{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/115962"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/115962","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Aggregative swab sampling method for romaine lettuce show similar quality indicators and microbial profiles compared to composite tissue samples in a pilot study","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_has_math":false,"creators":["Gathman, Rachel Jade"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Food Science & Human Nutrition","degree_department":null,"school":null,"contributors":["Stasiewicz, Matthew J","Miller, Michael J","Feng, Hao"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-08","date_published":"2022-08","updated_at":"2026-07-22T22:24:55Z","subjects":["preharvest produce safety","leafy greens","microbial community","food safety sampling"],"languages":["en","eng"],"rights":["Copyright 2022 Rachel Gathman"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/115962","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Stasiewicz, Matthew J","Miller, Michael J","Feng, Hao"]},{"key":"dc:creator","label":"Author","values":["Gathman, Rachel Jade"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-08","2022-07-22"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Food Science & Human Nutrition"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["preharvest produce safety","leafy greens","microbial community","food safety sampling"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2022 Rachel Gathman"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/115962"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Rachel Gathman, accepted the attached license on 2022-07-21 at 15:37.","The student, Rachel Gathman, submitted this Thesis for approval on 2022-07-21 at 15:44.","This Thesis was approved for publication on 2022-07-22 at 08:40.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18418 on 2022-11-16 at 10:56:43","The practice of collecting preharvest leafy greens composite tissue samples produces few positive pathogen results. Aggregative sampling is potentially more representative. The purpose of this pilot study was to determine aggregative swabs’ ability to pick up quality indicators, to detect Escherichia coli, and determine if microbial profiles of swabs and tissues were similar. Aggregative swabs (n=12) and composite tissues (n=14) were collected from a one-acre commercial romaine lettuce field in Salinas, CA. Some field portions were inoculated with a rifampicin resistant E. coli cocktail. Aerobic plate counts (APC), coliform counts, and generic E. coli presence were determined using culture-based methods. Further identification of bacteria, their abundances, and microbial diversity of the samples were determined from microbial community profiling using full-length 16S rRNA sequencing. Recovery of APCs were 9.17±0.43 and 9.21±0.42 log(CFU/g) for tissues and swabs, respectively. Means and variance differences between sample types were insignificant (p=0.38 and p=0.92, respectively). Coliform recoveries were 3.80±0.76 and 4.19±1.15 log(CFU/g) for tissues and swabs, respectively. Means and variance differences between sample types were insignificant (p=0.30 and p=0.16, respectively). Presence of generic E. coli showed that swabs could detect E. coli more often than tissues with 8/12 swabs detecting E. coli compared to 3/14 tissues. Microbial profiling revealed that swabs and tissues have similar alpha diversities (p=0.75) and the most prevalent bacterial taxa in similar abundances. These data suggest aggregative swabs perform similar, if not better, than tissue samples in recovering quality and food safety indicators."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Aggregative swab sampling method for romaine lettuce show similar quality indicators and microbial profiles compared to composite tissue samples in a pilot study"]}]}],"canonical_facts":{"dc:contributor":["Stasiewicz, Matthew J","Miller, Michael J","Feng, Hao"],"dc:creator":["Gathman, Rachel Jade"],"dc:date":["2022-08","2022-07-22"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Rachel Gathman, accepted the attached license on 2022-07-21 at 15:37.","The student, Rachel Gathman, submitted this Thesis for approval on 2022-07-21 at 15:44.","This Thesis was approved for publication on 2022-07-22 at 08:40.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18418 on 2022-11-16 at 10:56:43","The practice of collecting preharvest leafy greens composite tissue samples produces few positive pathogen results. Aggregative sampling is potentially more representative. The purpose of this pilot study was to determine aggregative swabs’ ability to pick up quality indicators, to detect Escherichia coli, and determine if microbial profiles of swabs and tissues were similar. Aggregative swabs (n=12) and composite tissues (n=14) were collected from a one-acre commercial romaine lettuce field in Salinas, CA. Some field portions were inoculated with a rifampicin resistant E. coli cocktail. Aerobic plate counts (APC), coliform counts, and generic E. coli presence were determined using culture-based methods. Further identification of bacteria, their abundances, and microbial diversity of the samples were determined from microbial community profiling using full-length 16S rRNA sequencing. Recovery of APCs were 9.17±0.43 and 9.21±0.42 log(CFU/g) for tissues and swabs, respectively. Means and variance differences between sample types were insignificant (p=0.38 and p=0.92, respectively). Coliform recoveries were 3.80±0.76 and 4.19±1.15 log(CFU/g) for tissues and swabs, respectively. Means and variance differences between sample types were insignificant (p=0.30 and p=0.16, respectively). Presence of generic E. coli showed that swabs could detect E. coli more often than tissues with 8/12 swabs detecting E. coli compared to 3/14 tissues. Microbial profiling revealed that swabs and tissues have similar alpha diversities (p=0.75) and the most prevalent bacterial taxa in similar abundances. These data suggest aggregative swabs perform similar, if not better, than tissue samples in recovering quality and food safety indicators."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/115962"],"dc:language":["en","eng"],"dc:rights":["Copyright 2022 Rachel Gathman"],"dc:subject":["preharvest produce safety","leafy greens","microbial community","food safety sampling"],"dc:title":["Aggregative swab sampling method for romaine lettuce show similar quality indicators and microbial profiles compared to composite tissue samples in a pilot study"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Food Science & Human Nutrition"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:55Z"}