Polyphasic Characterization of Indigenous Potassium-Solubilizing Bacteria and Its Efficacy Studies on Maize

Round 1

Reviewer 1 Report

This study isolated and screened potassium solubilizing bacteria (KSB) from the rhizosphere soil, and examined the effect of KSB strains on the growth of maize. The results showed that KSB strains could solubilize the mineral potassium and enhance the growth of maize. This paper contains a lot of data. However, the description of the method in this paper is not clear and lack of data analysis. I list my comments below and hope these comments will help authors in their revisions.

 

Major concerns:

1. There is no data analysis in this study. The difference between treatments should be compared by proper method based on the results of normality test and variance homogeneity test.

2. The method description is not clear. The experimental results are mentioned in Materials and Methods, and the methods are described in Results and Discussions.

3. The evidence of the survival of KSB strains in the rhizosphere of maize is missing.

4. The results are not surprising, such effects of KSB is well known. What’s new in this study?

 

Minor concerns:

Abstract

Abstract should be rewritten to better summarize this study’s results.

Line 12-13 “potassium solubilizing bacteria” should be “Potassium solubilizing bacteria”

Line 20 Please clarify the meaning of “35.36, 76.04 and 56.58 μg ml-1”

Line 21-22 “These KSB strains were further screened for hydrolytic enzymes, plant growth promoting activities and tolerance to different environmental stresses”. What should be presented here is the results, not the content of the study.

Keywords: the initials of keywords donot need to be capitalized.

 

Introduction

Line 58-59 “increased K requirement has driven more worldwide production of K fertilizer leads to its higher prices”. More production of K fertilizer may lead to a decrease in price.

 

Materials and Methods

Materials and Methods should be rewritten to clarify the experimental methods. Futhermore, this part lacks data analysis.

Line 80-86 the detailed information about sampling locations should be added, such as sampling time, climatic conditions of sample plots, size of each sample plot, soil properties of each site, etc. The method of collecting rhizosphere soil should be added.

Line 88-96 the experimental results should be moved to Results and Discussions.

Line “All the sixty-five bacterial isolates were screened and optimized at different conditions such as culture media, temperature and pH”. The detailed information about conditions of culture media, temperature and pH, and the culure conditons of the strains should be added.

Line 97 the single pure colony should be aquired before screening of KSB.

Line 108-114 please state which strain was used as control.

Line 116-120 please describe these methods in detail.

Line 123-129 please indicate what primers are used.

Line 132-140 please describe these methods in detail.

Line 142-147 three replicates per treatment is not enough for pot experiment. Please add the sterilization method of the seeds and matrix. The information about the growth conditions for maized should be added, such as temperature, humidity, light intensity, etc. Whether the nutrient solution was added during the growth period of maize? Whether the maize were treated under stress?

 

Results and Discussions

Results and Discussions needs to be rewritten. There is a lot of repetition between the result part and the method part. The author needs to read the literature extensively and try to find possible reasons for the conclusions of this manuscript. The authors should strengthen the Discussion section.

Line 175 what is the meaning of “KSI”?

Line 180 what is the standard of “higher solubilization index”?

 

Tables

The data shown in the Table need to be indicated as standard deviation or standard error. The number of replications of the data should be added. The meaning of values in Table S3-S5 should added to the header.

Author Response

Reviewer 1

This study isolated and screened potassium solubilizing bacteria (KSB) from the rhizosphere soil, and examined the effect of KSB strains on the growth of maize. The results showed that KSB strains could solubilize the mineral potassium and enhance the growth of maize. This paper contains a lot of data. However, the description of the method in this paper is not clear and lack of data analysis. I list my comments below and hope these comments will help authors in their revisions.

Major concerns:

1. There is no data analysis in this study. The difference between treatments should be compared by proper method based on the results of normality test and variance homogeneity test.

Reply: Dear esteemed reviewer, we add the statically analyzed data where require, few places no need of data analysis.

2. The method description is not clear. The experimental results are mentioned in Materials and Methods, and the methods are described in Results and Discussions.

Reply: Dear esteemed reviewer, corrected in revised manuscript

3. The evidence of the survival of KSB strains in the rhizosphere of maize is missing.

Reply: Dear esteemed reviewer, corrected in revised manuscript

4. The results are not surprising, such effects of KSB is well known. What’s new in this study?

Reply: Dear esteemed reviewer, corrected in revised manuscript

Minor concerns:

Abstract

Abstract should be rewritten to better summarize this study’s results.

Reply: corrected in revised manuscript

Line 12-13 “potassium solubilizing bacteria” should be “Potassium solubilizing bacteria”

Reply: corrected in revised manuscript

Line 20 Please clarify the meaning of “35.36, 76.04 and 56.58 μg ml-1”

Reply: corrected in revised manuscript

Line 21-22 “These KSB strains were further screened for hydrolytic enzymes, plant growth promoting activities and tolerance to different environmental stresses”. What should be presented here is the results, not the content of the study.

Reply: Dear reviewer, corrected in revised manuscript

Keywords: the initials of keywords donot need to be capitalized.

Reply: corrected in revised manuscript

Introduction

Line 58-59 “increased K requirement has driven more worldwide production of K fertilizer leads to its higher prices”. More production of K fertilizer may lead to a decrease in price.

Reply: corrected in revised manuscript

Materials and Methods

Materials and Methods should be rewritten to clarify the experimental methods. Futhermore, this part lacks data analysis.

Reply: corrected in revised manuscript

Line 80-86 the detailed information about sampling locations should be added, such as sampling time, climatic conditions of sample plots, size of each sample plot, soil properties of each site, etc. The method of collecting rhizosphere soil should be added.

Reply: Dear reviewer, your suggestion is covered in rest of the places, and not relevant at this place, kindly consider this.

Line 88-96 the experimental results should be moved to Results and Discussions.

Line “All the sixty-five bacterial isolates were screened and optimized at different conditions such as culture media, temperature and pH”. The detailed information about conditions of culture media, temperature and pH, and the culure conditons of the strains should be added.

Reply: Dear reviewer, this is the further part of material and methods that’s why added here.

Line 97 the single pure colony should be aquired before screening of KSB.

Reply: corrected in revised manuscript

Line 108-114 please state which strain was used as control.

Reply: Without strain use as control.

Line 116-120 please describe these methods in detail.

Reply: corrected in revised manuscript

Line 123-129 please indicate what primers are used.

Reply: corrected in revised manuscript

Line 132-140 please describe these methods in detail.

Reply: corrected in revised manuscript

Line 142-147 three replicates per treatment is not enough for pot experiment. Please add the sterilization method of the seeds and matrix. The information about the growth conditions for maized should be added, such as temperature, humidity, light intensity, etc. Whether the nutrient solution was added during the growth period of maize? Whether the maize were treated under stress?

Reply: corrected in revised manuscript

 Results and Discussions

Results and Discussions needs to be rewritten. There is a lot of repetition between the result part and the method part. The author needs to read the literature extensively and try to find possible reasons for the conclusions of this manuscript. The authors should strengthen the Discussion section.

Line 175 what is the meaning of “KSI”?

Reply: corrected in revised manuscript

Line 180 what is the standard of “higher solubilization index”?

Reply: corrected in revised manuscript

 Tables

The data shown in the Table need to be indicated as standard deviation or standard error. The number of replications of the data should be added. The meaning of values in Table S3-S5 should added to the header.

Reply: corrected in revised manuscript

 

Reviewer 3

The manuscript addressed  characterization of otassium Solubilizing Bacteria and their impact on promotion of maize growth.  

The paper is generally OK. However, the discussion part needs to be substantiated with the relevant explantions to the main context of the manuscript. For example when you present data on K-solubilization please provide adequate explanation on how bacteria can do this, what is the relevant of this trait to the promotion of maize growth. Same for hydrolytic enzymes.

Based on the in vitro results obtained, A comprehensive explanation must be given of of how the bacterial strains promoted maize growth.

Details of comments are attached. 

Reply: Thank you very much esteemed reviewer for good words, all suggestion are incorporated in revised manuscript

 

Reviewer 2 Report

Dear Authors, 

The finding of your manuscript entitled "Polyphasic Characterization of Indigenous Potassium Solubilizing Bacteria and its Efficacy Studies on Maize" is good and you have performed extensive work to evaluate various bacterial strains for multiple biochemical and plant growth promoting characteristics.

However, the writeup of your manuscript is not sound and you need serious attention to improve its writeup.

Some comments are given below but I want to suggest you please revise your manuscript extensively not limited to these comments. 

Methodology

Lines 141-147: The complete detail of the pot experiment is missing (irrigation, sterilized seeds, temperature, experimental conditions, observed attributes observation). 

What is the difference in section 2.5 and 2.8 in methodology? Please combine these sections as these are part of 16S rDNA sequences. 

Section 2.6 Lines 130-140: All the mentioned test are very important to know. Please elaborate their methodology in detail. Biofilm formation is mentioned here but missing in results table/figures and its description.

Line 115-121: Results of morphological and biochemical characteristics are given supplementary material. It will be better to place their methodology part in supplementary method along with their related references. 

Lines 11-12: Two various contrasting temperature are reported here, why? please correct these statements. 

Line123: ARDRA complete form. 

Line 109: Rewrite the sentence.

The methodology related to Table S2 is missing. 

Results and Discussions

Please provide the results and discussions in separate sections. The discussion in current manuscript is very poor and it will be better to provide it in a separate section. 

I will strongly suggest you to move the results of following test from supplementary material into main manuscript (Oxidase, Catalase, Urease, Salt stress tolerance, pH stress tolerance, Drought stress tolerance)    

 

 

 

Author Response

Reviewer 2

The finding of your manuscript entitled "Polyphasic Characterization of Indigenous Potassium Solubilizing Bacteria and its Efficacy Studies on Maize" is good and you have performed extensive work to evaluate various bacterial strains for multiple biochemical and plant growth promoting characteristics. However, the writeup of your manuscript is not sound and you need serious attention to improve its writeup. Some comments are given below but I want to suggest you please revise your manuscript extensively not limited to these comments.

 

Methodology

Lines 141-147: The complete detail of the pot experiment is missing (irrigation, sterilized seeds, temperature, experimental conditions, observed attributes observation).

      Reply: corrected in revised manuscript

 

What is the difference in section 2.5 and 2.8 in methodology? Please combine these sections as these are part of 16S rDNA sequences.

            Reply: Both sections are different since 2.8. study diversity whereas 2.8. deals with molecular identification and phylogenetic construction. Hence we request to keep in the present form for better understating.

 

Section 2.6 Lines 130-140: All the mentioned test are very important to know. Please elaborate their methodology in detail. Biofilm formation is mentioned here but missing in results table/figures and its description.

      Reply: These are standard methodologies hence not expalnined in details. Biofilem formation was presented in table 3.

 

Line 115-121: Results of morphological and biochemical characteristics are given supplementary material. It will be better to place their methodology part in supplementary method along with their related references.

      Reply: we had kept in the same form for better understanding.

 

Lines 11-12: Two various contrasting temperature are reported here, why? please correct these statements.

      Reply: corrected in revised manuscript

 

Line123: ARDRA complete form.

      Reply: corrected in revised manuscript (Amplified ribosomal DNA (rDNA) restriction analysis (ARDRA).

 

Line 109: Rewrite the sentence.

            Reply: corrected in revised manuscript

 

The methodology related to Table S2 is missing.

Reply: corrected in revised manuscript and mentioned in 2.4

 

Results and Discussions

 

Please provide the results and discussions in separate sections. The discussion in current manuscript is very poor and it will be better to provide it in a separate section.

 

I will strongly suggest you to move the results of following test from supplementary material into main manuscript (Oxidase, Catalase, Urease, Salt stress tolerance, pH stress tolerance, Drought stress tolerance)   

Reviewer 3 Report

The manuscript addressed  characterization of otassium Solubilizing Bacteria and their impact on promotion of maize growth.  

The paper is generally OK. However, the discussion part needs to be substantiated with the relevant explantions to the main context of the manuscript. For example when you present data on K-solubilization please provide adequate explanation on how bacteria can do this, what is the relevant of this trait to the promotion of maize growth. Same for hydrolytic enzymes.

Based on the in vitro results obtained, A comprehensive explanation must be given of of how the bacterial strains promoted maize growth.

Details of comments are attached. 

Comments for author File: Comments.pdf

Minor editing of English language required

Author Response

Reviewer 3

The manuscript addressed  characterization of otassium Solubilizing Bacteria and their impact on promotion of maize growth.  

The paper is generally OK. However, the discussion part needs to be substantiated with the relevant explantions to the main context of the manuscript. For example when you present data on K-solubilization please provide adequate explanation on how bacteria can do this, what is the relevant of this trait to the promotion of maize growth. Same for hydrolytic enzymes.

Based on the in vitro results obtained, A comprehensive explanation must be given of of how the bacterial strains promoted maize growth.

Details of comments are attached. 

Reply: Thank you very much esteemed reviewer for good words, all suggestion are incorporated in revised manuscript

Round 2

Reviewer 1 Report

Thank you for the effort you have put into to the manuscript. The manuscript has been greatly improved. However, there are still some problems to be resolved.

 

Line 160-161 Please add data analysis method.

 

In Results, significant differences between treatments were described, but there is no data analysis of these data, such as Line 471-475.

 

After treating maize seeds with KSB, how to confirm the survival of KSB strains in the rhizoshpere of maize?

Author Response

Reviewer responses

Thank you for the effort you have put into to the manuscript. The manuscript has been greatly improved. However, there are still some problems to be resolved.

Reply: Dear esteemed reviewer, thank you for your kind appreciation. We had incorporated all the suggestions in the Ms.

Line 160-161 Please add data analysis method.

Reply: This was added in the Ms.

In Results, significant differences between treatments were described, but there is no data analysis of these data, such as Line 471-475.

Reply: This was added in the Ms.

After treating maize seeds with KSB, how to confirm the survival of KSB strains in the rhizoshpere of maize?

Reply: The result from the pot experiments clearly suggests that KSB strains are increasing plant growth hence this can be concluded that this has ability to survive the maize rhizoshpere. We had also performed field studies which was not included in this Ms. and got the confirmation that KSB population was increased in the soil after crop cycle.

Reviewer 2 Report

NA

 

Author Response

Dear esteemed reviewer, thank you for your kind appreciation. We had incorporated all the suggestions in the Ms.