Bioconversion of Agro-Residues into Microbial Oil-Based Oleochemicals Employing Packed Bed Bioreactor

Round 1

Reviewer 1 Report

Researchers systematically evaluated the microbial oil production by ole-aginous fungal strains on Cakes from palm kernel. The manuscript is well organized and most of characterization is well explained. However, it is not ready to be published until the following concerns being properly addressed. 

1. In Figure 1, why C. echinulate group produced two or three times more microbial oil than the other two M. ramanniana groups?

2. Why was PKC chosen from four agro-residues for Screening of fungal strains and later experiments?

3. In the “effect of temperature” section, it is not solid to say that “temperature affected lipid production mainly due to its impact on the moisture content of the substrate”. Lipid production should be influenced by multiple parameters besides the moisture.

4. How the ratio of saturated to unsaturated lipids (RSU) be determined? What is the benefit of high or low RSU number?

5. In Figure 3 a-b, it is hard to read the data for 60% moisture content. Plotting needs to be improved.

6. Is there any literatures or experimental evidence to support the statement in lines 372-373 that “This was possibly related to the lignin-rich and protein-low content of PPF”?

Author Response

The authors have included the anwers in a word file.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is very interesting, well written, and well organized, and represents some advancement over the actual state-of-the-art. The ways and means are well described as well as the obtained results which are thoroughly discussed and conclusions are well-drawn. The paper is also supported by some literature review. However, to make for a stronger paper, I suggest that the authors should cite and discuss the following relevant papers, which could be used as benchmarks towards the proposed approach for example 'Advances in solid state fermentation for bioconversion of agriculture wastes to value added products: opportunities and challenges (https://doi.org/10.1016/j.biortech.2021.126065) and A comprehensive review on valorization of agro food industrial residues by solid state fermentation.  (https://doi.org/10.3390/foods10050927)

A comprehensive review on valorization of agro-food industrial residues by solid-state fermentation

 

 

Author Response

The authors have included the anwers in a word file.

Author Response File: Author Response.docx

Reviewer 3 Report

At first glance, the manuscript appears to be very rich in arguments and experiments conducted. However, as you read the manuscript, the impression I got is that there is a lot of confusion in the topics covered

The introduction requires careful review, the level of English makes it difficult to understand key concepts of the manuscript.

In the introduction, I would insert the state of the art in the use of Mortierella sp. in the valorisation of lignocellulosic materials, since it has been extensively studied.

section 3.1 has only the description of the results, but there is no discussion.

In general, the results are well described, but there is a lack of discussions aimed at giving a reason to the results obtained. In fact, I hardly ever see a comparison with data in scientific literature.

In section 3.2 I see the figure referring to the results of C. echinulata, M. ramanniana, and M. ramanniana, but in this paragraph the authors talk about growth results for T. elegans and M. isabellina... but where are these results? and even here, there is no discussion of the data obtained.

All the manuscript has the same problem: many experiments, no explanations/discussion/comparisons with scientific literature, and I was amazed that there are no statistical analysis in all experiments. Moreover, the standard deviations in the figures seem very small to me, as if there were never any differences between the replicates (which is strange under the conditions described).

The tables are missing of standard errors, which is a serious mistake for a scientific paper.

I would reorganize the whole manuscript, maybe reducing some experiments and focusing on the main results obtained (and of course adding some statistical description and discussions of the data...)

Author Response

The authors have included the anwers in a word file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All my questions are well answered. 

One comment for the revised manuscript: the newly added" Different letters indicate statistically significant differences (p<0.05)" is confusing. What is the specific statistical difference between each data? How does author define "the significant differences"? In addition, author used the letters (like a, b, c...) to differentiate the sub graphs so it is better to use other set of characters or colors to represent information such as the statistical difference.

Author Response

The authors would like to thank the reviewer for the comments.

The authors are sorry for this misleading. The letters that refer to the statistical analysis are omitted from the Figures (apart from Figure 7) and a related text with a comprehensive description is included in lines 292-295, 378-381, 386-389, 447-451, 459-466, 593-600, 604-605 of the revised manuscript.

Reviewer 3 Report

The authors have improved the whole structure of the article and the quality of english.

Now in most of the paragraphs there are discussion points. However, there is still no discussion or data explanation in some paragraphs (check the file attached).

Descriptive statistics have been added to the article, but I'm surprised that an important result such as the fatty acid analysis was done without replicates. In this way the data are not statistically relevant. 

The authors said "The majority of scientific studies that report the composition of microbial oil and oils in general, don’t give standard deviations" and this is in part true, but the n of the experiments should be at least 3 or higher for a relevant scientific paper. 

Anyway, I have reported some notes to the article in the attached file. English requires another revision, and i would check also the reference style.

Comments for author File: Comments.pdf

Author Response

The authors have encolsed a word file.

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

The article after the second revision has been improved.

The authors have fully answered my requests/questions and now I think the article is suitable for publication.

I would just take a look at the quality of the English, which could still be a little bit improved in some passages.