Phylogenetic Constitution and Survival of Microbial Biofilms Formed on the Surface of Polyethylene Composites Protected with Polyguanidine Biocides

Round 1

Reviewer 1 Report

The manuscript describes multispecies microbial communities that were isolated from the surface of polyethylene samples either incubated or found in the environment, and their taxonomic composition when they grew on polyethylene composites with different derivates of guanidine. The manuscript s really well-written and is moderately innovative. I just have some minor comments to suggest before publication.

In the Introduction section, I miss some lines about all the uses of polyethylene in devices or equipment that use to be exposed outdoors or in contact with soil or environmental waters. Please, add this information to highlight the importance of your work.

In the Introduction section, please, use the full name of “ESKAPE microorganisms”. The reader of this journal may not be familiar with this term.

In line 320, the authors assert that “communities are presented in Table 2.”. Table 2 shows no communities. May this Table be missing?

In line 526, there is a typo. Correct “As” with “as”.

In the Discussion section, in lines 538-543, I kindly disagree with the authors, I consider that their experiments are reflecting the PHMG effect on the planktonic state of those bacteria which would be responsible for forming the biofilm of the polyethylene. Regarding this, I wonder if the PMHG effect on planktonic bacteria has already been described in the literature. If so, please, add those references. If not, the author should do it.

Throughout the manuscript, please, remove all references linked to any clinically potential use of polyethylene. Considering the origin of the samples used to isolate the different strains used in this study, the only uses that can be claimed are environmental. Bacterial species linked to polyethylene-related infections use to be human-related staphylococci.

 Light editing of the English language is required.

Author Response

Dear  Reviewer,

thank you for your comments, you give us the opportunity to present our work  in the most favorable light. All changes after your comment marked green color.

In the Introduction section, I miss some lines about all the uses of polyethylene in devices or equipment that use to be exposed outdoors or in contact with soil or environmental waters. Please, add this information to highlight the importance of your work.

Fixed

In the Introduction section, please, use the full name of “ESKAPE microorganisms”. The reader of this journal may not be familiar with this term.

Done

In line 320, the authors assert that “communities are presented in Table 2.”. Table 2 shows no communities. May this Table be missing?

The table is not lost, it contains the characteristics of communities No. 1-10. The caption in manuscript and heading of the column have been changed.

In line 526, there is a typo. Correct “As” with “as”.

Fixed

In the Discussion section, in lines 538-543, I kindly disagree with the authors, I consider that their experiments are reflecting the PHMG effect on the planktonic state of those bacteria which would be responsible for forming the biofilm of the polyethylene. Regarding this, I wonder if the PMHG effect on planktonic bacteria has already been described in the literature. If so, please, add those references. If not, the author should do it.

PHMG-GC is one of the main water disinfection agents now. The effectiveness of PHMG-GC was not in doubt, we used it in our previous work (https://knepublishing.com/index.php/KnE-Life/article/view/10155) as a positive control. There are a number of another works about its action:
https://pubmed.ncbi.nlm.nih.gov/24888899/
https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.2008/003350-0
   This work was devoted not to PHMG-GC, but to its derivatives synthesized at the Topchiev Institute. Therefore, although we mention PHMG-GC as the most well-studied derivative, a detailed description of its own task is still not included in our work.

Throughout the manuscript, please, remove all references linked to any clinically potential use of polyethylene. Considering the origin of the samples used to isolate the different strains used in this study, the only uses that can be claimed are environmental. Bacterial species linked to polyethylene-related infections use to be human-related staphylococci.

 

We would prefer to stay links to medical issue, because the mechanisms of biofilm formation are universal, regardless of the source of fouling cells, whether it is sewage or nosocomial infections. Naturally, our work cannot be directly applied to the medical field, and it is impossible to recommend these materials for use in the clinic only on the basis of this work. I would like to draw the attention of other researchers to the possibility of creating composites based on PE and PHMG derivatives, the original methodological solution for which was proposed by our authors from the Topchiev Institute (creation of MTT + PHMG + PE composites). Such materials are not used in the clinic (at least, I could not find such works). I cannot share the opinion of a respected reviewer that only microorganisms related to staphylococci are significant for medicine in the context of biofilms on the PE surface, although Staphylococcus is certainly one of the most important genus in this issue.

The results obtained by us are importance for medicine, since they can be dangerous for preventing infection in the field of medicine. For example, the Gram-negative bacterium (Pseudomonas aeruginosa) and the Yarrowia (Candida) ascomycete that we are studying cause infectious processes in humans during fouling of hemodialysis devices (hemodialyzers), venous and urinary catheters (central venous catheters, urinary catheters), dental prostheses (dental prosthetics), contact lenses (Contact lenses) and other garments (link 2: Li, X., Sun, L., Zhang, P., Wang, Y. Novel Approaches to Combat Medical Device-Associated BioFilms. Coatings 2021, 11, 294. https://doi.org/10.3390/coatings11030294). In addition, the gram-positive bacterium Kocuria rhizophila that we studied is not only a conditional human pathogen, but can cause severe bacteremia in cardiac catheter fouling (Pierron, A., Zayet, S., Toko, L., Royer, P., Garnier, P., & Gendrin, V.. Catheter-related bacteremia with endocarditis caused by Kocuria rhizophila. Médecine et Maladies Infectieuses. 2020. doi:10.1016/j.medmal.2020.09.007). Polyguanidine-based biocides incorporated into medical devices, in particular wound dressing materials (wound dressing impregnation) prevent wound infections (Zhang, J., Hu, L., Zhang, Q. et al. Polyhexamethylene guanidine hydrochloride modified sodium alginate nonwoven with potent antibacterial and hemostatic properties for infected full-thickness wound healing. Int J Biol Macromol 2022, 209, 2142-2150. https://doi.org/10.1016/j.ijbiomac.2022.04.194;

Gerasin, V.A., Mendeleev, D.I., Kurenkov, V.V. et al. Guanidine-Containing Organomineral Complexes as Biocide Additives to Polymeric Composites. Russ J Appl Chem 2018, 91, 1297–1304. https://doi.org/10.1134/S1070427218080074 )

I will add these references to the manuscript if the esteemed reviewer deems it necessary to justify mentioning the possibility of applications of our work in further medical developments.

Light editing of the English language is required.

Unfortunately, authors are not native in English. The manuscript had undergone English language editing by MDPI, certificate attached to this download.

Sincerely, authors

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript entitled on “Phylogenetic Constitution and Survival of Microbial Biofilms  Formed on the Surface of Polyethylene Composites Protected  with Polyguanidine Biocides” has been done by Authors.

Overall the research is good. All the figures and tables are adequate. This paper is of interest, but few important corrections are needed to improve the manuscript quality.

1.      Language editing is essential.

2.      Reframe the keywords

3.      Highlight the novelty in abstract.

4.      Ensure all the microbes name should be italics.

5.      Figures 6- 8 are not clear.

6.      Conclusion should be explain clearly

7.      Provide clear SEM images and highlight your finding in SEM images.

8.      What is outcome of the present investigation and its advantage? Add in introduction

1.      Language editing is essential.

Author Response

Dear  Reviewer, 
thank you for your comments, you give us the opportunity to present our work  in the most favorable light. All changes after your comment marked red color.

1. Language editing is essential.  Unfortunately, authors are not native in English. The manuscript had undergone English language editing by MDPI, certificate attached to this download.
2. Reframe the keywords. Keywords changed.
3. Highlight the novelty in abstract. Abstract changed.
4. Ensure all the microbes name should be italics. We tried fixed all microbes name.
5. Figures 6-8 are not clear. Figures 6-8 show Krona diagrams reflecting the diversity of strains in the composition of communities after a number of passages. To the authors' knowledge, this is the generally accepted way of presenting the results of an NGS study. The authors would be grateful if a respected reviewer would suggest a more appropriate way to present the results of an NGS study or how to make these diagrams more clear.
6. Conclusion should be explain clearly. Conclusion changed.
7. Provide clear SEM images and highlight your finding in SEM images. Figure 13 changed.
8.   What is outcome of the present investigation and its advantage? Add in introduction. The introduction contains a statement of the problem and a brief description of our previous work. The result of the work is briefly described in the conclusions, and more fully - in the manuscript.

Sincerely, authors

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

 

Your article is very interesting and applicable. It is well organized in suitable sections. The abstract is well written.

The introduction section needs an improvement in terms of more references in order to support some statements there. Please see an attached version of the manuscript with suggestions.

The Experimental section is very good. Results and Discussion parts slo provide extensive explanation and there are no particular comments from my side. They are understandable for readers and contain the most important data observed through this study.

Well done.

 

Thank you.

Comments for author File: Comments.pdf

The English in this manuscript is very well, it is understandable and I do not think that it needs extensive editing.

Author Response

Dear  Reviewer, 
thank you for your comments, you give us the opportunity to present our work  in the most favorable light. All changes after your comment marked yellow color.

I can't agree with just one edit, "based from" isn't better than "based on". All other edits have been added to the manuscript.

Sincerely, authors

Round 2

Reviewer 2 Report

All the corrections have been carried out by authors. The manuscript looks good.