Tolerance and Cadmium (Cd) Immobilization by Native Bacteria Isolated in Cocoa Soils with Increased Metal Content

Round 1

Reviewer 1 Report

Manuscript entitled „ Tolerance and Cadmium (Cd) Immobilization by Native Bacteria Isolated in Cocoa Soils with Presence of Metal” submitted to Microbiology Research is well written and the results are presented in a logical and coherent manner. The paper is adequately organized and the topic is interesting and focuses on current problems.

Although the manuscript is well-organized and prepared, however, small improvements should be introduced that will improve its quality:

1.       Fig 1: Please change the description of the y axis from “Absorbance” to “Optical density” or O.D. In addition, in the description for the figure 1, use the following notation: 0 mg Cd / L , 15 mg Cd/L etc. Please also change the unit notation in the text and in the description of other figures

2.       “Conclusion” part : please indicate direction for future research and propose some improvements and challenges

 

Manuscript should be accepted for publication and authors should be prepared to incorporate minor revisions.

 

Author Response

Thanks a lot for your comments. "Please see the attachment"

Author Response File: Author Response.docx

Reviewer 2 Report

The use of bacteria is one of the strategies for the metal biostabilization in soils, because biosorption/bioaccumulation by bacterial biomass can decrease metal translocation from soil to plants. The manuscript describes the cadmium-resistant strains isolated from the cocoa soil, effect of Cd on growth of these bacteria, tolerance of Cd by these bacteria, as well as the metal immobilization on the cell surface (biosorption ability) and intracellular accumulation. Authors used the TEM, EDX and FTIR analysis to determine mechanisms of Cd interaction with bacterial cells. Also the pot experiment with young cacao plants was made. Authors analyzed: (1) Cd concentration in chemicals, (2) biomass of roots and shoots, (3) Cd accumulation in cacao plants, (4) bioconcentration and translocation factors. The study seems thoroughly designed and competently executed. The manuscript is detailed and comprehensive.

Specific comments:

1. I suggest changing the title, e.g. “Cadmium tolerance and immobilization by native bacteria isolated from cocoa soil with increased this metal content”

2. How many strains was used? Ten (line 67) or twelve (line 12, Table 1)?

3. Lines 71 – 77. “Here, we present high Cd-resistant bacterial strains with biosorption ……… native bacteria is one of the strategies for bioremediation to applied in soil cocoa crops with Cd geogenic presence.” This fragment is a conclusion, and should be moved to the chapter no. 5.

4. Line 158. What was the basal concentration of Cd in the soil? Was this soil contaminated? How much  the permissible Cd content in the soil was exceeded?

5. Table 1. According to me, codes can be deleted. Bacterial strains were taxonomically identified. The names of the bacteria, without the codes, should be used throughout.

6. Table 2. The µ, g and K growth variables should be explain. Let's remember about the educational role of the article. Besides, Authors did not mention about these parameters in the methodology.

7. Table 2 and Table 3.  Cupriavidus metallidurans as reference strain should be enter in the first verse.

8. Table 3. The title of this table does not reflect its content.

9. Line 258. How soil and chemicals were analyzed?  It should be mentioned in the methodology. My proposition is: “Properties and textural class of the soil were determined according to ……. Cd concentrations in the soil and chemicals were analyzed using ………… method.”

10.Table 6. Please enter the names of the bacteria instead of "bacteria 1, bacteria 2, bacteria 3".

11. 5. Conclusion. Conclusions from the greenhouse experiment are missing. Please complete. Which bacteria should be recommended for Cd biostabilization?

 

 

Author Response

Thanks a lot for your comments. 

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

This manuscript reports a study on the tolerance and Cd immobilization by twelve cadmium-tolerant soil bacteria. A pot study with cocoa plants was also conducted to assess the effect of inoculated bacterial strains under different concentration of Cd.

 

This is an interesting study, which was technically well conducted.

 

The English language is poor and needs to be significantly improved throughout the manuscript. I suggest that the manuscript should be revised by an English native speaker.

 

L12: native to where?

L71-77: these results should be removed from the introduction.

L87: replace “mediums” with “”media”

L169: please provide the condition of the greenhouse where the plants were grown: temperature, humidity, light

L565-574: This is relative to introduction and not conclusion.

Table 3: replace “Gram tinction” with “”Gram stain”

 

The conclusion section needs to be more focused on the conclusions obtained in this study.

Author Response

Thanks for your comments.

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thank you for following the comments. At the moment, the work looks much better and can be published in the presented form.

Reviewer 3 Report

The manuscript has been revised according to my previous comments and is now ready for publication.