Effects of CO2 Aeration and Light Supply on the Growth and Lipid Production of a Locally Isolated Microalga, Chlorella variabilis RSM09
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDespite the interesting topic of using microalgae as a source for the production of fatty acids, the paper is a typical description of research results. Unfortunately, the authors were not tempted to carry out a comparison of the results obtained with literature data indicating the significance and innovativeness of the results. It would also be worthwhile to add a short chapter indicating the potential of the obtained studies as alternative sources of fatty acids with different applicability.
Furthermore, the paper requires some additions and corrections. Below are some detailed suggestions:
1. The abstract should be reworded to have more impact and to highlight the results. In my opinion, the abstract contains too much detail and inconsistencies in tense and grammar.
2. It is generally better to use consistent tenses in scientific texts. For example, instead of ‘was about 2.91’ ‘was about 2.91’. This adds a bit more formality to the tone.
Next - ‘Follow by’ should be ‘followed by’. Minor grammatical corrections such as these can improve readability.
3. The analysed range of CO2 amounts from 0.03 to 50% is surprising. The paper lacks an explanation on what basis this range of CO2 quantities was chosen.
4. Please examine Figures 6 and 8, as the error bars are not marked on all curves.
5. The methodology lacks inofromation on the number of repetitions and what was taken as a control sample.
6. In the summary, we find information about the composition of the extracted fatty acids, but neither the methodology nor the description of the test results mention this.
Comments on the Quality of English Language
It is generally better to use consistent tenses in scientific texts. For example, instead of ‘was about 2.91’ ‘was about 2.91’. This adds a bit more formality to the tone.
Next - ‘Follow by’ should be ‘followed by’. Minor grammatical corrections such as these can improve readability.
Author Response
Dear reviewer,
Kindly refer to the attached file for your review.
Best Regards,
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsA. Chantarasari and S. Ungwiwatkul submitted a manuscript entitled ‘Effects of CO2 Aeration and Light Supply on the Growth and Lipid Production of a Locally Isolated Microalga, Chlorella variabilis RSM09’ to be considered for its publication in the journal Applied Sciences by MDPI. Thus, after carefully reading the manuscript, I found that it is interesting and hence publishable practically in its present form in the AS journal due to various reasons. For instance, I found it fits into the scope of the journal, meeting well its standards. Enough novelty/originality come from the work. Indeed, I consider its main strength is that Authors found the conditions in which the studied alga growth better producing greater amounts of lipids. These results may be useful for producing biodiesel from local (Rayong, TH) resources. The paper is well written and easy to read. Introduction shows well the context of the work. References cited are enough and pertinent. Materials and methods section is described in detail. Results are well discussed. Figures, pictures, graphics, and plots show accurate and concise information. Conclusions are supported by results. Thus, my unique suggestion is to make a grammar/style revision to enhance the manuscript to avoid sentences like the first one from conclusions paragraph ‘The present study investigated’. Can a study investigate something?
Author Response
Dear reviewer,
Kindly refer to the attached file for your review.
Best Regards,
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
The manuscript presents a theme of significant scientific relevance. However, I have only a few comments.
I have listed my comments below:
1. I suggest including the graphical abstract, this could increase the visibility of the article.
2. Why do the authors use lux as the measurement unit and not micro Einstein for light intensity?
3. The description of C. variabilis is not italicized in several parts of the manuscript. I recommend the authors review it.
4. The collection of microalgae occurred in a eutrophic region. Did the authors assess the presence of toxins?
5. I recommend that authors indicate in Figure 1 which software GPS was used.
6. What software was used to create Figures 2 and 3?
7. In Figures 4 and 5 the representation of carbon dioxide is not correct.
8. In my opinion, Figures 4-9 need adjustment. For this, I recommend using more suitable software such as GraphPad Prism (any version).
9. Why did the authors not include chromatogram analysis?
Author Response
Dear reviewer,
Kindly refer to the attached file for your review.
Best Regards,
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe novelty and significance of this work should be made more explicit, especially in the abstract and conclusion sections. There is no sufficient discussion of the results obtained. After major revisions, I recommended publishing this work in Applied Sciences.
Detailed remarks:
P1, L12-13: Explain how the variables used for CO2 concentration, light intensity and photoperiod were determined.
P1 L14: How the best growing conditions were determined. Was it based on biomass production or lipid production? This issue should be explained.
The introduction needs to be adapted to align with the set hypotheses and objectives of the research.
P2 L80-83: Detailed information on cultivation should be given. How many replications were the trials prepared? It should be explained.
How was it decided to terminate the Microalgal Growth Period? It should be explained.
Were the biomasses dried before lipid extraction and fatty acid analysis? Or were they used directly? It should be explained. If drying was applied, the conditions should be given.
It is an important deficiency that statistical analyses were not planned in the study. The method and program used in analyses should be explained in the method section.
Are lipid content and fatty acid analyzes sufficient to determine the quality of microalga to be used in biodiesel production? It should be explained.
The Results and Discussion section contains many tables, but the results lack in-depth discussion. Explain the trends observed in your results within this section. Provide more interpretation.
Author Response
Dear reviewer,
Kindly refer to the attached file for your review.
Best Regards,
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors made the suggested changes. In this form the work looks much better. A particularly big improvement can be seen in the quality of the accompanying figures.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
I appreciate your response.
Best regards.
Reviewer 4 Report
Comments and Suggestions for AuthorsIn my opinion, the comments indicated in the previous review have been taken into account to a sufficient extent.
The article can be accepted for publication in Applied Sciences.
