Microbial Factories and Exploiting Synergies of Bioreactor Technologies to Produce Bioproducts
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Microbial factories and exploiting synergies of bioreactor technologies to produce bioproducts
The manuscript investigated the concept of synergies of bioreactors to produce bioproducts. The authors showed that the waste streams from one bioreactor can be used to drive the production in other bioreactors. The language and general comprehension of the manuscript is fine however, the manuscript fails to give a comprehensive state-of-research about this topic. The past studies about the subject seem lacking in the manuscript. Moreover, the purpose and novelty of this study need to be clearly demonstrated.
Some of the comments to improve the manuscript are as follows:
1. The abstract should be 200 words in a single paragraph. Please follow all the guidelines of the journal.
2. The abstract only summarizes the background/literature. It should comprise of background to highlight the purpose of the study, methods, main findings of the study and conclusions.
3. Line 49-50, “waste streams from one…….”, the authors should give examples from studies from literature with references. Introduction lacks the current state of research about this field.
4. Abstract and introduction lacks how this study is novel from the ones in literature?
5. What were the concentration of the media used in the study?
6. Line 138, please check and correct the formatting of the references.
7. Line 161, “by day 7 the rate of biomass increase was slower”, slower compared to which day? What are the values? How much slower?
8. Please mention all the formulas in the methods sections that were used to calculate the growth kinetics in section 3.1.3.
9. I suppose that section 4.3 bioproducts production can be supported by experiments by authors for the production of materials from the microbial factories. Currently, it this section does not add any new information in the research.
10. Please add a conclusion section in the manuscript.
11. The language of the manuscript is at a sufficient level, nevertheless, I still recommend double check the manuscript to remove all the grammatical errors and typos.
Comments on the Quality of English LanguageThe language of the manuscript is at a sufficient level, nevertheless, I still recommend double check the manuscript to remove all the grammatical errors and typos.
Author Response
see attached file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral comments
The paper requires a very thorough language and grammar check. There are many issues that need to be resolved before the language used in the manuscript has the quality that is expected for a scientific paper. I have indicated some issues in the specific comments below for the first page of the manuscript. Similar problems appear throughout the manuscript.
The results presented in the paper do not bring any major novelty. The calculations should be much better documented (e.g. Table 2 results) and the result interpretation also requires more detailed calculations. If this synergistic type of cultivation is to be used for any practical purpose, the authors should give an idea how much reactor volume would be required to process a quantity of CO2 produced by a single person (referring to application of the technology in a space station, for example).
Specific comments
- Line 16: The first part of this sentence sounds rather strange and needs to be rephrased (‘The diversity of microbes, from bacterial, fungi (e.g. yeast), microalgae, …
- Line 18-19: ‘Synergies can also optimize yields …’ should be ‘Exploiting synergies can also lead to optimized yields …’
- Line 19: You need to be more clear. ‘coupling of microalgae to microalgae cultures’ sounds confusing to me. You should rather write ‘coupling of two different species of microalgae’
- Line 24: I suggest not to use the term ‘Batch-fed’. The bioreactor operation that is described in the paper is not a batch operation where all substrate is dosed at the start of the process, and it is also not a fed-batch operation (the volume of the cultivation is constant here). The operation of the bioreactors described here is in fact the operation of a continuous bioreactor, but with pulse addition of the feed (one pulse per day). I would remove the term ‘batch-fed’ from the paper because it is confusing.
- Line 32: The statement ‘microbial factories are bioreactors with unique microbial cultures …’ sounds rather strange to me. I would rather write ‘Microbial factories are unique microbial cultures exploited in bioreactors …
- Line 33: ‘values chain’ should be ‘value chain’
- Line 36: Sentence ending with the word biochemicals does not have a full stop.
- Table 1: The table caption should appear on the same page as the rest of the table.
- Line 44: ‘making biodegradable materials’ can be replaced by ‘manufacturing biodegradable materials’
- Line 100: The term ‘data dropouts’ should be removed and replaced by ‘missing values’.
- Line 101: The term ‘aberrant data points’ is to be removed and replaced by ‘outliers’
- Table 2: I assume that m (d-1) should be the Greek letter mu that is generally used for growth rate? Calculations to obtain the values shown in this table have to be explained in the methods section!
- Line 193: ‘Statistically differed’ should be ‘statistically different’
- Line 201: ‘stead-state’ does not exist. The correct term is ‘steady state’
- Line 205: You need to add units when you report specific growth rates, not just a number!
- Figure 3: The figure caption needs to be on the same page as the figure itself.
- Line 301: Be more specific – what is it that tends to decrease with increased volume?
Comments on the Quality of English LanguageSee above
Author Response
see attached file
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript investigates the concept of bioreactor synergies. Data from batch cultures of yeast and algae bioreactors are presented and used to calculate production and consumption rates of the waste products. The research topic is interesting, but the manuscript is a very early study and its content was not well organized. No key experimental findings can be found in the Abstract section. The literature review in the Introduction section was not enough, and the novelty of this manuscript was not identified. The Discussion section was unduly dependent on the previous findings rather than the experimental findings in this work. Furthermore, there are a number of grammatical, format errors and poorly organized sentences in the manuscript, which decreased the readability of research contents, and should then be carefully revised. As such, the submitted manuscript did not meet the criteria of the journal.
Comments on the Quality of English LanguageExtensive editing of English language required.
Author Response
see attached file
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe corrected manuscript has answered all of my comments.
Author Response
The reviewer was satisfied with the first revision. Therefore, the second revision fufills with this reviewer's concerns.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral comments
The paper is easier to follow compared to the first version. Some minor specific comments are given below.
In the discussion there is a lot of focus on the production of specific products, the consumption of CO2 by microalgae as well as the production of O2 by the microalgae. However, it would also be of interest to hear the author’s opinion about what to do with the biomass that is produced during the cultivations (yeast and microalgae).
Specific comments
- Line 58: I suggest to write ’pure microbial cultures’ instead of ‘microbial cultures’
- Line 61-62: Replace ‘settlement’ by ‘sedimentation’. The word settlement has a very different meaning.
- Table 3: It would be best if the Table caption starts on a new page
- Line 122: ‘with filled’ should be ‘filled with’
- Line 179: ‘Equation 3 was used for O2 production rate…’ should be ‘Equation 3 was used for calculating the O2 production rate …’
- Line 214: ‘pH increased’
- Line 224: ‘pulsed medium’ should be ‘pulsed medium addition’ (also line 243)
- Line 267: ‘the result dilution by the lower …’ should be ‘the result of dilution due to the lower …’
- Line 274: ‘in biomass’ should be ‘in biomass concentration
- Line 290: Remove the s at the end of fours!
- Line 303: ‘the main DO’ should be ‘on the main DO’
- Line 309: ‘high concentrations CO2’ should be ‘high concentrations of CO2’
- Table 5: Keep the table on a single page, not spread out over two pages!
- Line 363: What is the background for writing ‘For 50 mg of yeast, 50 mg of glucose is needed’? The stoichiometry (reality) is much more complicated compared to what is shown on line 361. Some C is used for energy generation, some for biomass formation and maybe even product formation. And there is also maintenance which is not really considered. The calculation on the next line seems to assume that there is a steady state situation. It would be good with some more clarification.
- Figure 4: There is a typo in the figure, part b (cylindrical)
- Line 450: I would replace ‘foodstuffs’ by ‘food ingredients’
Comments on the Quality of English LanguageFew suggestions for changes in the specific comments above.
Author Response
See attached file or the reply below in the Review Report Form.
Author Response File: Author Response.pdf
