Dunaliella viridis TAV01: A Halotolerant, Protein-Rich Microalga from the Algarve Coast

Round 1

Reviewer 1 Report

The paper is well written and organized. It is a classic paper of characterization of a mciroalgae, being the novelty the mciroalgae itself.

Author Response

We would like to thank the reviewer for the kind words.

Reviewer 2 Report

1. Why did the authors choose a salinity 5 times higher than the original one for the culture after isolating Dunaliella sp. TAV01 strain? The authors also mentioned that there might be a difference between the measured values of microalgae grown in 3M NACI and those of 2M, but why no comparative test was set up to detect it.

2. The authors mention that the culture conditions affect the material content of microalgae, but the other microalgae compared with TAV01 are not in the same culture conditions, so is this discussion convincing enough?

3. Suggest to increase the font size of Figure 2.

4. Figure 3 suggest to put the secondary structure comparison of two strains.

5. The article has too many references.

6. The article lacks the description of Figure 1C.

Author Response

1. Why did the authors choose a salinity 5 times higher than the original one for the culture after isolating Dunaliella sp. TAV01 strain? The authors also mentioned that there might be a difference between the measured values of microalgae grown in 3M NACI and those of 2M, but why no comparative test was set up to detect it.

The Dunaliella viridis TAV01 strain was isolated from a saline pond, in which the salinity was approximately the one used to cultivate the strain in the laboratory. The pond at the time presented an orange colour, which we aimed to replicate at lab scale.

2. The authors mention that the culture conditions affect the material content of microalgae, but the other microalgae compared with TAV01 are not in the same culture conditions, so is this discussion convincing enough?

The reply is linked to the reply for the previous question, and most probably the authors cited used conditions similar to the ones found in the habitat they were isolated from. Thus, we think that the conditions must be adapted for each strain, depending on their provenance. Using different conditions for growing microalgae is not only a necessity but it is adequate for what each team of authors is trying to achieve. Therefore, it is unavoidable to compare results obtained under different growing conditions, as the replication of the exact conditions is quite hard. Sometimes, just a change in the water source is already enough to get different results.

3. Suggest to increase the font size of Figure 2.

The font size was increased as suggested.

4. Figure 3 suggest to put the secondary structure comparison of two strains.

As suggested, we’ve complemented the figure with the ITS2 secondary structures of Dunaliella salina and a different strain of Dunaliella viridis highlighting respectively the differences and similarities between different Dunaliella strains and the Dunaliella viridis TAV01 strain.

5. The article has too many references.

We understand the concern with the number of references; however, upon revision of all references, the authors concluded they are important for the entire work to be understood and properly discussed.

6. The article lacks the description of Figure 1C.

The description of Figure 1C was added to the legend.

Reviewer 3 Report

The manuscript is very well structured and presented by the authors. 

The research is of scientific importance and has been performed with applications of numerous modern techniques.

(I would only recommend to add into Materials and Methods part data on statistical processing of received experimental data)

Author Response

We thank the reviewer for the kind words. A section on Statistical Analysis was added to the Materials and Methods.

Reviewer 4 Report

Although the paper can be accepted on the experimental point of view. I suggest several modifications. The substantial modifications concern the emphasis about the possible practical utilization of the strain, for instance the utilization as food supplement, considering this is one of the main commercial value of microalgae. The interest for this type of alga for the content of glycerol is an example. I suggest to add some information about the classification of genus in line 59, like the family Dunaliellaceae and the order Volvocales.  Please, check typing and other minor errors in lines 84 (add a comma after compounds), 88, 147 and 151, 10 (change in Spirulina and add sp.), 271, 304-308, 336, 347, 349-351, 394, 396, 381 and other probably present.

Author Response

Although the paper can be accepted on the experimental point of view. I suggest several modifications. The substantial modifications concern the emphasis about the possible practical utilization of the strain, for instance the utilization as food supplement, considering this is one of the main commercial value of microalgae. The interest for this type of alga for the content of glycerol is an example.

As our aim is to show the possibility of using Dunaliella viridis TAV01 as a food supplement or even food in the future, we’ve modified the conclusions to highlight this as clearly as possible. As the glycerol content was not analysed, we understand that adding information about the compound may only distract from the actual aim of the work. However, we’ve added information regarding the market size of microalgae in general (Introduction, L54-55) and of lutein (the major pigment of this strain) to better illustrate the importance of microalgae in the food market (Results and Discussion, L453-456).

I suggest to add some information about the classification of genus in line 59, like the family Dunaliellaceae and the order Volvocales.  

Information about the algae classification was added as suggested (L60-61).

Please, check typing and other minor errors in lines 84 (add a comma after compounds), 88, 147 and 151, 10 (change in Spirulina and add sp.), 271, 304-308, 336, 347, 349-351, 394, 396, 381 and other probably present.

All typing errors highlighted were corrected and an extensive search for more typing slips was conducted. Concerning Spirulina, we removed all references in italic, as that is the name of the product and not the taxonomic name of the algal species, in this case Arthrospira platensis. We decided to keep the non-italicized name “Spirulina”, as that is the most common name found in food products.

Reviewer 5 Report

Title: accepted

Introduction: well elaborate. if possible provide some value of microalgae in world trade

Materials and methods: accepted

If possible please separate result and discussion

1. What is the main question addressed by the research?

The tolerance of novelty microalgae to harsh environment

2. Do you consider the topic original or relevant in the field? Does it

address a specific gap in the field?

Yes

3. What does it add to the subject area compared with other published

material?

THe potential of microalgae for human consumption

4. What specific improvements should the authors consider regarding the

methodology? What further controls should be considered?

NO

5. Are the conclusions consistent with the evidence and arguments presented

and do they address the main question posed?

Yes

6. Are the references appropriate?

Yes

7. Please include any additional comments on the tables and figures.

NO

Author Response

Introduction: well elaborate. if possible provide some value of microalgae in world trade

Information regarding the market size of microalgae in general (Introduction, L54-55) and of lutein (the major pigment of this strain) was added to the manuscript to better illustrate the importance of microalgae in the food market (Results and Discussion, L453-456).

If possible please separate result and discussion

The authors consider that separating the results from the discussion, in this case, would difficult the understanding of the complete scope of the work. If possible, we would like to keep the manuscript as is.

Round 2

Reviewer 2 Report

Accept revision