Single-Chamber Electrofermentation of Rumen Fluid Increases Microbial Biomass and Volatile Fatty Acid Production without Major Changes in Diversity

Round 1

Reviewer 1 Report

The manuscript investigated the effects of external electric potential (0.4 and 0.9V) applied in a single-chamber EF using a rumen microorganism inoculum and Rhoades grass pasture as substrate on dry matter digestively (DMD), biomass, bacterial communities, and VFA production.

1.      There is a complex and dynamic microbial ecology in the ruminal environment, with strict and facultative anaerobes, such as bacteria, fungal, and protozoa which change over time and feeding. Does the application of external electric potential affect rumen fungal community compositions？

2.      Why are individual differences so great in principal coordinate analysis (PCoA) plots of the bacterial community compositions in the rumen fluid?

3.      Upload the sequence of bacterial community compositions of rumen fluid.

4.      There is no significant difference in Table 1, and lowercase letters are not required.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

This study aimed to evaluate the effects of a single chamber EF application (0.4 vs 0.9 V) for 6, 12, or 24 h, on rumen fluid, the resulting microbial biomass, dry matter digestibility (DMD), VFA production, NADH/NAD ratio, and composition of its bacterial communities. It is an interesting study and within the scope of the Journal. I have some comments to improve this manuscript.

Line 169: How many replicates the author did for these procedures.

Line 192-200: Why the authors did not run the two ways ANOVA to test the treatment effect (three levels: control, 0.4 V. and 0.98 V), the time effect ( at 6, 12, and 24 hr), and the interaction.

Line 253: Please delete as expected.

Line 409-426: try to reduce the conclusion section (or edit this heading to be conclusion and challenges)

Line 418-426: It should be under a subtitle of limitations and challenges.

Figure 1: Please add more description for this figure.

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Thank you very much for your response. Your manuscript was greatly improved after addressing the comments in the first round of reviewing. I still recommend Two-Way ANOVA to represent your results (it is upon the editorial decision). Otherwise, please integrate your response in the statistical section.

Author Response

Comments for reviewer.

Thanks for these suggestions; following your recommendations, we tried our best to address every one of them. 

To improve the statistical section

• We have edited the text incorporating what we use for data analysis by two-way ANOVA and comparative means using a post hoc Tukey test in lines 204-205, highlighted in yellow.

To improve the results sections 

• We have edited the text and incorporated the results of two-way ANOVA analysis for the measurement of the parameters in our manuscript: 

Lines 220-222, for Biomass results.

Lines 230-231 for DMD results.

Lines 246-249 for VFA results.

Lines 266-268 for pH results.

Lines 272-276 for NAD results. 

And Lines 279-280 for NADH and NADH/NAD results.

To improve Figures 2 and 3

• We have edited Figures 2 and 3, incorporating the information of two-way ANOVA analysis results and their information in figure captions. These changes in Figure 2 and 3 captions are shown in lines 236-240 and 280-285, respectively.