Effect of Replacing Fish Meal Using Fermented Soybean Meal on Growth Performance, Intestine Bacterial Diversity, and Key Gene Expression of Largemouth Bass (Micropterus salmoides)
and Hanjie Ying 1,2Round 1
Reviewer 1 Report
In this work, the authors discuss the effects of replacing fish meal using fermented soybean meal on growth performance, intestine bacterial diversity, and key gene expression of largemouth bass (Micropterus salmoides). The topic is interesting and the manuscript has a potential from a scientific point of view. However, there are a few points that require the authors’ attention.
1. Line 42: In my opinion, economic values should be expressed in universally understandable currency, e.g. USD or Euros.
2. Line 45: “However” is usually used to introduce a statement that contrasts the previous one. In this case, it is irrelevant. Just say that all previous factors affect negatively the fish growth (as expected). Also, please explain in brief what are the negative effects of these elements.
3. Lines 47: Either state the species used (preferably) or “lactic acid bacteria”.
4. Lines 54-56: A few more information about perch are needed. Does it eat only fish meal? Is it nutritious and preferred? How many aquacultures are there? What is the the real cost of feeding perch (in brief)? These are important information in order to support the goal of this study.
5. Lines 76-77: Add the origin of each material used (manufacturer, country).
6. Lines 78-79: Each culture was directly inoculated in soybean meal? Did the authors perform not perform cell harvesting (centrifugation)?
7. Line 109: Please state how many fish were present per tank.
8. Lines 110: How much food was applied per fish each time?
9. Subsections 2.6, 2.7 and 2.8. Please provide references.
10. High repetition rate was detected in both subsections 2.10 and 2.11. Please edit accordingly and provide suitable references.
11. Table 2: Please add a separate column with all percentage changes noticed after fermentation.
12. Line 291: Please provide full descriptions for these parameters.
13. Lines 350-351: Please explain the importance of this finding (if any) on the nutritional value of the fish. The same applies for the intestines (next paragraph).
14. Most importantly, and in correlation to my previous comment, it is not clear at any subsection the effect of the FSBM on the nutritional value of the fish. I believe after every subsection, the authors should refer to that matter explicitly. Alternatively, the authors could create a new paragraph taking into account all changes on the fish (growth, physiological, biochemical, microbial, etc) and the potential outcome on the nutritional and commercial value of the fish. This must be the main goal (and novelty) of the manuscript, as growth evaluation has already been performed by other researchers (line 58).
15. In the conclusion paragraph, the authors should highlight the importance of their findings. The picture given here is rather general.
Moderate English editing is required.
Author Response
Dear Editor and Reviewer：
The response to these comments can be found in the attachment file (Please see the attachment).
Best regards,
Yafan
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This article deals with an interesting question about feeding fish and about useful supplements in the fish diet. The article has a huge amount of experimental data, but some of it is very questionable. For example, in the abstract and in the conclusions, the authors say that Lactobacillus, Yeast, and Bacillus ferment the soy meal but in Materials and Methods, the strains used are B. amyloliquefaciens, S. thermophilus, and C. jadinii, and there are no lactobacilli.
Other remarks:
Abstract, line 29: Edit the sentence "expression levels of SOD1, SOD2, and SOD3 in 30% FSBM treatments were not lower than those in the control group." Questions arise: were they higher? Or were they equal?
Materials and methods: to indicate the origin of the bacteria strains, number in the collection, microbial collection, city, and country.
Line 80: 1*105 g-1 is not the correct unit for the number of bacteria, the correct one is 1 x 10 5 CFU/g.
Line 198: Question: Why did you use the sample without reverse transcriptase as the positive control?
The legend in Figure 2 has some ambiguities, for example, the indicated red dotted line is missing.
Figure 4 is not readable even at 200% magnification, either enlarge the text or put it in supplements.
Line 513: How do the plant secondary metabolites affect the fish's health? Why is this analysis important?
The article is written in understandable English, although it needs editing.
Author Response
Dear Editor and Reviewer：
The response to these comments can be found in the attachment file (Please see the attachment).
Best regards,
Yafan
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed my comments.
Minor spelling issues.
Reviewer 2 Report
The paper is substantially improved and could be published in its current form.
Good English, no doubt.
