The Effects of Different LED Lights on the Main Nutritional Compositions of Isochrysis zhanjiangensis
Round 1
Reviewer 1 Report
The manuscript focused on the effect of light quality on growth, fatty acids, proteins and carbohydrates of Isochrysis zhanjiangensis. Seven different light colors were tested, being red, orange, green, blue, purple, white and simulated sunlight.
The subject is worthy of investigation and within the scope of Fishes, under the Nutrition and Feeding section. This manuscript was submitted to the special Issue "Feeding and Nutrition of Bivalves". I would recommend to focus the introduction and conclusion on the use of this microalga to feed bivalves, not on its biotechnological applications.
The manuscript is straightforward and well written. However, the manuscript lacks novelty as similar studies for the same species are available and were not cited (e.g. https://doi.org/10.3390/jmse10111752). Moreover, few studies using Isochrysis were referenced.
Please, find below my specific comments:
Lines 11-14: Please rephrase the sentence "To elucidate the effect of light quality on the main nutritional compositions of Isochrysis zhanjiangensis, the growth, fatty acid composition, soluble carbohydrate and soluble protein content of I. zhanjiangensis under different light qualities (red light, orange light, green light, blue light, purple light, simulated sunlight, and white light) were studied." 1. You already mention "light quality on Isochrysis zhanjiangensis" so there is no need to repeat at the end of the sentence. 2. No need to repeat "light" every time.
Line 15: Please, use the actual p value throughout the manuscript.
Line 48: Check Euophthalmos... maybe Eustigmatos?
Lines 54-58: These two sentences sound redundant, merge it.
Lines 62-63: No need to repeat light every time.
Line 68: You mention Fig 1B first... so it should be renamed as 1A instead.
Section 2.1: What is the distance between the different light sources and the experimental units? The distance was the same? The energy content differs for each wavelength, did you measured the incident light/energy reaching each treatment? Each treatment was composed of six experimental units?
Lines 80-81: No need to repeat light every time.
Section 2.2.1: State the salinity, initial pH and cell density. Was the centrifuge refrigerated, if so, state the temperature. Correct rpm.min-1 as rpm means 'revolutions per minute'.
Line 106: All six replicates were measured or were pooled? Not clear.
Line 117: State the ultrasound frequency employed.
Line 133: State that nonadecanoic acid is C19:0, as you mention C19:0 on line 143.
There is no Statistical Analysis section? You mention statistical analysis in the abstract...
Section 3 in general: Please state the actual p value.
Figure 2b: The bars are colored, you mention the LED colors in the X axis, so there is no need for a color legend.
Lines 175-176: True, but the difference is less than 4%... despite being statistically different, does it make a difference in practice? You performed the experiment only once and using the same mother culture. If you repeat the experiment over time, are you sure that you have the same result? You don't mention if each treatment was light adapted before the actual experiment, please report.
Figure 3: Keep consistency between figures. Figure 2 was colored, this one is B&W and you used patterns for each treatment. You didn't measure protein and carbohydrates, but protein as BSA equivalent and carbohydrate as glucose equivalent.
Line 199: Correct "Sirisuk et al. found that [23]" to "Sirisuk et al. [23] found that".
Lines 205-206: Is there a reference for that statement?
line 212: There is no reference specifically to bivalves? [27] is for flounder.
Lines 218-221: Zhang et al. [31] did not employed Isochrysis, please check.
Line 237: You mention growth rate, but you didn't measured it.
Line 240: There is no reference 42, check the references.
Line 243: You have measured cell density, not biomass (i.e. dry weight).
Line 252: Proliferation rate?
Line 261: There is no reference 44, check the references.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript “The effects of LED light quality on the main nutritional compositions of Isochrysis zhanjiangensis” reports on the influence of light conditions on microalgae growth and nutritional composition with regards to the fatty acid, protein and carbohydrate contents.
The study is very simple but well-planned and the overall findings provide useful information to improve the biomass productivity of microalgae for their application to the food and feed sectors; this aspect should be emphasized in the Discussion section where the changing of nutrient composition due to the different light quality could be evaluated as the basis for diverse applications of cultivated microalgae in different fields.
Although it is known that light intensity can modulate the synthesis of pigments in microalgae, and albeit their economic importance, the authors did not analysed these metabolites; this aspect should give important data. A brief mention is in the first lines of the abstract, where I suggest substituting “the accumulation of secondary metabolites” (lines 10-11) with “their nutrient composition”.
In the Materials and Methods section, I suggest to partially remodulate as suggested below and to describe the centrifugation speed by xg that is not varying by different centrifuge rotors. The Conclusions should highlight the importance of the obtained findings for microalgae production and their potential applications in relevant industrial fields.
The ms still needs some work to improve the text and figures.
Minor points
Figures need some work: a double legend is not useful and subtract some space that can be used for improving the graphs’ readability. If possible, I would suggest to uniform the style of the figures 2 and 3.
Line 65: “bait” is probably not appropriate?
Line 82: delate “2.2. Experimental method” and proceed with progressive numeration of the subsequent paragraphs.
Line 94: please substitute “8000 rpm·min-1“ with xg, here and throughout the ms.
Line 141: “Wang et al.”, reference is not according to guideline.
Line 164: “Table 1. showed the fatty acids composition change compared to while light condition”, please delete the mark after table 1 and what do you mean with “compared to white light”? statistical analysis is among all the different light qualities.
Line 199: [23] should move after Sirisuk et al.
Line 225: please substitute “liquidity of cell membranes” with “fluidity of cell membranes”.
Line 237: “(Figure 2)” should probably be (Fig. 2) for uniformity of the text. Please check Figure 3 (lines 188-189), too.
Line 273: add “in” aquaculture.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The entitled ms: “The effects of LED light quality on the mail nutritional compositions of Isochrysis zhanjiangensis” is a research article and is of interest for the cultivation of the species and its use in aquaculture and aquaculture technology. There is need for English editing
Lines 68-73: you can briefly explain why you have chosen these lights, and it depends on the development-absorption of the species.
Line 93: Could you explain briefly why the duration of the culture was 12 days?
At the end of the materials and methods, you failed to mention the statistical analysis you have performed with the data analyses since, in the results; it refers to statistical differences (Line 144). Please rewrite
Line 146-192: Τhe results could be presented in a better way. it is proposed to add a table showing the protein and carbohydrate data to understand and illustrate the results more clearly in combination with the graphs
Also, the graphs that are in the text need better resolution and magnification because make it nearly impossible to grab the point
In conclusion, how does this translate into practice for aquaculture and aquaculture technology? Can you explain bliefly
you should review and verify the references throughout the document according to the guidelines suggested by the journal for example: line 199 Sirusuk et al. found that [23]..or line 250 etc..
is missing the reference [44]
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear authors,
Your revision significantly improved the manuscript. I only have two minor comments.
1. RPM and g are not the same thing, g also depends on the radius of the centrifuge rotor. Please check this calculator from Sigma Aldrich. https://www.sigmaaldrich.com/US/en/support/calculators-and-apps/g-force-calculator
2. Table 2 and Figure 3 present the same data, so they are redundant. Please eliminate one of them.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Dear Authors
According to the new revised manuscript all points were covered and therefore as formulated, this manuscript has been improved therefore I agree to publish it
Author Response
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Author Response File: Author Response.pdf
