functionality 789

Dhiraj A Vattem and K Shetty

Chapter 2.11 Rosmarinic Acid Biosynthesis and Mechanism of Action 825

Kalidas Shetty

Antioxidants in the Fava Bean (Vicia faba) 847 Kalidas Shetty, Reena Randhir, and Preethi Shetty

Chapter 2.13 Phytochemicals and Breast Cancer Chemoprevention 867

Sallie Smith-Schneider, Louis A Roberts, and Kalidas Shetty

Chapter 2.14 Biotechnology in Wine Industry 899

Moustapha Oke, Gopinadhan Paliyath, and K Helen Fisher

Chapter 2.15 Biotechnology of Nonnutritive Sweeteners 915

Reena Randhir and Kalidas Shetty

Chapter 2.16 Biotechnological Approaches to Improve Nutritional Quality

and Shelf Life of Fruits and Vegetables 933

Reena Grittle Pinhero and Gopinadhan Paliyath

Chapter 2.17 Genetic Modification of Peanut as a Solution to Peanut Allergy 969

Hortense Dodo, Koffi Konan, and Olga Viquez

Chapter 2.18 Recombinant Lipoxygenases and Oxylipin Metabolism in

Relation to Food Quality 989

Rod Casey and Richard K Hughes

Chapter 2.19 Genetic Modification of Production Traits in Farm Animals 1021

Vernon G Pursel

Chapter 2.20 Enzyme Technology for the Dairy Industry 1039

Kieran Kilcawley

Chapter 2.21 Egg Yolk Antibody Farming for Passive Immunotherapy 1067

Jennifer Kovacs-Nolan and Yoshinori Mine

Chapter 2.22 Application of Transgenic Fish Technology in

Sea Food Production 1087

Pinwen Peter Chiou, Jenny Khoo, and Thomas T Chen

Chapter 2.23 The Production, Properties, and Utilization of Fish Protein

Hydrolysates 1109

Hordur G Kristinsson

Chapter 2.24 Human Gut Microflora in Health and Disease:

Focus on Prebiotics 1133

Tamara Casci, Robert A Rastall, and Glenn R Gibson

Chapter 2.25 Immunomodulating Effects of Lactic Acid Bacteria 1167

Hanne Risager Christensen and Hanne Frøkiær

Chapter 2.26 Biochemical Markers for Antioxidant Functionality 1205

Dhiraj A Vattem and K Shetty

Chapter 2.27 Enzymatic Synthesis of Oligosaccharides: Progress

and Recent Trends 1229

V Maitin and R A Rastall

SECTION 3 FOOD SAFETY, NOVEL BIOPROCESSING,

TRADITIONAL FERMENTATIONS, AND REGULATORY ISSUES 1257

Chapter 3.01 Molecular Evolution and Diversity of Food Borne Pathogens 1259

Katy Windham, Kendra Kerr Nightingale, and Martin Wiedmann

Chapter 3.02 Genetics and Physiology of Pathogenicity in Food Borne

Bacterial Pathogens 1293

Michael Gray and Kathryn J Boor

Chapter 3.03 Biofilm Production by Listeria monocytogenes 1329

William K Shaw, Jr and Lynne McLandsborough

Chapter 3.04 Application of Microbial Molecular Techniques to Food Systems 1343

Robert E Levin

Chapter 3.05 Control of Food Borne Bacterial Pathogens in Animals

and Animal Products through Microbial Antagonism 1359

Mindy M Brashears, Alejandro Amezquita, and Divya Jaroni

Chapter 3.06 Bacteriocins: Antimicrobial Activity and Applications 1391

A Satyanarayan Naidu, Ragip Unal, and Joseph Tulpinski

Chapter 3.07 Genetic Characterization of Antimicrobial Peptides 1439

Haijing Hu, Matthew M Moake, and Randy W Worobo

Chapter 3.08 Phenolic Antimicrobials from Plants for Control

of Bacterial Pathogens 1479

Kalidas Shetty and Yuan-Tong Lin

Chapter 3.09 Genetic Mechanisms Involved in Regulation

of Mycotoxin Biosynthesis 1505

Michael J Miller and John E Linz

Chapter 3.10 Application of ELISA Assays for Detection and

Quantitation of Toxins in Foods 1543

Robert E Levin

Chapter 3.11 Biosensors for Food Quality Assessment 1567

Michele Del Carlo, Mihaela Nistor, Dario Compagnone,

Bo Mattiasson, and Elisabeth Csöregi

Chapter 3.12 Enzymatic Bioprocessing of Tropical Seafood Wastes 1605

Rupsankar Chakrabarti

Chapter 3.13 Cold Active Enzymes in Food Processing 1631

Rajni Hatti-Kaul, Hákon Örn Birgisson, and Bo Mattiasson

Chapter 3.14 Biotransformations as Applicable to Food Industries 1655

B Suresh, T Ritu and G A Ravishankar

Chapter 3.15 Solid-State Bioprocessing for Functional Food Ingredients

and Food Waste Remediation 1691

Kalidas Shetty

Chapter 3.16 Fermentation Biotechnology of Traditional Foods of Africa 1705

N A Olasupo

Chapter 3.17 Fermentation Biotechnology of Traditional Foods of China 1741

Zuoxing Zheng, Changlu Wang, and Yang Zheng

Chapter 3.18 Fermentation Biotechnology of Traditional Foods

of the Indian Subcontinent 1759

E Rati Rao, S.V.N Vijayendra, and M.C Varadaraj

Chapter 3.19 Fermentation Biotechnology of Plant Based Traditional

Foods of the Middle East and Mediterranean Region 1795

Parthena Kotzekidou and Effie Tsakalidou

Chapter 3.20 Fermentation Biotechnology of Animal Based Traditional

Foods of the Middle East and Mediterranean Region 1829

Effie Tsakalidou and Parthena Kotzekidou

Chapter 3.21 Anaerobic Processes for the Treatment of Food

Processing Wastes 1873

Roger A Korus

Chapter 3.22 International Aspects of the Quality and Safety

Assessment of Foods Derived by Modern Biotechnology 1895

John R Lupien

Chapter 3.23 Patenting Inventions in Food Biotechnology 1905

R Stephen Crespi

Section 1

Food Microbiology

1.5 Metabolic Control for Enhanced Metabolite Production 11

1.6 Mutagenesis for Overproduction of Metabolites 12

1.9 Aspects of Microbial Evolution 15

References 16

1.1 INTRODUCTION

Food biotechnology integrates biochemistry, chemistry, microbiology, and chemical

engi-neering for the enhanced production of food products The application of microbiology to

food systems encompasses methods involved in the assessment of microbial food safety

and the use of microorganisms for the production of foods and beverages, food products,

food additives Microorganisms involved either directly or indirectly with food systems

include bacteria, molds, yeasts, and algae Each of these microbial groups has unique

metabolic aspects that are either utilized or circumvented to achieve optimization of

vari-ous microbial processes

1.2 GENERAL ASPECTS

1.2.1 Applications of Microbiology to Foods

Ancient Egyptians used fermentation to produce beer and convert grape juice to wine

They also practiced the aerobic conversion of the alcohol in wine to the acetic acid of

vinegar, and the leavening of bread The present practices of using, for example,

pectin-ases for enhanced release of fruit juices from tissue and amylpectin-ases for the enzymatic

modification of starches, are examples involving the indirect application of

microorgan-isms to foods and food components The production of xanthan gum by the plant

patho-genic bacterium Xanthomonas campestris for use as a viscosity agent in beverages and

semisolid food products is an example of the use of an originally undesirable organism for

the production of a desirable food and beverage additive The use of the mold Aspergillus

niger to produce high yields of citric acid as a food and beverage acidulant was established

in the 1920s and is a classic example of an initial surface culture process that was

eventu-ally converted to a submerged aerated process with the use of mutants

1.2.2 The Nature of Microorganisms

Microscopic organisms are presently divided into three major groups: (1) Eubacteria

(bac-teria), which lack a discernible nucleus and mitochondria; (2) Archaebacteria (bac(bac-teria),

which also lack a discernible nucleus and mitochondria; and (3) Eukaryotes (yeasts,

molds, algae, and protozoa), which possess both a clearly discernible nucleus and

mito-chondria, plus filamentous structures known as endothelial reticulum Mitochondria are

self-replicating organelles and contain their own deoxyribonucleic acid (DNA), referred to

as mitochondrial DNA In Eukaryotes, the cytochrome and tricarboxylic acid (TCA)

enzymes required for aerobic synthesis of ATP are located in the mitochondrial membrane,

while with prokaryotes and Archaebacteria the cytochromes are in the cytoplasmic

mem-brane and the TCA enzymes are in the cytoplasm

All microorganisms are allocated to a specific group with respect to growth perature Obligate psychrophiles are defined as those organisms capable of growth at or

Hyperthermophiles are organisms from oceanic thermal vents and hot springs that are

isolated from foods

Food Microbiology 5

1.3 FUNGI

1.3.1 Fungal Cell Walls

The fungal cell wall is composed mainly of carbohydrates together with some protein and

lipids The cytoplasmic membrane, unlike the membrane of bacteria, contains sterols The

most important carbohydrates are mannan, glucan, chitin, and cellulose The wall of some

molds is primarily a chitin–glucan structure, whereas mannan is more predominant in yeasts,

resulting in mannan–chitin or mannan–glucan cell wall structures The digestive juice of the

garden snail Helix pomatia, available commercially as glusulase, is high in β-1, 3- and β-1,

6-glucanase activity and is frequently used to digest the cell wall of molds and some yeasts

Novozyme 234 (Novo Industries) will yield protoplasts of Aspergillus and Penicillium (1)

Novozyme 234 is notably effective for digesting the cell wall of Schizosaccharomyces

pombe, while glusulase Nee-154 (DuPont; Endo Laboratories) is used with Saccharomyces

cerevisiae Both Novozyme 234 and the yeast lytic enzyme from Arthrobacter luteus (ICN

Biomedicals), otherwise known as lyticase or zymolase (Sigma), are effective for yielding

spheroplasts of Yarrowia lipolytica (formerly Candida lipolytica) (2) Yeasts and molds

har-vested from the exponential phase of growth are more sensitive to the activity of these cell

wall digesting enzyme preparations than are late exponential or stationary phase cells

1.3.2 Yeasts

Yeasts can be divided into two metabolic groups: facultative anaerobes and obligate

aer-obes The facultative anaerobes are capable of anaerobic growth and fermentative

as S cerevisiae (Figure 1.1), when grown in the presence of 3 ppm of the DNA

intercol-lating agent acriflavine, can have their mitochondrial DNA selectively mutated so that

mitochondria are eliminated, resulting in obligately fermentative strains unable to utilize

oxygen (3) Such strains produce smaller cells than wild-type strains and result in “petite”

colonies that are notably reduced in size

Baker’s yeast was originally obtained from the brewing industry; the top yeast

S cerevisiae was conveniently skimmed from the top surface of fermentation tanks During

the mid-1800s the brewing industry converted to strains of the bottom-settling yeast

Saccharomyces carlesburgensis, which precipitated the establishment of the baker’s yeast

industry Producing baker’s yeast using sucrose derived from molasses requires vigorous

aeration of the culture medium so that a maximum amount of carbon flows to cell mass

production and not to ethyl alcohol formation Vigorous aeration of S cerevisiae strains in

the presence of an abundant level of carbohydrate (about 3%) results in the metabolic

dominance of fermentation and is known as the crabtree effect (4) This in turn results in a

significant level of ethyl alcohol and a notably reduced level of cell mass The baker’s yeast

industry is able to overcome the crabtree effect using incremental feeding which involves

the pulsed addition of molasses to aerated culture tanks, so that at no time does the residual

level of sucrose rise above 0.0001% Thus there is no feedback repression of mitochondria

formation caused by elevated levels of sucrose In this case, derepressed mutants that do not

exhibit feedback repression are not used The yeast Candida utilis is facultatively anaerobic;

however, under conditions of vigorous aeration and elevated sugar levels the crabtree effect

is not observed Thus, the organism can be conveniently used to convert the lactose in whey

and the sugars in sulfite waste liquor to cell mass for use as food and fodder yeast

All yeasts are capable of utilizing glucose The utilization of other sugars depends

on the species; the spectrum of sugars used constitutes a major criterion for the identity of

yeasts All yeasts are capable of utilizing ammonium sulfate as a sole source of nitrogen

Very few yeasts are capable of utilizing nitrate as a sole nitrogen source Among

asco-spore-producing yeasts, the number (1, 4, or 8) and shape of ascospores (spherical, oval,

kidney, hat, saturn, needle) in asci constitutes an additional major criterion for genus and

species identity Most yeasts divide by budding; however, members of the strongly

fermen-tative yeast genus Schizosaccharomyces divide solely by transverse fission (Figure 1.2).

1.3.3 Molds

In developing mold cultures for the production of food additives, it is important to keep in

mind that all molds are obligate aerobes The maximum production of primary

metabo-lites (e.g., amino acids) and secondary metabometabo-lites (e.g., extraceullular enzymes)

invari-ably occurs with wild-type cultures under the condition of static surface growth This

contrasts with submerged cultivation which invariably involves the use of selected

mutants Molds are classified into four classes The Phycomycetes do not have complete

cross walls in their hyphae and therefore exhibit unidirectional protoplasmic streaming

(coenocytic movement) or flow throughout their hyphae Phycomycetes also possess the

unifying characteristic of producing aerially borne asexual fruiting structures known as

sporangia, with internal sporangiospores borne on a bulblike structure referred to as the

In haploid strains

Growth on acetate agar

Intraascus conjugation

Ascus with

4 ascospores

Growth in high glucose medium

a a

a a

Figure 1.1 Life cycle of Saccharomyces cerevisiae.

Food Microbiology 7

columella (Figure 1.3) Some, but not all, Phycomycetes produce a sexual spore, known

as a zygospore, derived from the fusion of opposite mating types which occurs freely in

culture media (Figure 1.3) Color and the microscopic orientation and appearance of these

structures are used to establish genera and species The class Ascomycetes houses fungi

(both yeasts and molds) that produce the sexual ascospore Molds in this class have

com-plete cross walls in their hyphae and therefore do not exhibit protoplasmic streaming All

ascomycete molds produce characteristic conidiospores, which occur in chains or clusters

The characteristic blue-green coloration of members of the genus Penicillium (Figure 1.4)

is due to the coloration of the long chains of conidiospores borne by all members of this

genus The characteristic coloration (yellow, brown, green) of various species of the genus

Aspergillus (Figure 1.4) is also due to the coloration of the conidiospores The major

cri-teria for the establishment of genus and species of this class are the visual coloration of

the mass of growth in conjunction with the microscopic appearance and three

dimen-sional orientation of the hyphae and conidiospores A major distinction between

ascomy-cete yeasts and molds is derived from the fact that yeasts produce “naked” asci and

frequently contain four and sometimes eight ascospores, depending on the species The

asci of yeasts occur free in the medium, whereas most ascomycete molds produce asci

A

Figure 1.2 Cellular structures and asci of the strongly fermentative yeast genus Schizosaccharomyces

(A) Transverse fission of vegetative cells exhibited by all members of the non-budding genus

Schizosaccharomyces (B) Ascus containing four ascospores representative of Schiz pombe

and Schiz versatilis (C) Swollen and distended ascus of Schiz octosporus containing eight

ascospores.

Zygospore Gametangia

−

+

Suspensor

Columella Sporangial wall Sporangiospores Sporangium

Germination to sporangiophore and terminal sporangium Sporangiophore

Figure 1.3 Asexual and sexual structures of a typical terrestrial member of the class Phycomycetes.

with internal ascospores inside a fruiting structure known as a cleistothecium (completely

closed) or as a perithecium (open at one end) (Figure 1.4) The class Fungi imperfecti

(Figure 1.5), otherwise known as Deuteromycetes, is essentially identical to the

Ascomycetes (hyphal crosswalls are present and conidiospores are produced) except that

the sexual ascospore is not produced The class Basidiomycetes houses molds and

yeast-like organisms that produce the sexual basidiospore; many also produce conidiospores

Other basidiomycetes produce budding yeastlike cells, which can result in confusing such

isolates with true yeasts The commercial use of molds in various food systems usually

involves the harvesting of the asexual sporangiospores or conidiospores for use as

inocu-lum This allows the density of the inoculum to be based on the precise density or number

of spores per unit of volume, which can be readily determined by microscopic count The

use of mycelial mass as an inoculum is more difficult with respect to directly determining

the quantity of the cell mass in the inoculum volume, for obvious physical reasons

1.4 MICROBIAL TAXONOMY

1.4.1 General

After Anton van Leeuwenhoek developed the microscope (circa 1700), Carle Linnaeus

developed the binomial system of nomenclature in which each biological entity is

allo-cated to a genus and species The first letter of the genus designation is always capitalized,

the species is entirely lower cased, and both are in italics, e.g., Penicillium roquefortii,

Schizosaccharomyces octosporus, Saccharomyces cerevisiae, Xanthomonas campestris,

Spherical head of conidiospores

Phialids (sterigmata) Conidiospores

Mature ascus containing

8 ascospores

Figure 1.4 Asexual and sexual structures of fungal members of the class Ascomycetes.

Food Microbiology 9

Lactobacillus acidophilus The concept of a bacterial genus usually encompasses a

well-defined group that is clearly separated from other genera Interestingly, there is no general

of numerous bacterial genera are presently considered to involve a significant level of

subjectivity (5)

Species are frequently divided into subspecies, called varieties, serotypes, or biotypes,

using the abbreviations “var.” or “subsp.”, e.g., Saccharomyces italicus var melibiase,

Escherichia coli subsp communior An organism is occasionally found in the literature under

several names; e.g., Candida utilis, Torula utilis, Torulopsis utilis Only one of the names is

usually correct, the others being synonyms In this case Candida utilis is correct (6) However,

when two organisms can be confused in the text resulting from such contractions, e.g., the

bacterium Escherichia coli (E coli) vs the protozoan Entamoeba coli (E coli), alternate

contractions, solely for the purpose of clarity, are then used, e.g., Esch coli vs Ent coli.

Figure 1.5 Shape and configuration of conidiospores and associated structures of representative

members of the class Fungi imperfecti.

Two celled conidium Conidia

Conidia

Conidiophore

Conidiophore Conidiophore

Microconidium Conidiophore

Sickle shaped multicelled macroconidium

Conidiophore Conidia

Conidiophore

Multicelled conidia

Conidia Conidiophore

Scopulariopsis

Conidiophore Conidium

Rectangular arthrospores (submerged fragmented hyphae)

Oval arthrospores (aerial)

Swollen tips (which bear conidia)

Geotrichum (Oospora)

Cladosporium Trichothecium Fusarium

Cephalosporium Alternaria

Botrytis

Conidiophore Conidia

1.4.2 Classification of Bacteria

Bacteria are now classified into two major groups, the Eubacteria and the Archaebacteria

(which were formerly grouped under the Protista) The majority of bacteria involved with

food systems are Eubacteria The Archaebacteria presently house the unique halobacteria,

which are obligate halophiles and can cause the red tainting of salted fish All bacteria fall

into two convenient groups, those that stain purple with the Gram stain (Gram-positive) and

those that stain red with the Gram stain (Gram-negative) In Gram-positive bacteria, there

is a bi-lipid membrane between the cell wall and cytoplasm, with the cell wall consisting

mainly of peptidoglycan linked with teichoic acids The cell envelope of Gram-negative

bacteria is more complex, consisting of three layers, often referred to collectively as the

sacculus The innermost layer (i.e., the inner cytoplasmic membrane) is adhered to the

linked to elongated lipoprotein molecules This peptidoglycan–lipoprotein complex partly

occupies the periplasmic space between the two (inner and outer) hydrophobic membranes

The outermost layer is an outer membrane consisting of phospholipids, lipopolysaccharides

(LPS), and proteins The LPS content of the sacculus of Gram-negative bacteria constitutes

an impermeable barrier to many polar and nonpolar molecules, including dyes and

surface-active agents such as bile salts This difference in permeability to dyes and surface-surface-active

agents is used in the selective isolation of Gram-negative organisms with the complete

exclusion of Gram-positive organisms, as with the use of MacConkey agar

There are three general metabolic groups of bacteria: (1) obligate aerobes, (2) tative anaerobes, and (3) obligate anaerobes Representative members of each of these

facul-groups are found among both the Gram-positive and Gram-negative bacteria

1.4.3 Serotypes

Serotyping involves the production of antibodies following the injection of a suitable

mam-mal with the microorganism or a specific extract of the organism If an organism is

non-flagellated then serotyping will be based on the somatic antigens If the organism is

flagellated then serotyping may also be based on the flagella antigens Three antigenic sites

are recognized: somatic (O) (German “Ohne”) or body, flagella (H) (German “Hauch”) or

motility, and K (German “Kapsel”), e.g., Escherichia coli O157:H7 The O antigens are

comprised of the O polysaccharides that are on the surface and are heat stabile The K and

H antigens are heat labile With whole bacterial cells, agglutination methods are used With

soluble antigens such as toxins, precipitin or gel diffusion assays are used

1.4.4 Molecular Taxonomy

Each microbial species is presently characterized as having a specific percent molar

%  mols % G
mols % C
mols % T
mols % A Because each guanine nucleotide on

one strand of DNA is hydrogen bonded to a cytosine nucleotide on the opposite strand, and

because each thymidine nucleotide is hydrogen bonded to a cytosine nucleotide on the

opposite strand, the mols % guanine is always equal to the mols % C and the mols %

thymine is always equal to the mols % cytosine By convention, each organism is then

G
C)
(mols% A
T) or mols % GC  100 mols %  (mols % A
T) All strains of

S cerevisiae are defined as having a molar GC content of 39% Any yeast strain that

devi-ates significantly from this value cannot be considered S cerevisiae With unknown

iso-lates, the value of the molar GC content is primarily exclusionary An unknown organism

with a molar GC content of 50% is clearly not S cerevisiae An unknown isolate with a

molar GC content of 39% may be S cerevisiae, but a molar GC content of 39% is not

conclusive evidence of identity Because all biological species fall within the range of

about 10% to 90% GC, numerous unrelated species have the same numerical value for

their molar GC DNA content For example, micrococci and all mammals and fish have a

molar GC content of 45%

The practical definition of a species is that it consists of a collection of strains that share many features in common and that differ considerably from other strains (5) A spe-

cies is presently defined as encompassing strains with approximately 70% or greater

DNA–DNA similarity based on DNA strand hybridization, and with 5% or less Tm

(Thermal denaturation temperature) for the hybridized strands (8) Phenotypic

character-istics should agree with this definition This corresponds to a 16S ribosomal ribonucleic

acid (rRNA) similarity of 98% or higher (9) The nucleotide sequences of rRNA are far

more conserved than DNA among various taxonomic groups rRNA is capable of

hybrid-izing with DNA; however, RNA–DNA hybridization is far less discriminating in terms of

recognizing differences between strains of the same species It is, however, of utility in

discerning the difference between two different species of the same genus Stated more

succinctly, DNA–DNA hybridization experiments are used to detect similarities between

closely related organisms, whereas RNA–DNA hybridization experiments are used to

detect similarities between more distantly related organisms (10) rRNA sequence data is

considered more appropriate for determining inter- and intrageneric relationships than for

confirming the species identity of an isolate (11) Several groups of organisms have been

found to share almost identical 16S rRNA sequences but a DNA–DNA hybridization

sig-nificantly lower than 70%, indicating that they represent different species (12)

The early classification of microorganisms was based on the utility of their tion and identification What emerged with bacteria, however, was a dual system of clas-

recogni-sification, one based on metabolism and the other on morphology, which are still with us

In 1910, Orla-Jensen proposed that all lactic-acid-producing bacteria (cocci and rods) be

housed in the family Lactobacteriacea In contrast, the family Micrococcaceae houses the

various genera of spherical cells or cocci The bacterial phylogeny that has emerged from

molecular sequence data has little in common with these early concepts regarding the

morphological relationships of microbial groups (13) Morphology is no longer the

guid-ing principle regardguid-ing phylogenetic relationships, in that most characteristics of bacterial

morphology are presently regarded as too simple not to have evolved independently in

unrelated organisms (13) However, the concept of morphology as a utilitarian character of

an organism can be of great value, if, for example, one suspects that a pure culture of a

coccus is contaminated and finds rods present

1.5 METABOLIC CONTROL FOR ENHANCED METABOLITE

PRODUCTION

A number of microbial processes in the production of various food additives involve

limiting one or more critical nutrients The submerged production of citric acid by

A niger involves limiting both iron and phosphate to achieve maximum yields (14) The

production and excretion of maximum amounts of glutamic acid by Corynebacterium

glutamicum is dependent on cell permeability Increased permeability can be achieved

through biotin deficiency, through oleic acid deficiency in oleic acid auxotrophs, through

the addition of saturated fatty acids or penicillin, or by glycerol deficiency in glycerol

auxotrophs (15)