Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plants

Round 1

Reviewer 1 Report

Review comments on:

Lee et al., 

Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plant

Major comments.

This paper describes on plant growth promotion effect, silicate and phosphate salts dissolution, and organic acids, IAA and GA production by an Enterobacter ludwigii isolate. 

 My major concern is about the experiment for its growth promotion effect. Line 153, they used bacterial broth diluted 10 times in distilled water, as an inoculant. They prepared a control with distilled water only. Don't we need to consider the effect of culture media brought into the test? 

Minor comments.

L20 16"S"

L21 and elsewhere, "ascetic acid"

L45-46, do not italicize "sp."

L71 and elsewhere, cm(-3) is used for volume, but ml or microliter would be better. 

L71, 10 g cm(-3): glucose can not dissolve at this high concentration

L107 "Briefly," should be "In brief,"

L109 "onto the peptide using Sep-Pak": Sep-Pak is just a C18 cartridge without peptide.

L118 "methanol methyl esters" ???

L124 GA standard was added: What is this GA standard?

L130 EtOAc: this would be ethanol acetate.

L137 2.7.1: This section is not necessary

L146 "horicole": What is this?

L168 ICP "machine": is this ICP-MS or something else?

Figure 1 does not make any sense, only showing one plant each.

Table 1 does not provide meaningful information without identification of the isolates.

Fig. 2 caption: Information about the primers and BLAST is written in the text, rather, that for constructing the tree should be written.

Section 3.3 and Figure 3 are not necessary. Especially Fig 3A is a growth curve, but it does not have 0 time data. Fig 3C does not seem to have SD bars?

L240 "ug" must be microgram.

L240 113.816 ug/ml, and Tables 2 and 3. The authors must consider well on their technical accuracy and significant digits for these measurements. 

Fig 4,5, Table 2,3. The authors must learn about statistics. Do not use Student's t-test for more than 2 groups. 

L316, 326 "cell extract": The extract was used, instead of living cells?

The Discussion section includes many repetition of the results, which makes itself very boring. 

Author Response

We would like to resubmit our revised manuscript (ID: agronomy- 453324) entitled ‘Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plant’. In this revised manuscript we have attempted to address all the issues raised by reviewers and editors. We modified the manuscript as per the comments and suggestions of the reviewers and editor.  Authors’ responses to the comments are highlighted with red color in response letter as well as in manuscript.  The green highlight in the manuscript is the revised content of the first major revision. According to the suggestion, we have submitted the manuscript in track change function.  We have included the new data related to ammonia production by microbes and growth promoting characteristics  of  rice mutant  Waito-C.  According to reviewer suggestion we have removed Figure 1B, Table 1, Figure 3, Section 2.7.1, Section 3.3. and included new Table 1, and Fig 1B. The conclusion section 5 is added and some information were modified in discussion section. The responses to the comments are addressed in the attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

The presented manuscript of „Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plant“ describes complicated series of laboratory experiments on relation among bacteria, fertilizer and plant. The manuscript shows the innate ability of the strain E. ludwigii GAK2 to solubilize silicate and phosphate that produce some organic acids and phytophormones (IAA and GA). The authors found, that E. ludwigii GAK2 might be employed as an efficient inoculant for plants as a silicon and phosphate biofertilizer to promote plant growth. Result can help on agricultural land containing abundant amounts of insoluble silicate and phosphate. The content of the manuscript is therefore very important for current agricultural research.

The manuscript is prepared on high level. All necessary attributes for publication in scientific journal are catched.

My recommendation:

The part of methodology is very comlicated, but I do not how to recomend to describe the steps of the experiment more comprehensive. Despite, please, could authors write more about 2.3.2. Germination Promotion Test on Rice. Present text describe the germination test quite superficially. Please, include what characteristics were detected, atc.

It will be probably more clear, if authors will presented statistical results according the 2.9. Statistical Procedures…. So, instead term of „Student’s t-test“ they will use name of statistical method „LSD method“.

Figure 3: all the three graphs A, B, and C do not correspond with a title of the Figure. In addition, bars represented SD are bad editable around points.

Table 2: I suposed, that letters in the column of F.SW (g.plant-1) are wrong/confusing

Author Response

We would like to resubmit our revised manuscript (ID: agronomy- 453324) entitled ‘Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plant’. In this revised manuscript we have attempted to address all the issues raised by reviewers and editors. We modified the manuscript as per the comments and suggestions of the reviewers and editor.  Authors’ responses to the comments are highlighted with red color in response letter as well as in manuscript.  The green highlight in the manuscript is the revised content of first major revision. According to the suggestion we have submitted the manuscript in track change function.  We have included the new data related to ammonia production by microbes and growth promoting characteristics  of  rice mutant  Waito-C.  According to reviewer suggestion we have removed Figure 1B, Table 1, Figure 3, Section 2.7.1, Section 3.3. and included new Table 1, and Fig 1B. The conclusion section 5 is added and some information were modified in discussion section. The responses to the comments are listed in the attached file:

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Review comments.

Only minor comments.

L86 1 ml<3>

L111 Biochemical Analysis

L113 5 cm3 -> 5 mL

L118 Optimal density -> optical density

L145 5 mM H2SO4, 0.6 ml min(-1)

L156 In brief,

L158 GA1 and GA3 standard was added: I guess they must be standards labelled with isotopes. Please describe what are they exactly.

L261-262 I guess they used T-test here, not LSD.

L267-269 The strain is registered.... : This sentence appeared in L252. So delete this.

Fig 3. I don't think statistics are necessary here to describe the different levels of organic acid production.

Fig. 4. Again statistics is not necessary here. The description in L383-384 is not necessary as well. 

L385 The unit is weird. 1.74 100ml-1? is it 0.174 u<micro>g/L?

Fig4 caption, (A) gibberellin

L454 No italic "GAK2"

L456 Phytohormones mitigate...

L532 might have led to...

Figures are low resolution in my PDF. Please check quality.

Reference 23-27 Italicize species names.

The reference list should be checked for format, such as Journal name abbreviations.

Author Response

We would like to resubmit our revised manuscript (ID: agronomy- 453324) entitled ‘Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plant’. We would like to thank all the reviewers and editor for their comments on the manuscript. In this revised manuscript we have tried our best to address all the comments and concern. The manuscript has been changed according to comments and suggestion of reviewer and editor. The addition and or changes of the manuscript are in both track and untracked mode and highlighted with red with a yellow background.

Author Response File: Author Response.docx