Persistence comparison of two Shiga-toxin producing Escherichia coli (STEC) serovars during long-term storage and thermal inactivation in various wheat flours

Ian S. Hines; Tom Jurkiw; Emily Nguyen; Martine Ferguson; Sultana Solaiman; Elizabeth Reed; Maria Hoffmann; Jie Zheng

doi:10.1371/journal.pone.0299922

Peer Review History

Original SubmissionOctober 5, 2023
2 Jan 2024 Decision Letter - Arun K. Bhunia, Editor PONE-D-23-32459Persistence comparison of two Shiga-toxin producing Escherichia coli (STEC) serovars during long-term storage and thermal inactivation in various wheat floursPLOS ONE Dear Dr. Zheng, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. ============================== Use appropriate controls to demonstrate the temperature effect on E. coli without the flour ============================== Please submit your revised manuscript by Feb 16 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. 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The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. Additional Editor Comments: Two reviewers rendered a mixed decision. One was favorable, while the second reviewer questioned the experimental design, especially the missing controls. Given such diverse opinions, the manuscript cannot be considered for publication. However, if the authors are willing to revise the manuscript as suggested, the manuscript could receive further consideration. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: No ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: Thank you for the nice work done. The manuscript is very well written. While I do not see much novelty compared to what we already knew about the topic, some of the side information as well as additional data presented adding up to the field convinced me that having it published is better than not! Reviewer #2: In the present study titled “Persistence comparison of two Shiga-toxin producing Escherichia coli (STEC) serovars during long-term storage and thermal inactivation in various wheat flours” researchers tried to investigate the impact of different flour types on the persistence of STEC during desiccation and thermal inactivation. They have used two serovars of STEC, O121 and O157, to inoculate each of five different types of common wheat flours: whole wheat, bleached, unbleached, bread, and self-rising. They have examined for the stability of STEC during storage up to 42 days under isothermal conditions at 60, 70, 80, and 90oC. These researchers found that STEC storage persistence was generally not affected by flour type, however, two different strains survived differently, O121 survived significantly better than O157 for both conditioning and storage periods. However, without using appropriate controls in this study, it seems difficult to draw any conclusion. Major comments: 1. For the effect of isothermal temperatures on both serovars of STEC (Fig 3 and Fig 4), researchers didn’t use appropriate controls. They should use an “only temperature control”, bacteria growing in water/PBS without any flour type to check if the effects observed were due to change in only temperature parameter. Then, the effect of temperature on serovars can be subtracted from the observed effects of temperatures on serovars in the different flour types. Without this control it is irrelevant to draw any conclusion. 2. Quality and labelling of figures are very poor. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: Yes: Fereidoun Forghani Reviewer #2: Yes: Shivendra Tenguria ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0299922.r001
Revision 1
12 Feb 2024 Author Response Reviewer #1: Thank you for the nice work done. The manuscript is very well written. While I do not see much novelty compared to what we already knew about the topic, some of the side information as well as additional data presented adding up to the field convinced me that having it published is better than not! Response: We thank the reviewer for this very supportive comment! Reviewer #2: In the present study titled “Persistence comparison of two Shiga-toxin producing Escherichia coli (STEC) serovars during long-term storage and thermal inactivation in various wheat flours” researchers tried to investigate the impact of different flour types on the persistence of STEC during desiccation and thermal inactivation. They have used two serovars of STEC, O121 and O157, to inoculate each of five different types of common wheat flours: whole wheat, bleached, unbleached, bread, and self-rising. They have examined for the stability of STEC during storage up to 42 days under isothermal conditions at 60, 70, 80, and 90oC. These researchers found that STEC storage persistence was generally not affected by flour type, however, two different strains survived differently, O121 survived significantly better than O157 for both conditioning and storage periods. However, without using appropriate controls in this study, it seems difficult to draw any conclusion. Response: We appreciate the reviewer's comment. As highlighted by the reviewer, our objective is to incorporate new information regarding the influence of various flour types on the persistence of STEC during storage at RT and following thermal inactivation. In our analyses, we employed time “0” at storage temperature (i.e., RT) to assess STEC persistence in flour during storage or time “0” right before thermal treatment as controls to investigate STEC survival in flour during thermal inactivation. In the Bayesian first-order isothermal inactivation model we used in the study, D-value was calculated for each serovar at each isothermal temperature. Comparison of D-values between the serotypes was carried out under the same isothermal temperature for the same type of wheat flour. No statistical difference was found in the thermal resistance curves between the two serovars at each isothermal temperature. We believe we have implemented appropriate controls to derive meaningful conclusions. Major comments: 1. For the effect of isothermal temperatures on both serovars of STEC (Fig 3 and Fig 4), researchers didn’t use appropriate controls. They should use an “only temperature control”, bacteria growing in water/PBS without any flour type to check if the effects observed were due to change in only temperature parameter. Then, the effect of temperature on serovars can be subtracted from the observed effects of temperatures on serovars in the different flour types. Without this control it is irrelevant to draw any conclusion. Response: We thank the reviewer for the comment. In the investigation of thermal inactivation, as illustrated in Fig 3 and Fig 4, we have concluded that there is no significant impact of flour type on STEC survival under thermal inactivation, and there is no significant difference in survival between the serovars under the same temperature within the same flours. We employed time "0" in flour right before thermal treatment as a control, which is appropriate for this study, as the curves were log reductions relative to the 0-minute timepoint. As we compared the survival rate (D-value) of different serovars under the same thermal condition within the same flour, temperature is not a variable in the comparison. In addition, we tested the effects of different isothermal temperatures on the two serovars within only PBS as the reviewer suggested. Similar for both O157 and O121, after the initial 6-7 log reduction, no enumerable culture was recovered by the second timepoint for each isothermal temperature, indicating that the thermal treatment is very effective in killing pathogens without the protection of the food matrix. Since the goal of this study was to investigate the difference in survival of STEC serovars in multiple flour types, we believe that the more appropriate control is the time “0” sampling point. We apologize for any confusion and have adjusted the text to enhance the clarity. 2. Quality and labelling of figures are very poor. Response: Each figure has been updated with a higher resolution, larger font size, and larger lines/dots within the plot. All manuscript figures have also been modified by PACE. Attachments Attachment Submitted filename: Response to Reviewers_final.docx https://doi.org/10.1371/journal.pone.0299922.r002
19 Feb 2024 Decision Letter - Arun K. Bhunia, Editor Persistence comparison of two Shiga-toxin producing Escherichia coli (STEC) serovars during long-term storage and thermal inactivation in various wheat flours PONE-D-23-32459R1 Dear Dr. Zheng, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Arun K. Bhunia, Ph.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Thank you for addressing all the concerns raised by the reviewers. The article meets the journal standards for publication. Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #2: (No Response) ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #2: Response: The authors have addressed all of my review comments. ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #2: No ******** https://doi.org/10.1371/journal.pone.0299922.r003
Formally Accepted
29 Feb 2024 Acceptance Letter - Arun K. Bhunia, Editor PONE-D-23-32459R1 PLOS ONE Dear Dr. Zheng, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Arun K. Bhunia Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0299922.r004

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