FATE OF FOODBORNE BACTERIA IN PESTICIDE FORMULATIONS A Thesis Submitted to the Faculty of Graduate Studies The University of Manitoba by Tat Yee Guan In Partial Fulfillment of the Requirements for the Degree of Master of Science Food Science Department May 2000 tr¡$onat t-iorav nationare t*t åfåiffil:" Acquisitions and Acquisitions et Bibiiographicservices servicesbibliographiques 395 Wellington Street 395, rue Wellington Ottawa OÑ K1A oN4 ottawa ON K1A oN4 Canada Canada Yout l¡\e Volrc ñfércnce Our l¡le Notrc élércnce The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic fonnats. la forme de microfiche/fiIm, de reproduction sur papier ou sur format électronique. 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Neither the droit d'auteur qui protège cette thèse. thesis nor substantial exfracts frorn it Ni la thèse ni des exfiaits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son perrnission. autorisation. 0-612-51719-5 Canadä THE I]NÑTRSITY OF MANITOBA FACULTY OF GRADUATE STIIDIES ***** C OPYRIGHT PERMISSION PAGE Fate of Foodborne Bacteria in Pesticide Formulations BY Tat Yee Guan A Thesis/Practicum submiffed to the Faculty of Graduate Studies of The Universify of Manitoba in partial fulfillment of the requirements of the degree of Master of Science TAT YEE GUAN O 2OOO Permission has been granted to the Library of The University of Manitoba to lend or sell copies of this thesis/practicum, to the National Library of Canada to microfilm this thesis/practicum and to lend or sell copies of the fiIm, and to Dissertations Abstracts International to publish an abstract of this thesis/practicum. The author reserves other publication rights, and neither this thesis/practicum nor extensive extracts from it may be printed or otherwise reproduced without the author's written permission. iii I hereby declare that I am the sole author ofthis thesis. I authorize the University of Manitoba to lend this thesis to other institutions or individuals for the purpose of scholarly research. Tat Yee Guan I further authorize the University of Manitoba to reproduce this thesis by photocopying or by other means, in total or in part, at the request of other institutions or individuals for the purpose of scholarly research. Tat Yee Guan DEDTCATION To the memory of my grandmother, who has played an influential role in shaping my life, whose beautiful soul and gentle kindness will live in my memory and heart forever. vl ACKNOWI-EDGEMENTS First I would like to thank both my advisors, Dr' G' Blank, for his guidance H' during the entire research and assistance in the completion of this thesis, and Dr' A' studies' I Ismond, for her patience and on-going concern for my progress in the graduate my would also like to extend a thank you to Dr. R. Van Acker for his participation in examining committee. Appreciation is extended to the University of Manitoba Bursary Programs which provided me with financial support. There are many people in the Department of Food Science whom I would also like to thank. Jim Rogers for his technical support in computers, Randy Roller for his Sapirstein for assistance in statistical analysis, Dr. Holley for his expertise and advise, Dr' part-time analyst his expertise in statistical analysis, Arnie Hydamaka for hiring me as a which provided me financial support, Dr. A¡ntfreld for her genuine encouragement and and concern, Georgina Mejia, Aniko Bernatsky, and Amanda Penzick for their friendship laughter. Thank you all for being there for me' A heartfelt thanks to my family, Kim Pong Guan, Lee Fong Liew, Tat Jiin Guan, Dennis Guan, and Jonathan Guan. Thank you for your unending love, support, and my encouragement from the very beginning of my masters studies. Thank you to pursuing brothers and sister, who have been taking good care of the family while I was this path. Thank you to my best friend, Kevin Koo, who has been really supportive and would caring at times of difficulty and discouragement. Last but certainly not the least, I like to thank God for so many blessings. Thank you for Your grace' which is always sufficient for me. vlr TAtsT.E OF'CTI\TÐI\TS ACKNOWLEDGEMENTS """"""""""'vi TABLE OF CONTENTS """'vii ix LIST OF T48L8S............ """' LIST OF FIGUR8S............ """""""""""'x xi LIST OF APPENDICES """"' 48STR4CT.............. """"""'xiii TNTRODUCTTON """""""""" 1 LITERATURE REVTEW ............ """"""'4 1. Minimally Processed Refrigerated Fruits and vegetables..........'. """4 "'7 2. Pathogenic Bacteria Associated with Fruits and Vegetables """""" """ " "" i. Escherichia coli O157"H7 ' ' ""'7 """7 a. Characteristics I b. Outbreaks associated with fruits and vegetables ' 10 c. Growth and survival in fruits and vegetables """"" """"""""' i3 ä. Salmonelta spp....... """""""""" 13 a. Characteristics ""' associated with fruits and vegetables ""'T4 b. Outbreaks i6 c. Growth and survival in fruits and vegetables """""" """""""' 18 i\i. Listeria monocytogenes '.""""' """"""""" 18 a. Characteristics ""' 19 b. Outbreaks associated with fruits and vegetables c. Growth and survival in fruits and vegetables """""" """""""'21 iv. Shigetla spp ... .-- """""""""'23 23 a. Characteristics """"" b. Outbreaks associated with fruits and vegetables ""'24 c. Growth and survival in fruits and vegetãbles """""" """""""'26 1. Vectors for Transmission of Pathogens to Fruits and Vegetables""""""' """""'27 i. Use of contaminated manur. or r"*uge sludge as fertilizer """""'29 33 ii. Use of reclaimed or polluted water foi irrigation"""""""' """""" 35 2. Pesticides. 35 Types i. an5t ii. Application methods............'.. 41 iii. Microbial degradation.........'.. vlll MATERIALS AND METHODS .............. """""""'46 1. Cultures, Growth Conditions, and Inocula Standardization.".... ------...46 2. Pesticides. """"""""""'47 3. Short Time Surviva1............ """""'47 4. Growth Response in Pesticide Solutions "" 50 5. Pesticide Minimum Inhibitory Concentration (MIC) """' 51 6. Statistical Analvsis.... ' ' "' 51 RESULTS .'' 53 .... '. ' 53 1 . Short Time survival of Pathogens in Pesticide Solutions.. i. Escherichia coli Ol57.H7 ...""...... ' 53 ii Salmonella spp.... .. " ""' 58 iii Shigetla tPP. ' 61 iv. Listeria monocytogenes .--........ " """"'64 Z. pesticide Minimum Inhibitory Concentrations relativeto E. coli OI5l -H7 3. Time-Course Growth Patterns in Pesticide Solutions' """'69 Escherichia coli OI57.H7 """"'69 Salmonella typhimurium.............. """"72 Shigetla soniei """'15 Listeria monocytogenes........... ' ""'78 4. Effect of Incubation Temperature on Growth of E. coli O15l.H7 in Pesticide Solutions 81 5. Effect of Pesticide Concentration on Growth of E. coli OI57 .H7 in Pesticide Solutions 83 6. pH of Pesticide Solutions .......'....... ". 83 DISCUSSION 85 CONCLUSIONS 96 RECOMMENDATIONS FOR FUTURE STUDIES .... .......' 98 REFERENCES 99 APPENDICES ......... 137 ix I,[ST' TF' TAtsI.ES and Table 1. Sources of pathogenic microorganisms on fruits and vegetables conditions ihat influence their survival and growth """"""'28 Table2. Pesticide classes and uses ' " 36 38 Table 3. Common formulations of pesticides ...-....... """"' Table 4. Fifteen pesticide products investigated in this research, their common spray diiutions, and the pH values of the pesticide solutions .. ...... 48 Table 5. Survival of Escherichia coli OI51 strain 7236 (human isolate) in pesticide solutions after contact times of I and 24 hours at22"C -...........54 Table 6. Survival of Escherichia coli Ol57 strain 7283 (ground beef isolate) in pesticide solutions after contact times of 1 and 24 hours at 22"C ..... 55 TableT. Survival of Escherichia coli OI57 strain 7Il4 (bovine isolate) in pesticide solutions after contact times of 1 and 24 hours at 22oC ..... 56 Table 8. survival of salmonella typhimurium in pesticide solutions after contact times of 1 and 24 hours atL2oC...... "' 59 Table 9. Survival of Salmonellø enteritidis in pesticide solutions after contact times of 1 and 24 hours at22"C. See appendix table 5 """""""' ' " 60 Table 10. Survival of Shigetla sonnei in pesticide solutions after contact times ofl and 24 hours at22"C ' ""'62 Table 11. Survival of Shigelløflexneri in pesticide solutions after contact times of 1 and 24 hours at22"C """' ' 63 Table 12. Survival of Listeria monocytogeizes strain T9Il2 (human isolate) in pesticide solutions after contact times of I and 24 hours at22"C ...65 Table 13. Survival of Listeria monocytogenes strain 19117 (sheep isolate) in nesticide solutions after contacttimes of 1 and 24 hours at22"C....-..-..--66 Table 14. Minimum inhibitory concentration (MIC) range of pesticide solutions against E. coli OI57:Hl strain 7236 (human isolate) 68 LNST OF FIGUR.ES processed refrigerated Figure 1 A flow diagram for the production of minimally fruits and vegetables """""" ) Figure 2 Mechanisms by which fresh fruits and vegetables can become contaminated with pathogenic microorganisms and serve as vehicles of human ãiteat.s " ' " '30 isolate) Figure 3. Growth of Escherichia coli ol57.H7 strain 7236 (human in pesticide solutions at22oC using a high inoculum. See appendix 10 ..70 Figure 4. Growth of Escherichia coli Ol57.H] strain