Hybrid Catalysts from Copper Biosorbing Bacterial Strains and Their Recycling for Catalytic Application in the Asymmetric Addition Reaction of B₂(pin)₂ on α,β-Unsaturated Chalcones

Round 1

Reviewer 1 Report

In the title, the name of the organic reaction should be mentioned. 

Why did the authors select the class of chalcone-derivatives for their investigation? Please add a paragraph about the importance of chalcones in the introduction by citing relevant articles and review articles.  

Copper catalysis is interesting for many readers, So please add a specific paragraph in the introduction about this topic by citing relevant references. "https://onlinelibrary.wiley.com/doi/abs/10.1002/aoc.5600". As mentioned in this review article, a diverse range of reactions catalyzed by copper species are available in the literature. These reactions can be catalyzed by the catalysts from copper bio-sorbing bacterial strains. 

If possible please provide TEM analysis before and after absorption of copper(II).

If possible please provide the XPS spectrum after absorption of copper species.

Please change "their recycle" in the title to "their recycling".

In the abstract:

"1,10-phenanthroline-copper complex was exploited" should be changed to "The 1,10-phenanthroline-copper complex was exploited". Otherwise, "1,10-phenanthroline-copper complex" should be changed to "1,10-Phenanthroline-copper complex". 

"resulted the worst one." should be changed to "resulted in the worst one."

In the keywords:

"heavy-metals recycle" should be changed to "heavy-metals recycling"

In the introduction

" result accumulated in living organisms" should be changed to " result in accumulation in living organisms"

"can be both bound to the cell surface (EPS 71
bound) and free in solution" What does "both" refer to?

The conclusion should be shortened. 

Author Response

We thank the reviewers for their suggestions. Accordingly, the manuscript has been thoroughly revised.

In particular, the following changes have been made:

 

RESPONSE to #1 REVIEWER’S COMMENTS

• In the title, the name of the organic reaction should be mentioned. We added it.
• Why did the authors select the class of chalcone-derivatives for their investigation? Please add a paragraph about the importance of chalcones in the introduction by citing relevant articles and review articles.  We added a paragraph in the introduction (see lines 102-118).
• Copper catalysis is interesting for many readers, So please add a specific paragraph in the introduction about this topic by citing relevant references. "https://onlinelibrary.wiley.com/doi/abs/10.1002/aoc.5600". As mentioned in this review article, a diverse range of reactions catalyzed by copper species are available in the literature. These reactions can be catalyzed by the catalysts from copper bio-sorbing bacterial strains. Thank you very much for the suggestion for further applications. We added a paragraph in the introduction (see lines 88-97).
• If possible please provide TEM analysis before and after absorption of copper(II). If possible please provide the XPS spectrum after absorption of copper species. Thank you for the suggestion but unfortunately, we have not the possibility to perform XPS experiments. For TEM analysis, we have a problem with the broken instrument available in our institution. So, we asked for external analysis and we are in the two months waiting list. However, we introduced EPX analysis in association with elemental analysis to add major information about the composition of the bacteria with or without copper.
• Please change "their recycle" in the title to "their recycling". We did it.
• In the abstract: "1,10-phenanthroline-copper complex was exploited" should be changed to "The 1,10-phenanthroline-copper complex was exploited". Otherwise, "1,10-phenanthroline-copper complex" should be changed to "1,10-Phenanthroline-copper complex". "resulted the worst one." should be changed to "resulted in the worst one." We corrected them.
• In the keywords: "heavy-metals recycle" should be changed to "heavy-metals recycling". We changed it.
• In the introduction: "result accumulated in living organisms" should be changed to " result in accumulation in living organisms" We changed it.
• "can be both bound to the cell surface (EPS 71 bound) and free in solution" What does "both" refer to? The term “both” is referred to EPS bound and EPS unbound.
• The conclusion should be shortened. We reduced the conclusion as requested, by erasing what we considered unnecessary information.

Author Response File: Author Response.pdf

Reviewer 2 Report

The research Article, Hybrid catalysts from copper bio-sorbing bacterial strains and their recycle for catalytic application, by Gandolfi and co-workers described their efforts to explore the capabilities of different bacterial trains to adsorb copper and the feasibility of using bacteria adsorbed copper as catalyst for the synthesis of chiral alcohols. They identified the bacterial strain with a better performance for copper removal from water and optimized the copper catalyzed addition reaction conditions to yield better conversion rate and selectivity. Although overall the paper reads well, there are a few issues that need to be addressed before a consideration for publication.

 

 

1. All the bar graphs do not have error bars. I wonder how reproducible these results are.
2. For the supporting information, it might be better to separate the results with the experimental methods. Currently, the results are embedded in the methods section.
3. There are several typos and grammar mistakes that need to be corrected. For example, line 14, “make it difficult their removal efficiency”; line 89, “not more useful”; line 116, “it possible to…”; line 246-249, this sentence may need to be rephrased; line 214, “the reaction resulted to proceed”.
4. Figure 1, 200 mg/L CuCl2 was used. Can the authors explain why such a concentration was used? Is this considered to be relevant to the copper concentration in industrial wastewater? In addition, after copper removal by bacteria, is the amount of left-over cooper in water still considered to be high? Are these bacterial trains capable of removing lower concentrations of copper from water?
5. Line 144-154 and figure 2, the adsorption conditions were optimized. Did the author test a range of different concentrations of copper? And what is the concentration range?
6. Line 182-190, the authors did not show the NMR spectra from 13A strain. It is critical to show them in comparison to SC5II.
7. Line 191-201, can the authors elaborate more on these DLS, SEM and IR results? What insights did these results provide? It seems to be very vague to me.  
8. Line 198, there is no TABLE 13 in this paper.
9. Line 213, the first sentence needs grammar check.
10. Line 238, “as shown in figure 4”, maybe it should be as shown in scheme 1.
11. Figure 4, these numbers do not have a unit.

 

Author Response

We thank the reviewers for their suggestions. Accordingly, the manuscript has been thoroughly revised.

In particular, the following changes have been made:

 

RESPONSE to #2 REVIEWER’S COMMENTS

1. All the bar graphs do not have error bars. I wonder how reproducible these results are. We added error bars in the graphs. All tests were reproduced three times and SD were added to all the Figures data.
2. For the supporting information, it might be better to separate the results with the experimental methods. Currently, the results are embedded in the methods section. We changed it.
3. There are several typos and grammar mistakes that need to be corrected. For example, line 14, “make it difficult their removal efficiency”; line 89, “not more useful”; line 116, “it possible to…”; line 246-249, this sentence may need to be rephrased; line 214, “the reaction resulted to proceed”. We corrected them and we re-wrote the sentence.
4. Figure 1, 200 mg/L CuCl2 was used. Can the authors explain why such a concentration was used? Is this considered to be relevant to the copper concentration in industrial wastewater? We used this Cu concentration because it is relevant in wastewaters from electroplating industry. Effluents are typically in the Cu concentration range of 100-500 mg/L. Please see the revised text at page 2 L 96-99: “Strains were grown on LB medium and tested for their ability to remove copper supplied as 200 mg/L CuCl₂ (see Line 124-126)
5. In addition, after copper removal by bacteria, is the amount of left-over cooper in water still considered to be high? The left-over copper was about 120 mg/L, far exceeding the law limits of 1 mg/L (D.Lgs. 152, 2006). Please see the revised text at page 3 L 144-149: “Considering the higher biosorption ability of the Serratia plymuthica strains tested in the present study, future analyses will be performed in order to envisage their use in Cu(II) biorecovery and bioremediation of heavy metal contaminated industrial wastewaters.
6. Are these bacterial trains capable of removing lower concentrations of copper from water? The authors are aware of this issue and these trials are currently running. Data will be presented in future manuscript regarding metal adsorption models.
7. Line 144-154 and figure 2, the adsorption conditions were optimized. Did the author test a range of different concentrations of copper? And what is the concentration range? We inserted the concentration details.
8. Line 182-190, the authors did not show the NMR spectra from 13A strain. It is critical to show them in comparison to SC5II. We introduced it in SI.
9. Line 191-201, can the authors elaborate more on these DLS, SEM and IR results? What insights did these results provide? It seems to be very vague to me.  We added a sentence and additional experiments.
10. Line 198, there is no TABLE 13 in this paper. We are very sorry but probably, during the insertion by editorial office of the manuscript in the template, part of the sentence was lost.
11. Line 213, the first sentence needs grammar check. See point 3.
12. Line 238, “as shown in figure 4”, maybe it should be as shown in scheme 1. We changed it.
13. Figure 4, these numbers do not have a unit. The percentage was calculated as mols of product/mols of reagent thus the results are reported as %.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I have no further comments on the document.

Reviewer 2 Report

The authors have addressed my comments.