Modeling and Optimal Control of an Electro-Fermentation Process within a Batch Culture

Round 1

Reviewer 1 Report

The authors present an excellently written manuscript. I would recommend publishing as it is.

Author Response

We wish to thank Reviewer 1 for the careful reading of our manuscript and for  the positive comments.

Reviewer 2 Report

In my opinion, manusript ID processes-1597685 entitled “Modeling and optimal control of an electro-fermentation process within a batch culture” concerns an interesting issue related to the modeling and optimization of electro-fermentation processes. Electro-fermentation is currently seen as a method to improve the efficiency of conventional techniques by increasing the growth of fermenting bacteria and their metabolic efficiency.

In the manuscript, the authors attempted to propose a model describing the transition between the two metabolic behaviors in response to different electrode potentials. Based on this model Authors try to study how to control the fermentation in order to maximize the production of one of the rising fermentation products.

In my opinion, the manuscript brings new information in the field of electo-fermentation and may be of interest to both other researchers and teams working on the implementation of this type of technological solutions.

In my opinion, the manuscript requires some additions and explanations:

1. Abstract must be completed. Abstract - The author fails to emphasize the novelty and significance of the study. Authors should clearly formulate the aim of the research An abstract summarizes, usually in one paragraph of 200-300 words or less, the major aspects of the entire paper in a prescribed sequence that includes: i) the overall purpose of the study and the research problem (s) you investigated; ii) the basic design of the study; iii) major findings or trends found as a result of your analysis; and, iv) a brief summary of your interpretations, recommendations as a way forward and conclusions.
2. Graphical abstract will be very useful for readers to understanding Authors intention and aim of study.
3. Please provide more keywords related to the content of the manuscript.
4. In my opinion, the Introduction provides not enough good background to this overview manuscript. The authors should provide more information on the attempts to optimize fermentation processes so far. I believe that the paragraph on electro-stimulation of fermentation processes should be developed and their development should be presented using various techniques, not only cells: https://doi.org/10.3390/fermentation6030092, https://doi.org/10.3390/pr10010045, https://doi.org/10.3390/fermentation7040291, https://doi.org/10.3390/fermentation7010012.
5. Research novelty should be better highlighted.
6. What input data were the authors based on when developing the model. Do the adopted coefficients come from the literature data or were they obtained during own research? Has the model developed by the authors been verified and what is its credibility and usefulness? This must be thoroughly discussed and explained in the body of the manuscript.
7. In my opinion, optimization models should be developed on reliable input data. Please indicate the source of this data.
8. Expand the Discussion in the manuscript. The obtained results should be presented against the results obtained by other researchers. Trying to discuss it as it stands is not enough.
9. Please describe in more detail the credibility, fit, usefulness and practical implementation of the developed model.
10. How it can be used in research or operational practice.
11. The conclusions are very general and do not sum up the optimization work done by the authors.

Author Response

Please find our reply by the attached file. 

Author Response File: Author Response.pdf

Reviewer 3 Report

In this manuscript, the authors developed a mathematical model to predict the optimum operation of an electro-fermentation bioprocess by balancing the metabolic activities between classical fermentation and electro-fermentation metabolism. Overall, the work is valid, important and the taken approach and steps seem logical. However, from the request for review and abstract, the pure mathematical nature of this article was not obvious to me. And while I am an expert in microbial bioelectrochemical processes and microbial physiology, I am not able to provide a deep critical review of the core mathematical content of this manuscript. If the authors had applied their model to a real electro-fermentation process to check validity and determine limitations, I could judge more thoroughly on the soundness of this model. A validation with a real process, would also highlight the value of this model to practical researchers in this field. However, as it is now, I can only state that the manuscript is well written in a clear and well understandable English and that all thoughts and arguments follow a clear logic. If the mathematics is correct, will have to be judged by a different reviewer.

Author Response

Please find our reply by the attached file. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Manuscript has been improved in line with Reviewer comments. In my opinion manuscript can be publish in current form.