Microbial-Based Heavy Metal Bioremediation: Toxicity and Eco-Friendly Approaches to Heavy Metal Decontamination
Laleh Yerushalmi
Round 1
Reviewer 1 Report
This is an important review of the literature. But before it is published
I expect corrections and clarifications:
1. My basic comment concerns the cited literature items, which in my opinion are not related to the described issue:
line 31 - this reference [1] does not fit the statemet in lines 30-31,
line 38 - reference [4] - the same,
line 51 - reference [7] - the same,
line 58 - reference [10] - the same
line 66 - reference [13] - the same,
line 81 - reference [16] - the same,
line 102 - reference [20] - the same,
line 114 - reference [23] - the same,
line 116 - reference [24] - the same,
line 147 - reference [33] - the same,
line 239 - reference [55] - the same,
line 435 - reference [14] - the same,
2. line 120 - You used ROS abbreviation for the first time in this lie, without the explanation. I found the expalnation in line 399 "Reactive oxygen species (ROS)" which is to late,
3. line 130 - You use in yopur article the quote method with square brackets,
[ ], so please repalce this:"according to Saper et al. (2008)" by another solution,
4. Lines: 327- 328 - please remove this statement "which is effectively and efficiently utilized as a visual representation of data",
Author Response
This is an important review of the literature. But before it is published. I expect corrections and clarifications:
Reviewer comment 1. My basic comment concerns the cited literature items, which in my opinion are not related to the described issue:
line 31 - this reference [1] does not fit the statement in lines 30-31,
line 38 - reference [4] - the same,
line 51 - reference [7] - the same,
line 58 - reference [10] - the same
line 66 - reference [13] - the same,
line 81 - reference [16] - the same,
line 102 - reference [20] - the same,
line 114 - reference [23] - the same,
line 116 - reference [24] - the same,
line 147 - reference [33] - the same,
line 239 - reference [55] - the same,
line 435 - reference [14] - the same,
Author response: Authors are thankful to the reviewer for their valuable suggestions.
The related citations have been updated in the revised manuscript.
Reviewer comment 2. line 120 - You used ROS abbreviation for the first time in this lie, without the explanation. I found the expalnation in line 399 "Reactive oxygen species (ROS)" which is to late,
Author response: The suggested correction has been made in the revised manuscript. We have used the explanation “Reactive oxygen species (ROS) at page 3, section 2.2.1.
Reviewer comment 3. line 130 - You use in yopur article the quote method with square brackets,
[ ], so please repalce this:"according to Saper et al. (2008)" by another solution.
Author’s response: The suggestion correction has been made in the revised manuscript as “Saper et al [28].”
Reviewer comment 4. Lines: 327- 328 - please remove this statement "which is effectively and efficiently utilized as a visual representation of data",
Author’s response: The suggested statement has been removed from the revised manuscript.
Reviewer 2 Report
Point 3.6.1. lack of sufficient information about rhizoremediation, for instance the figure 2 has more information than in the text – this information needs to be commented in the text;
the abbreviations HMs (haevy metals) and HM (hazardous materials) raise objections, why introduce them if they are not used in the text anyway...?
Line 7 – china – China
Line 32 – is everything ok with this sentence?
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These heavy metals and metalloids have the potential to |
32 |
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accumulate from various sources such as air and water, infiltrating plants, animals, and |
33 |
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humans, and subsequently advancing through the food chain
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Line 112 - central pollution control board – in which country
Line 120 – lack of extension of ROS
Author Response
Reviewer comment: Point 3.6.1. lack of sufficient information about rhizoremediation, for instance the figure 2 has more information than in the text – this information needs to be commented in the text;
Author’s response: Section 3.6.1 has been updated in the revised manuscript.
Reviewer comment: The abbreviations HMs (haevy metals) and HM (hazardous materials) raise objections, why introduce them if they are not used in the text anyway...?
Author’s response: We have used full form of HMs as heavy metals (HM = Heavy metal) and remove abbreviations from revised manuscript.
Reviewer comment: Line 7 – china – China
Author’s response: The correction has been made in the revised manuscript.
Reviewer comment: Line 32 – is everything ok with this sentence?
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These heavy metals and metalloids have the potential to |
32 |
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accumulate from various sources such as air and water, infiltrating plants, animals, and |
33 |
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humans, and subsequently advancing through the food chain |
Author’s response: The given sentences have been rewritten in the revised manuscript as “Heavy metals occur naturally within the earth's crust [1]. Nonetheless, due to their recalcitrant properties, they exhibit resistance towards degradation. These heavy metals have the potential to accumulate in the human and animals from soil and water by entering into the food chain [2].”
Reviewer comment: Line 112 - central pollution control board – in which country
Author’s response: central pollution control board (CPCB), India. We have updated in the revised manuscript.
Reviewer comment: Line 120 – lack of extension of ROS
Author’s response: Correction has been made in the revised manuscript.
Reviewer 3 Report
Comments:
- The Abstract and Conclusions sections have very similar contents. The Conclusions section should summarize the results of the study and present conclusive remarks, not repeating the content of the Abstract.
- Line 120: ROS (reactive oxygen species) should be spelled out.
- Lines 282-283: Please elaborate on the role of the pKa value of the medium in which the biosorption occurs in the adsorption of heavy metal ions.
- Lines 386 and 389 and other places on the manuscript: Please mention the existing concentrations of heavy metals in wastewater and the changes in their corresponding concentrations in addition to their removal percentages.
- Table 2: The corresponding concentrations of heavy metals before and after the uptake process should be included in the table. The removal percentage is not sufficient as it does not specify the implicated concentration range of heavy metals.
- Line 452: Please verify the oxidation state of arsenic.
- Section 3.6.1: It would be helpful to move the paragraph starting on line 487 on the mechanism of Rhizoremediation to the beginning of this section.
Author Response
Reviewer‘s comment: The Abstract and Conclusions sections have very similar contents. The Conclusions section should summarize the results of the study and present conclusive remarks, not repeating the content of the Abstract.
Author’s response: The conclusion section has been updated in the revised manuscript.
Reviewer‘s comment: Line 120: ROS (reactive oxygen species) should be spelled out.
Author’s response: The suggested correction has been done in the revised manuscript file.
Reviewer‘s comment: Lines 282-283: Please elaborate on the role of the pKa value of the medium in which the biosorption occurs in the adsorption of heavy metal ions.
Author’s response: The role of pKa has been elaborated in the revised manuscript (section 3.2).
Reviewer‘s comment: Lines 386 and 389 and other places on the manuscript: Please mention the existing concentrations of heavy metals in wastewater and the changes in their corresponding concentrations in addition to their removal percentages.
Author’s response: Authors are thankful to the reviewer‘s suggestion. The initial concentration of heavy metal ions has been updated in the revised manuscript.
Reviewer‘s comment: Table 2: The corresponding concentrations of heavy metals before and after the uptake process should be included in the table. The removal percentage is not sufficient as it does not specify the implicated concentration range of heavy metals.
Reviewer‘s comment: Line 452: Please verify the oxidation state of arsenic.
Author’s response: The oxidation state has been corrected in the revised manuscript as As(V).
Reviewer‘s comment: Section 3.6.1: It would be helpful to move the paragraph starting on line 487 on the mechanism of Rhizoremediation to the beginning of this section.
Author’s response: Authors are thankful to the reviewer for his suggestion. The suggested correction has been made in the revised manuscript.
Reviewer 4 Report
Article is written in good English. However, readers do not have much from reading the present review, no added value, review is too general written, not comprehensively. In-depth explanations of presented methods are missing, therefore, the review seam not scientific. In every part of chapter 3 additional explanations are required.
In title are words "eco-friendly approaches": e.g. bio-accumulation is just transfer of metals from soil into plant, please explain how the problem of heavy metal is solved this way? In my opinion it is not!
Specific errors:
L116: "... these permissible limits..." Which limits?
Figure 1: CAT and GST in Figure 1 are not explained, what does it mean?
From which literature is Figure 1? Cite.
Table 2: How can be capacity expressed in %?? It is not clear at all. Please explain.
e.g. L 451:
"....As (III) into compounds that are comparatively less soluble and non-poisonous As (III)..." Which are these compounds -they have to be described!
L 491: "...PGPB..." is mentioned and not explained how it works, mechanism of soil renewal with these bacteria?? The explanation is required.
L500: ".... alleviating soil contamination caused...." In abstract is written that it would be explained "... development of biological wastewater treatment systems..." and also in L93: where is now the connection? Please carefully check your writing and focus either on removal of heavy metals from soil or from wastewater.
Chapter 3.6.1: Novel approaches are not explained et all, what are GEMs, how does it work - explanation is strongly required! In last paragraph CRISPR is just mentioned: since it is a new technology must be explained more in detail with some additional cited references. It is not clear what does CRISPR mean, what is the main mechanism?
Literature is not uniform cited: sometimes abbreviations are not used (44,45), sometimes in italic (45). Please check all references, not only mentioned!!
Minor editing
Author Response
Reviewer‘s comment: Article is written in good English. However, readers do not have much from reading the present review, no added value, review is too general written, not comprehensively. In-depth explanations of presented methods are missing, therefore, the review seam not scientific. In every part of chapter 3 additional explanations are required.
Author’s response: Authors are thankful to the reviewer for his encouragement and valuable suggestions. We have updated Chapter 3 in the revised manuscript with new information related to the manuscript area.
Reviewer‘s comment: In title are words "eco-friendly approaches": e.g. bio-accumulation is just transfer of metals from soil into plant, please explain how the problem of heavy metal is solved this way? In my opinion it is not!
Author’s response: The bio-accumulation process is known as the transfer of heavy metals from contaminated sites (contaminated soil & water) into microbes or plants. In the plant system, this phenomenon is known as phytoremediation. The main problem regarding the complete solution of heavy metal contamination can be solved and this process is known as Phytoextraction. The term phytoextraction is related to the translocation of heavy metal ions from soil and gets accumulates in the stem, root and leaves till reached saturation limit. After reaching the saturation limit plants need to cut and dispose. We have mentioned the Phytoextraction process in section 3.6.1.
Specific errors:
Reviewer‘s comment: L116: "... these permissible limits..." Which limits?
Author’s response: The permissible limit of heavy metals in industrial effluent should be less than 0.1 mg/L (As), 0.01 mg/L (Cd), 0.05 mg/L (Cr6+), 0.1 mg/L (Pb) and 0.5 mg/L (Ni). We have mentioned these values in the revised manuscript.
Reviewer‘s comment: Figure 1: CAT and GST in Figure 1 are not explained, what does it mean?
Author’s response: Catalase (CAT) and glutathione-S-transferase (GST) are antioxidant and these explanation have been mentioned in the revised manuscript.
Reviewer‘s comment: From which literature is Figure 1? Cite.
Author’s response: Figure 1 informations have been obtained from “Singh et al. 2023, Toxics 2023, 11(2), 147; https://doi.org/10.3390/toxics11020147”. This paper has been cited in the revised manuscript.
Reviewer‘s comment: Table 2: How can be capacity expressed in %?? It is not clear at all. Please explain.
Author’s response: The % removal capacity in the Table 2 was calculated as % removal of heavy metals from contaminated water after treatment process. The removal capacity of microorganisms can express as (Equation 1)
Removal (%) = × 100 (1)
where Co and Ce are the initial and equilibrium (after treatment) concentration of heavy metals (mg/L).
Reviewer‘s comment: e.g. L 451:"....As (III) into compounds that are comparatively less soluble and non-poisonous As (III)..." Which are these compounds -they have to be described!
Author’s response: The most common compounds of As (III) are arsenic trioxide, sodium arsenite and arsenic trichloride, and arsenic pentoxide is arsenic acid and arsenates (e.g. lead arsenate and calcium arsenate) are the most common pentavalent compounds (As(V)). We have updated this explanation in the revised manuscript.
Reviewer‘s comment: L 491: "...PGPB..." is mentioned and not explained how it works, mechanism of soil renewal with these bacteria?? The explanation is required.
Author’s response: The explanation of PGPB has been updated in the revised manuscript in section 3.6.1
Reviewer‘s comment: L500: ".... alleviating soil contamination caused...." In abstract is written that it would be explained "... development of biological wastewater treatment systems..." and also in L93: where is now the connection? Please carefully check your writing and focus either on removal of heavy metals from soil or from wastewater.
Author’s response: We are thankful to the reviewer for this suggestion. We have updated the abstract section and corrected the writing style to connect with the abstract.
Reviewer‘s comment: Chapter 3.6.1: Novel approaches are not explained et all, what are GEMs, how does it work - explanation is strongly required! In last paragraph CRISPR is just mentioned: since it is a new technology must be explained more in detail with some additional cited references. It is not clear what does CRISPR mean, what is the main mechanism?
Author’s response: Authors are thankful to the reviewer for his valuable suggestions. We have added explanation regarding GEMs and CRISPR in the revised manuscript.
Reviewer‘s comment: Literature is not uniform cited: sometimes abbreviations are not used (44, 45), sometimes in italic (45). Please check all references, not only mentioned!!
Author’s response: The citations in the manuscript have been checked and corrected in the revised manuscript.
Reviewer 5 Report
The work lacks novelty and structure. First of all, it is not clear which time interval the analysed papers refer to and which search string was used. Furthermore, it is also necessary to include how this string was constructed and why a specific time interval was focused on.
Next, the number of analysed papers must be reported.
The paragraph dealing with the sources of these heavy metals is too short and should be expanded, while the one on effects is excessively long-winded. In fact, for the purposes of the review, an understanding and definition of the industrial (and non-industrial) sources of the contaminants is much more important than a description of their effects on the environment. It is therefore necessary to expand the descriptions of sources and increase the number of supporting citations.
It is not clear whether the focus of the review is all heavy metals or only some. Only Pb, Cd, Cr, As and Cu are mentioned in the tables. Sporadically, others are also named. The heavy metals are far more and these represent the most common and known ones, making the work poor in novelty. It would be good to expand by including other, less common heavy metals such as Vanadium, Thallium and Nickel.
Otherwise, define an objective basis for selecting a certain number of metals for consideration.
For each technology, the number of papers dealing with this technology is not defined, nor how according to these papers these technologies are applied.
In addition, a comparison between technologies on the basis of the individual contaminant is missing. I would also have expected a table showing how for each heavy metal there are removal effects. Furthermore, it is important to specify the starting contamination in addition to the percentage removal.
In conclusion, the paper is clearly written but, in my opinion, needs revision work and the definition of objectives and methodology for paper selection. The chapter on "technology challenges and future prospects" also needs to be expanded, as it represents the true core of the paper and thus the enrichment that this work brings to the scientific literature.
The manuscript is well written. Really easy to understand and read.
Author Response
Reviewer‘s comment: The work lacks novelty and structure. First of all, it is not clear which time interval the analysed papers refer to and which search string was used. Furthermore, it is also necessary to include how this string was constructed and why a specific time interval was focused on. Next, the number of analysed papers must be reported.
The paragraph dealing with the sources of these heavy metals is too short and should be expanded, while the one on effects is excessively long-winded. In fact, for the purposes of the review, an understanding and definition of the industrial (and non-industrial) sources of the contaminants is much more important than a description of their effects on the environment. It is therefore necessary to expand the descriptions of sources and increase the number of supporting citations.
Author’s response: Authors are thankful to the reviewer for his comments and valuable suggestions. The manuscript has been updated and quality. We have updated the section “Source of heavy metals”. The information regarding industrial and non-indusrtial sources of heavy metal contamination according to reviewer suggestions has been updated in the revised manuscript.
Reviewer‘s comment: It is not clear whether the focus of the review is all heavy metals or only some. Only Pb, Cd, Cr, As and Cu are mentioned in the tables. Sporadically, others are also named. The heavy metals are far more and these represent the most common and known ones, making the work poor in novelty. It would be good to expand by including other, less common heavy metals such as Vanadium, Thallium and Nickel.
Otherwise, define an objective basis for selecting a certain number of metals for consideration.
Author’s response: This review basically focused on the certain heavy metals such as As, Pb, Cd, Cr and Cu cause contamination in the water. We have change objective as per reviewer‘s suggestion in the revised manuscript. The changes have been made in the revised manuscript in the end of the introduction section.
Reviewer‘s comment: For each technology, the number of papers dealing with this technology is not defined, nor how according to these papers these technologies are applied.
In addition, a comparison between technologies on the basis of the individual contaminant is missing. I would also have expected a table showing how for each heavy metal there are removal effects. Furthermore, it is important to specify the starting contamination in addition to the percentage removal.
Author’s response: Authors are thankful for the reviewer‘s suggestion. The suggested corrections have been made in the revised manuscript section. We have updated Table 2 with the initial concentration used for the removal of heavy metals.
Reviewer‘s comment: In conclusion, the paper is clearly written but, in my opinion, needs revision work and the definition of objectives and methodology for paper selection. The chapter on "technology challenges and future prospects" also needs to be expanded, as it represents the true core of the paper and thus the enrichment that this work brings to the scientific literature.
Reviewer‘s comment: The manuscript is well written. Really easy to understand and read.
Author’s response: The authors are thankful to the reviewer for the encouragement of our work.
Reviewer 6 Report
The manuscript entitled "Microbial based heavy metal bioremediation: Toxicity and eco- friendly approaches for heavy metal decontamination" is immaturely design and presented. The work is an unsuccessful blend of well - known notions with insignificant aspects from some specialty literature papers. Furthermore, in the text a poetic way of writing is used at some places instead of a technical one. The manuscript could be published only after major revisions. I made the following comments:
- The abstract does not reflect the work essence and should be reformulated:
- The novelty of the work must be clearly addressed and discussed, compare your research with existing research findings and highlight novelty;
- The main objective of the work must be written on the more clear and more concise way at the end of introduction section.
- Authors must establish a connection between state of the art and your paper's objectives in the introduction. Please follow the literature review with a concise and clear analysis of the state of the art;
- Line 112-115: To tackle the issue of heavy metal discharge in industrial effluent, the Cen-
tral Pollution Control Board (CPCB) has laid down the maximum permissible limit for
heavy metals [4, 23]. Similarly, the United States Environmental Protection Agency
(USEPA) has also established the maximum allowable limit of heavy metals present in
drinking water . What are these limits?
- Line 165: "Heavy-mediated carcinogenicity " What means this?
- The authors does not give insight into the presentation and discussion of results There are no own opinions and critical views.
- The Tables are very poor in information;
- The conclusions part is mainly a repetition of the abstract; it needs to be rewritten.
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Moderate editing of English is required.
Author Response
The manuscript entitled "Microbial based heavy metal bioremediation: Toxicity and eco- friendly approaches for heavy metal decontamination" is immaturely design and presented. The work is an unsuccessful blend of well - known notions with insignificant aspects from some specialty literature papers. Furthermore, in the text a poetic way of writing is used at some places instead of a technical one. The manuscript could be published only after major revisions. I made the following comments:
Reviewer‘s comment: The abstract does not reflect the work essence and should be reformulated:
Author’s response: The have been updated in the revised manuscript.
Reviewer‘s comment: The novelty of the work must be clearly addressed and discussed, compare your research with existing research findings and highlight novelty;
Author’s response: Authors are grateful to the reviewer for valuable suggestion. The manuscript have been updated and many new facts have been added in the revised manuscript. We have updated comparative Table 2 for better clearity. For novelty purpose we have updated introduction section including sources and remediation sections of the revised manuscript.
Reviewer‘s comment: The main objective of the work must be written on the more clear and more concise way at the end of introduction section.
Author’s response: The suggested correction has been made in the revised manuscript.
Reviewer‘s comment: Authors must establish a connection between state of the art and your paper's objectives in the introduction. Please follow the literature review with a concise and clear analysis of the state of the art;
Author’s response: We have corrected the objective of the manuscript section and updated revised manuscript according to objective and added my new information in the revised manuscript.
Reviewer‘s comment: Line 112-115: To tackle the issue of heavy metal discharge in industrial effluent, the Central Pollution Control Board (CPCB) has laid down the maximum permissible limit for
heavy metals [4, 23]. Similarly, the United States Environmental Protection Agency
(USEPA) has also established the maximum allowable limit of heavy metals present in
drinking water . What are these limits?
Author‘s response: We have mentioned these values in the revised manuscript
Reviewer‘s comment: Line 165: "Heavy-mediated carcinogenicity " What means this?
Author‘s response: Heavy metal mediated carcinogenicity mean toxic effects of heavy metals on human effects and this heavy metal toxicity responsible for development of cancer in the humans.
Reviewer‘s comment: The authors does not give insight into the presentation and discussion of results There are no own opinions and critical views.
Author‘s response: Authors are thankful to the reviewer for valuable suggestion. This is the review paper and we will follow reviewer’s instructions in the future research publications.
Reviewer‘s comment: The Tables are very poor in information
Author‘s response: We have upated table 2 and added initial metal ions concentration for better comparative study.
Reviewer‘s comment: The conclusions part is mainly a repetition of the abstract; it needs to be rewritten.
Author‘s response: The conclusion section has been updated in the revised manuscript.
Round 2
Reviewer 4 Report
Article was suitable improved.
I am not satisfied with response regarding Phytoextraction: I still believe it is transfer of metals from soil into the plant and nothing more. Author itself explained:
"The term phytoextraction is related to the translocation of heavy metal ions from soil and gets accumulates in the stem, root and leaves till reached saturation limit. After reaching the saturation limit plants need to cut and dispose"
Thus, explain where is the benefit???
Author Response
Comment: Article was suitable improved.
Author ‘s response: Authors are thankful to the reviewer for his appreciation and acceptance of the revision.
Comment: I am not satisfied with response regarding Phytoextraction: I still believe it is transfer of metals from soil into the plant and nothing more. Author itself explained:
"The term phytoextraction is related to the translocation of heavy metal ions from soil and gets accumulates in the stem, root and leaves till reached saturation limit. After reaching the saturation limit plants need to cut and dispose"
Thus, explain where is the benefit???
Author‘s response: We have corrected the manuscript regarding Phytoextraction as per the reviewer‘s suggestion regarding Phytoextraction as “Phytoextraction is the process in which transfer of heavy metals from soil into the plant.”
Phytoextraction is beneficial for the extraction of heavy metals from contaminated sites by plants.
Reviewer 5 Report
The requested changes have been made, greatly improving the quality of the manuscript.
Author Response
Comment: The requested changes have been made, greatly improving the quality of the manuscript.
Author‘s response: Authors are thankful to the reviewer for his appreciation and acceptance of the revision.
Reviewer 6 Report
The manuscript can be published only after minor revisions. The authors do not give insight into the presentation and discussion of results. There are no own opinions and critical views. The response of the authors to this comment is completely unsatisfactory.
It still required moderate editing of English language
Author Response
Comment: The manuscript can be published only after minor revisions. The authors do not give insight into the presentation and discussion of results. There are no own opinions and critical views. The response of the authors to this comment is completely unsatisfactory.
Author‘s response: Authors are grateful for the reviewer‘s suggestion and apologise for the unsatisfactory response during the first revision.
In this revision, we have highlighted our own opinions and critical views on the facts included in this review. We have summarised our own opinion and critical views in section 4.0 Technology Challenges and concluded it with our own opinion in section 5.0 Conclusion.
Comment: It still required moderate editing of English language
Author‘s response: The revised manuscript has been checked and corrected English throughout the revised manuscript.
