Natural Substrates and Culture Conditions to Produce Pigments from Potential Microbes in Submerged Fermentation

Round 1

Reviewer 1 Report

Manuscript Number: fermentation-1891340

Title: Natural substrates and culture conditions to produce pigments from potential microbes in submerged fermentation

 

Dear Editor,

This manuscript provides a study of the aspects of potential pigmented microbial diversity in submerged fermentation with natural substrates and culture conditions. Few studies on this subject was reported in literature and the data are well presented and discussed. This manuscript is very interesting for publication in Fermentation.

 

Some considerations:

1. The abstract needs to bring more specific information about the novelty of the review itself.
2. Line 56-64: No references in this section?
3. Table 1. Improve application description. It's generic. Example: bioactive?
4. Table 2. Improve substrate description. Since the article's differential is its approach to low-cost substrates, it is necessary to better specify the description of this item in the table. Example: Fruit waste. Which?
5. Table 2: What is the concentration of each substrate specifically in the culture medium? This information is very useful in a review approach because it will help readers make a comparison of studies. Example: Fruit waste 1%, 2%? This for all substrates covered in this table. Same comment for table 3.
6. I missed 1 or 2 paragraphs describing the economic issue of pigments, since the theme is to reduce production costs with natural substrates. This comment could come in perspective.

Author Response

Please see the attachment 

Author Response File: Author Response.docx

Reviewer 2 Report

The review from Chatragadda Ramesh et al. gave an overview of pigments production from potential microbes in submerged fermentation, which could provide some useful information for natural pigment production. However, there are several concerns related to the quality and contents of the article. 

#1 The contents related to microalgae are far from the state-of-the-art status. Quite limited information is provided in this article. In the abstract, the authors do not mention microalgae at all. In sections 1, 2, 3, and 5, the authors include microalgae but in sections 4, 6,9 nothing about microalgae, which is not fine since microalgae are so important in these sections, for instance in climate change. 

#2 Line 32, 33, 'bacteria [1,2], fungi [3–6], yeast [7–10], cyanobacteria [11], and microalgae [12,13]' if you separate cyanobacteria and microalgae, you need to give information also for cyanobacteria in relevant sections. I don't find any information. In addition, Spirulina also belongs to cyanobacteria. And also think about your topic 'submerged fermentation'. Can you call microalgae production fermentation? 

#3 Line 86 'food and drug applications', the authors do not talk about one of the most important things in the article, the regulations. 

#4 What is the scientific meaning to provide Figure 1?

#5 Line 'Xianthophyllomyces dendrorhous' why list a specific species together with others like yeast and microalgae. 

#6 Table 2, 'microalgae' why only show results with wastewater? What are the current production media and what are the normal production yields?

#7 There is not so much scientific meaning for production rate in mg/L, people care more about productivity and production yield. I don't find any numbers in the article about the total yield of specific pigments and values in the market.

#8 Line 247&248, 'easiest, rapid, effective, cheap, and time-saving method to isolate and purify pigment molecules over non-pigmented compounds’， tell me the cost numbers, evidence, comparisons with other techniques, and references to convince me of your statement. Why TLC is the easiest et al. 

#9 Line 277, is Galleria mellonella widely used or accepted?

#10 section 9. Role of pigmented microbes in climate change. When you talk about CO2, it is unacceptable to not talk about microalgae.  

#11 Rewrite the Future directions to make them clearer. 

Author Response

Please see the attachment 

Author Response File: Author Response.docx

Reviewer 3 Report

The review is very interesting. I added some comments along the manuscript, regarding better formating of table, some techniques that are mentioned during the manuscript that need more clarification. In addition, please compare submerged and solid state cultivation in a small paragraph, just to inform the readers. Congratulations on your manuscript!

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors made proper revisions for most of my comments. However, the authors have to address the following comments. 

#7 There is not so much scientific meaning for production rate in mg/L, people care more about productivity and production yield. I don't find any numbers in the article about the total yield of specific pigments and values in the market.

Authors reply: The production rate values are given based on the literature. Hence, we could not convert them into market level values.

There are many resources for specific pigments yield and revenue for instance carotenoid. A review paper has to give as many as numbers found from references. 

#8 Line 247&248, 'easiest, rapid, effective, cheap, and time-saving method to isolate and purify pigment molecules over non-pigmented compounds’， tell me the cost numbers, evidence, comparisons with other techniques, and references to convince me of your statement. Why TLC is the easiest et al. 

Authors reply: TLC is cheaper compared to other chromatographic techniques such as high-performance liquid chromatography (HPLC) and High-performance thin-layer chromatography (HPTLC), which are basically costly instruments that require more maintenance and costly consumables to process samples. Hence, TLC stands as a cheapest and efficient method to purify pigments in the initial stage of experimentation.

DO NOT state as cheapest et al. if you cannot give specific numbers for cost with evidence. That is not true!!! Does not convince me at all. Be careful with strong statements.