Bacterial Biodegradation of Perfluorooctanoic Acid (PFOA) and Perfluorosulfonic Acid (PFOS) Using Pure Pseudomonas Strains

Round 1

Reviewer 1 Report

Regarding the manuscript entitled “Bacterial biodegradation of perfluorooctanoic acid (PFOA) and perfluorosulfonic acid (PFOS) using pure pseudomonas strains” which aimed to biodegradation of perfluorooctanoate (PFOA) and perfluorosulfonic acid (PFOS) using pure individual bacterial strains. The research topic is interested and suitable for sustainability practice to degrade pollutants and keep the environmental safety.  The results indicated that Pseudomonas aeruginosa was able to transform 27.9% of PFOA and 47.3% of PFOS in 96h, while Pseudomonas putida managed to transform 19.0% of PFOA and 46.9% of PFOS in the same time frame. The finding is valuable and will enhance future research in this area. The whole manuscript is well designed and organized in proper way. I advise for acceptance after minor revision as follow:

1-     Figure 3 and 4 including unclear test which should be improved and the figures should be provided with high resolution.

2-     Conclusion is too long and just summarizing the results. It should be restructured and focused on the main finding and how this will encourage future research in the field.

Author Response

Thank you very much for your time and for your comments on our manuscript!

The responces of your comments are listed below and the appropriate modifications were made in the revised version of the manuscript.

Q1: Figure 3 and 4 including unclear test which should be improved and the figures should be provided with high resolution.

A2: Both figures were modified accordingly

Q2: Conclusion is too long and just summarizing the results. It should be restructured and focused on the main finding and how this will encourage future research in the field.

A: The conclusion section was modified accordingly

 

Reviewer 2 Report

Reviewer comments for sustainability-2584871

I assessed the submitted manuscript carefully on ‘Bacterial biodegradation of perfluorooctanoic acid (PFOA) and
perfluorosulfonic acid (PFOS) using pure pseudomonas strains’ by Florentina Laura Chiriac et . al. found interesting, but it requires some major revisions. The list of observations is shown as following points:

----There are numerous typographical errors within the manuscripts.

--LCMS/HRMS or other spectroscopy data may be included to understand the identified fragments as chemical constituents during the biodegradation process.

--The specific mechanism may be explored, how the degradation happened by the bacterial strain in the presence of used key substrates.

--The authors should go away for a careful proofread to remove (a) grammatical errors; (b) many typos; and also (c) remove pointless information and description.

 

--In my opinion, this work might be interesting based on claimed degradation, but the major revision is required to meet the scope of this journal.

 

Author Response

We would like to thank the reviewer for the attention with which he went through our manuscript and for the comments made. I hope that I have made all the necessary changes according to his requirements. See the point by point answers below.

Q1: There are numerous typographical errors within the manuscripts.

A1: The text was reread and corrected for typographical errors

Q2: LCMS/HRMS or other spectroscopy data may be included to understand the identified fragments as chemical constituents during the biodegradation process.

A2: The identification of degradation products was carried out by the quantitative method. Through the qualitative method, no peaks other than those corresponding to the parent compounds could be observed. The explanation, which can be found also in the manuscript, is that the SCAN method is not sensitive enough to identify low concentrations of chemical compounds (fragments). Thus, the possible biodegradation pathways were based only on the quantitative method, using calibration curves for biodegradation products known from the literature.

Q3: The specific mechanism may be explored, how the degradation happened by the bacterial strain in the presence of used key substrates.

A3: In the discussion section, the paragraph which refers to the biodegradation mechanism was improved: ‘The present work showed no abiotic PFOA and PFOS degradation during 96h and subsequently no degradation by-products. In the presence of bacterial strains, there was observed a decrease in PFOA and PFOS concentrations which was correlated to a raise of biodegradation by-product such as PFPeA, PFHxA and PFHpA. Singh and his collaborators proposed a PFOA and PFOS defluorination to be transformed into PFHxA and PFHpA [33]. This transformation fitted our experimental model only when bacterial strains were added, which meant that bacteria could trigger defluorination and C−C bond oxi-dation [8]. The exact bacterial enzymatic equipment involved in PFOA and PFOS bio-degradation and subsequently to defluorination is not yet characterized and make the main theme of a further study.’

Q4: The authors should go away for a careful proofread to remove (a) grammatical errors; (b) many typos; and also (c) remove pointless information and description.

A4: The manuscript was modified accordingly

Reviewer 3 Report

Authors should take a look at the attached manuscript and the comments therein. It will significantly improve the manuscript if well attended to

Comments for author File: Comments.pdf

The idea of using bacterial strains to bioremediate PFOA and PFOS is a novel idea, however, the poor construction of English language made the manuscript to appear complex. The authors should go for extensive English editing to remove certain words some of them were highlighted. 

Author Response

Thank you very much for your time and for the attention with which you went through our manuscript and for the comments made on it!
I responded to the document sent for review and all the indicated changes were made in the revised version of the manuscript.

Author Response File: Author Response.pdf

Reviewer 4 Report

1. what are the standard concentrations of PFOA and PFOS for LC/MS?

2. I hope the analysis of PFOA and PFOS were add the ''internal standards'' in the future work.

3. Did you use the filter to pass the analyzed solution with PFOA and PFOS? The filter style will capture them. Only the ''glass fiber filter'' is suitable.

4. Table S1 is a very important information. I suggest you to change it to Table 1.

5. In the results section, you just describe your data without other references. At least, I search many papers about this topic. The Introduction section also mentioned a lot of previous articles. Please, add some discussion with other references into your data.

Author Response

Thank you very much for your time and for the attention with which you went through our manuscript and for the comments made on it!
You can find the answers to the comments below, and all the indicated changes were made in the revised version of the manuscript.

Q1: what are the standard concentrations of PFOA and PFOS for LC/MS

A1: Two standard solutions were analyzed for each sample section, the concentrations being situated near the two extremes of the calibration curve, namely 1 ug/L and 75 ug/L.

Q2: I hope the analysis of PFOA and PFOS were add the ''internal standards'' in the future work.

A2: We will use the internal standards in the future work

Q3: Did you use the filter to pass the analyzed solution with PFOA and PFOS? The filter style will capture them. Only the ''glass fiber filter'' is suitable.

A3: No, it wasn’t necessary. The centrifuged procedure was sufficient to sedimentation of the precipitate. Then the supernatant was collected using an automatic analytical pipette.

Q4: Table S1 is a very important information. I suggest you to change it to Table 1.

A4: Table S1 was added to the manuscript as Table 1

Q5: In the results section, you just describe your data without other references. At least, I search many papers about this topic. The Introduction section also mentioned a lot of previous articles. Please, add some discussion with other references into your data.

A5: Discussions regarding the results obtained in other studies were performed in the Discussion section. We added to this section some comments regarding the biotransformation products identified in other studies.  

Round 2

Reviewer 3 Report

The manuscript has improved significantly based on observable corrections effected by the authors

The quality of English has improved but effort could still be made for minor input

 

 

Reviewer 4 Report

none.